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www.sciencedirect.com
c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 0
Available online at
ScienceDirect
Journal homepage: www.elsevier.com/locate/cortex
Special issue: Research report
The blind mind: No sensory visual imagery in
aphantasia
Rebecca Keogh* and Joel Pearson
School of Psychology, University of New South Wales, Sydney,
Australia
a r t i c l e i n f o
Article history:
Received 30 January 2017
Reviewed 3 May 2017
Revised 27 June 2017
Accepted 15 October 2017
Published online 28 October 2017
Keywords:

4. Aphantasia
Visual imagery
Individual differences
Cognition
Mental imagery
* Corresponding author. School of Psycholog
E-mail address: [email protected]
https://doi.org/10.1016/j.cortex.2017.10.012
0010-9452/© 2017 Elsevier Ltd. All rights rese
a b s t r a c t
For most people the use of visual imagery is pervasive in daily
life, but for a small group of
people the experience of visual imagery is entirely unknown.
Research based on subjective
phenomenology indicates that otherwise healthy people can
completely lack the experi-
ence of visual imagery, a condition now referred to as
aphantasia. As congenital aphan-
tasia has thus far been based on subjective reports, it remains
unclear whether individuals
are really unable to imagine visually, or if they have very poor
metacognition e they have
images in their mind, but are blind to them. Here we measured
sensory imagery in sub-

5. jectively self-diagnosed aphantasics, using the binocular rivalry
paradigm, as well as
measuring their self-rated object and spatial imagery with
multiple questionnaires (VVIQ,
SUIS and OSIQ). Unlike, the general population, experimentally
naive aphantasics showed
almost no imagery-based rivalry priming. Aphantasic
participants' self-rated visual object
imagery was significantly below average, however their spatial
imagery scores were above
average. These data suggest that aphantasia is a condition
involving a lack of sensory and
phenomenal imagery, and not a lack of metacognition. The
possible underlying neuro-
logical cause of aphantasia is discussed as well as future
research directions.
© 2017 Elsevier Ltd. All rights reserved.
‘What does a person mean when he closes his eyes or ears
(figuratively speaking) and says, “I see the house where I
was born, the trundle bed in my mother's room where I
used to sleep e I can even see my mother as she comes to
tuck me in and I can even hear her voice as she softly says
goodnight”? Touching, of course, but sheer bunk. We are

6. merely dramatizing. The behaviourist finds no proof in
imagery in all this. We have put these things in words long,
long ago and we constantly rehearse those scenes verbally
whenever the occasion arises’
John B Watson
y, University of New Sou
(R. Keogh).
rved.
The study of visual imagery has been a controversial topic
for many years, as the above quote from the behaviourist John
Watson demonstrates. This quote exemplifies the long
running imagery debate of the 1970s and 80's, which centred on
the question of whether imagery can be depictive in the format
of its representation (Kosslyn, 2005), or only symbolic or
propositional in nature (Pylyshyn, 2003). However, in the last
few decades psychologists and neuroscientists have made
great strides in showing that visual imagery can be measured
objectively and reliably, and indeed can be depictive/pictorial
in nature, see Pearson and Kosslyn (2015) for a detailed
th Wales, Sydney, Australia.
mailto:[email protected]

7. http://crossmark.crossref.org/dialog/?doi=10.1016/j.cortex.2017
.10.012&domain=pdf
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discussion of the evidence. Research has shown that visual
imagery, like weak perception, impacts subsequent perception
in a myriad of ways (Ishai & Sagi, 1995; Pearson, Clifford, &
Tong, 2008; Winawer, Huk, & Boroditsky, 2010; Zamuner,
Oxner, & Hayward, 2017). For example, the effect of imagery
on subsequent rivalry is specific in orientation and location
space, showing strong evidence for a depictive representation
(Pearson et al., 2008). Imagery has also been shown to activate
early visual cortex and the content of imagery can be decoded
in these areas using an encoding model based on low-level
depictive visual features, such as spatial orientation and
contrast (Naselaris, Olman, Stansbury, Ugurbil, & Gallant,

8. 2015), and recently using features based on a multi-level con-
volutional neural network (Horikawa & Kamitani, 2017).
Additionally, visual imagery has been shown to be closely
related to many cognitive functions such as visual memory
(Albers, Kok, Toni, Dijkerman, & de Lange, 2013; Keogh &
Pearson, 2011, 2014), spatial navigation (Ghaem et al., 1997),
language comprehension (Bergen, Lindsay, Matlock, &
Narayanan, 2007; Zwaan, Stanfield, & Yaxley, 2002), making
moral decisions and making a decision to help others (Amit &
Greene, 2012; Gaesser & Schacter, 2014). Visual imagery also
appears to be elevated (stronger or more vivid) in some psy-
chological and neurological disorders (Matthews, Collins,
Thakkar, & Park, 2014; Sack, van de Ven, Etschenberg,
Schatz, & Linden, 2005; Shine et al., 2015). Visual imagery
has even been employed to assist in cognitive behavioural
therapies such as imaginal exposure and imaginal rescripting
(Arntz, Tiesema, & Kindt, 2007; Holmes, Arntz, & Smucker,
2007; Pearson, Naselaris, Holmes, & Kosslyn, 2015) and the

9. use of visual imagery during cognitive behavioural therapy
has been shown to be more effective than just verbal pro-
cessing (Pearson et al., 2015).
With strong evidence that visual imagery can be a depictive
cognitive mechanism, the question arises, were Watson,
Pylyshyn and their ilk wrong? Or is it possible that they had a
distinctly different experience of visual imagery that was not
depictive, but more propositional or phonological in nature?
Interestingly, a study investigated exactly this idea and found
that those researchers who were more likely to have been on
the ‘imagery is depictive’ side of the debate tended to report
more vivid imagery, while those who reported weaker imag-
ery were more likely to be on the imagery is propositional side
of the debate (Reisberg, Pearson, & Kosslyn, 2003). One of the
hallmarks of visual imagery is the large range of subjective
reports in the vividness of an individual's imagery. For
example, when people are asked to imagine the face of a close
friend or relative some people report imagery so strong it is

10. almost akin to seeing that person, whereas others report their
imagery as so poor that, although they know they are thinking
about the person, there is no visual image at all. Sir Francis
Galton gave one of the earliest accounts of these subjective
differences in visual imagery in 1883. Galton devised a series
of questionnaires asking participants to imagine a specific
object then describe the ‘illumination’, ‘definition’ and ‘col-
ouring’ of the image. He found, to his surprise, that many of
his fellow scientists professed to experience no visual images
in their mind at all: ‘To my astonishment, I found that the
great majority of the men of science to whom I first applied
protested that mental imagery was unknown to them, and
they, looked on me as fanciful and fantastic in supposing that
the words “mental imagery” really expressed what I believed
everybody supposed them to mean. They had no more notion
of its true nature than a colour-blind man, who has not dis-
cerned his defect, has of the nature of colour. They had a
mental deficiency of which they were unaware, and naturally
enough supposed that those who affirmed they possessed it,

11. were romancing.” In recent years very little attention has been
given to the ‘poor’ or non-existent side of the visual imagery
spectrum, outside of participants with neurological damage.
Much research during the imagery debate of the 70's and 80's
revolved around brain damaged participants who had lost
their ability to imagine, but retained their vision, or vice versa
(Farah, 1988). Recently the idea that some people are wholly
unable to create visual images in mind, without any sort of
neurological damage, psychiatric or psychological disorders,
has seen a resurgence. A recent paper by Zeman, Dewar, and
Della Sala (2015) coined a term for this phenomenon
‘congenital aphantasia’. This study found that these aphan-
tasics all scored very low on the vividness of visual imagery
questionnaire (VVIQ). The VVIQ is a commonly used ques-
tionnaire to measure the subjective vividness of an in-
dividual's visual imagery, by asking them to imagine a friend
or relative, as well as scenes and rate the vividness of these
images on a Likert scale. However, a case study reported a 65-
year-old male who became aphantasic after surgery (without

12. any obvious neurological damage) and was still able to
perform well on other measures of visual imagery, such as
answering questions about the shape of animal's tails. The
patient was also able to perform two types of mental rotation
tasks (manikin and ShepardeMetzler tasks), which are
commonly used test of imagery ability (A. Z. Zeman et al.,
2010). Interestingly, his reaction times however, did not
correspond to the rotation distance, which is the common
finding in the literature. These reports suggest the possibility
that aphantasic individuals do actually create images in mind
that they are able to use to solve these tasks, however they are
unaware of these images; that is they lack metacognition, or
an inability to introspect.
Although the visual imagery tasks used in the Zeman et al.
(2010) study are used extensively throughout the imagery
literature, and in clinical settings to measure visual imagery,
the validity of these tasks are somewhat unclear. For example,
in the animal tails test it may be that subjects can use prop-

13. ositional semantic information about the images they are
asked to imagine, instead of actually creating a visual image in
mind. Additionally, the mental rotation task used (manikin
and ShepardeMetzler tests) could be performed using spatial,
or kinaesthetic imagery, rather than ‘low-level’ visual object
imagery. A relatively new experimental imagery task, which
exploits a visual illusion known as binocular rivalry, allows us
to eliminate many of the issues related to these visual imagery
measures (Pearson, 2014). Binocular rivalry is an illusion, or
process, where one image is presented to the left eye and a
different image to the right, which results in one of the images
becoming dominant while the other is suppressed outside of
awareness (see Fig. 1A for illustration). Previous work has
demonstrated that presenting a very weak visual image of one
of the rivalry patterns prior to the presentation of the binoc-
ular rivalry display, results in a higher probability of that
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impacts of weak visual imagery
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Parts of brain activated in visual imagery
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cognitive functions related to visual imagery:
- Visual memory
-Spatial navigation
-language comprehension
-moral decision making
-Some psychological and neurological disorders
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Study addressing whether visual imagery is depictive or more
propositional and phonological in nature
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VVIQ
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argument against Zeman's methods
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Binocular rivalry definition and method
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image being seen in the subsequent binocular rivalry pre-
sentation (Brascamp, Knapen, Kanai, van Ee, & van den Berg,
2007; Pearson et al., 2008). Interestingly, when someone
imagines an image instead of being presented with a weak
one, a very similar pattern of results emerges. In other words,
imagery can prime subsequent rivalry dominance much like
weak visual perception (Pearson, 2014; Pearson et al., 2008).
Hence, this imagery paradigm has been referred to as a
measure of the sensory strength of imagery, as it bypasses the
need for any self-reports and directly measures sensory
priming from the mental image.
If an individual is presented with a uniform and passive lu-
minous background while they generate an image, the facilita-
tive effect of their mental image is reduced (Chang, Lewis, &

16. Pearson, 2013; Keogh & Pearson, 2011, 2014, 2017; Sherwood
&
Pearson, 2010). Previous work has shown that these disruptive
effects are limited to visual tasks that require the use of depic-
tive image generation (Keogh & Pearson, 2011, 2014)
suggesting
that the early visual areas of the brain are likely involved in the
construction and maintenance of these images. Further, this
priming effect is local in both retinotopic spatial-locations and
orientation feature space (Bergmann, Genç, Kohler, Singer, &
Pearson, 2015; Pearson et al., 2008), further suggesting the
priming is contingent on early visual processes.
This measure of visual imagery also correlates with sub-
jective ratings of visual imagery, both trial-by-trial and ques-
tionnaire ratings, suggesting that participants have insight
into the strength of their own visual imagery (Bergmann et al.,
2015; Rademaker & Pearson, 2012). Here we ran a group of
selfedescribed congenital aphantasics on the binocular ri-
valry visual imagery paradigm to measure the strength of

17. their sensory imagery. If congenital aphantasia is a complete
lack of visual imagery, we should expect no facilitative prim-
ing effects of visual imagery on subsequent rivalry. However,
if congenital aphantasia is instead a lack of metacognition, or
failed introspection, then we may expect to observe some
priming, despite the subjective reports of no imagery. We
further, tested the aphantasics on a range of standard
Fig. 1 e Binocular rivalry and experimental timeline. A.
Illustration o
images are presented, one to each eye, instead of seeing a mix
of
Fluctuations only occur for prolonged viewing, not for our brief
riv
Participants were cued to imagine one of two images (r ¼ red-
hor
Participants imagined this image for 6 sec, then after 6 sec they
ra
After this they were presented with a very brief binocular
rivalry d
questionnaires to probe the vividness and spatial qualities of
their imagery.
1. Methods and materials
1.1. Participants

18. Fifteen (aged 21e68, 7 female) self-described aphantasic par-
ticipants completed all experiments and questionnaires. The
Aphantasics were recruited through a Facebook page, had
emailed the lab regarding their aphantasia or were referred to
us by Adam Zeman. All aphantasic participants indicated that
they could not remember a time they could imagine and there
was no injury that had led them to becoming aphantasic. We
did not however do a full neurological exam of the partici-
pants. The control, or ‘general population’ group uses data
that was collected over numerous experiments, some of
which were published in a number of different journal articles
(see Keogh & Pearson (2011, 2014); Shine et al. (2015)): while
some are as yet unpublished, all using the same binocular
rivalry visual imagery task, with the exact same stimuli and
instructions, however not all of the studies included vividness
ratings; the sample contains 209 different individuals. The age
range of these 209 participants is from young adult (18 years þ)
to elderly (80's). All participants had normal or corrected to
normal vision (i.e., wore glasses or contacts).

19. Fifteen control participants also completed the OSIQ (age
range 18e35, 10 female).
1.2. Stimuli
All participants (in the aphantasic and general population)
were tested in blackened rooms with the lights off, and their
viewing distance from the monitor was 57 cm and was fixed
with the use of a chin rest. The data for the general population
were collected over several years and used several different
computer monitors and testing rooms, as such the stimuli
f an extended binocular rivalry presentation. Two separate
the two, perception alternates between the two images.
alry presentation. B. Binocular rivalry experimental timeline.
izontal Gabor patch and g ¼ green-vertical Gabor patch).
ted how vivid the image they created was on a scale of 1e4.
isplay (750 msec) and had to report which colour they saw.
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Binocular Rivalry as a better measuring system of sensory
strength of imagery

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parameters will all be slightly different, due to monitor and
graphics card differences. However, all the experiments were
performed by the same experimenter (RK), who ran all par-
ticipants in the aphantasia and general population studies.
The following specific stimuli parameters described, are for

21. the aphantasic participants of this study.
In the imagery task the binocular rivalry stimuli consisted
of red horizontal (CIE x ¼ .57, y ¼ .36) and green vertical (CIE
x ¼ .28, y ¼ .63) Gabor patterns, 1 cycle/�, Gaussian s ¼ 1.5�.
Gabor patterns are sinusoidal gratings with a Gaussian enve-
lope applied. The patterns were presented in an annulus
around the fixation point and both Gabor patterns had a mean
luminance of 4.41 cdm2. The background was black
throughout the entire task during the no luminance condition.
For the imagery luminance condition the background ramped
up to yellow (a mix of the green and red colours used for the
rivalry patterns, with luminance at 4.41 cdm2), during the six-
second imagery period. During this period the background
luminance was smoothly ramped up and down to avoid visual
transients, which may result in attention being directed away
from the task.
Mock rivalry displays were included on 12.5% of trials to
assess any effects of decisional bias in the imagery task. One
half of the mock rivalry stimuli was a red Gabor patch, with

22. the other half being a green Gabor patch (a spatial mix) and
they shared the same parameters as the green and red Gabor
patches mentioned in the previous paragraph. The mock ri-
valry stimuli were spatially split with blurred edges and the
exact division-path differed on each catch trial (random walk
zigezag edge) to resemble actual piecemeal rivalry. The
aphantasic participants mock priming was not significantly
different to 50% (t(14) ¼ 1.08, p ¼ .30), indicating a lack of
decisional priming.
1.3. Experimental procedure
All aphantasic participants came to the University of New
South Wales to participate in approximately 3 h of testing.
They were reimbursed $15 AUD per hour for their participa-
tion in the study. At the beginning of the experimental session
they were briefed verbally about the study (they were told they
were going to fill-in some questionnaires, see some visual il-
lusions, do some memory tests and imagine some pictures)
and written informed consent was obtained. The participants

23. then completed the following questionnaires and binocular
rivalry task (lasting for about 1e1.5 h) as well as completing
some other memory and imagery tasks for a different study,
not reported on here.
1.4. Questionnaires
All participants completed the vividness of visual imagery
questionnaire (VVIQ2) (Marks, 1973), spontaneous use of im-
agery scale (SUIS) (Reisberg, Culver, Heuer, & Fischman,
1986),
and the object and spatial imagery questionnaire (OSIQ)
(Blajenkova, Kozhevnikov, & Motes, 2006). The VVIQ asks
participants to imagine several scenes and then rate how vivid
their imagery is for each item on a scale of 1e5; with 1 ¼ ‘No
image at all, you only “know” that you are thinking of the
object’ and 5 ¼ ‘Perfectly clear and vivid as normal vision’.
Both the SUIS and the OSIQ give participants statements and
they have to rate how much they agree with the statement
from 1 to 5, with 1 ¼ ‘totally disagree’ and 5 ¼ ‘totally agree’.
An example question from the SUIS is: ‘When I hear a radio
announcer or DJ I've never actually seen, I usually find myself
picturing what they might look like’.

24. 1.5. Binocular rivalry task
Before completing the binocular rivalry imagery task each
participant's eye dominance was assessed (for a more in depth
explanation see Pearson et al. (2008)) to ensure rivalry domi-
nance was not being driven by pre-existing eye dominance, as
this would prevent imagery affecting rivalry dominance.
Following the eye dominance task participants completed
either 2 or 3 blocks of 40 trials depending on time constraints
and number of mixed percepts. Mixed percept trials were not
analysed here, so for this reason we attempted to have at least
60 analysable trials per participant, however due to time
constraints and mixes, 4 participants only completed 32, 34,
35, and 45 trials. There was however no correlation between
the number of trials completed and rivalry priming (rs ¼ .04,
p ¼ .90, Spearman's correction for non-normality), hence these
participants' data are included in the analysis. Participants
also completed 2 or 3 blocks of 40 trials of the binocular rivalry
task with a luminous background during the imagery period.
Binocular rivalry imagery paradigm: Fig. 1B shows the time-
line of the binocular rivalry imagery experiment. At the

25. beginning of each trial participants were presented with
either an ‘R’ or a ‘G’ which cued them to imagine either a red-
horizontal Gabor patch (‘R’) or a green-vertical Gabor patch
(‘G’). Following this, participants were presented with an im-
agery period of 6 sec. In the no luminance condition the
background remained black during this imagery period, in the
luminance condition the background ramped up and down to
yellow over the first and last second of the 6 sec imagery
period to avoid visual transients. After this 6 sec period par-
ticipants were asked to rate how ‘vivid’ the image they
imagined was on a scale of 1e4 (using their left hand on the
numbers on the top of the keyboard) with ‘1’ ¼ ‘No image at
all, you only “know” that you are thinking of the object’ and
‘4’ ¼ ‘Perfectly vivid’. After this they were presented with a
binocular rivalry display comprising the red-horizontal and
green-vertical Gabor patches and asked to indicate which
image they saw most, of using their right hand on the key pad:
‘1’ ¼ green-vertical, ‘2’ ¼ perfectly mixed, ‘3’ ¼ red-
horizontal.
2. Results

26. Table 1 and Fig. 2AeC show participants' scores on the visual
imagery questionnaires. The data supports Zeman et al. (2015)
findings that aphantasic participants rate their imagery as
very poor or non-existent on the VVIQ. These data also show
that participants also rate their spontaneous use of visual
imagery as very low on both the SUIS and Object component
of the OSIQ. Interestingly, the aphantasic participants' spatial
component of the OSIQ was almost double that of their object
score. To further assess this finding 15 non-age matched
participants also completed the OSIQ. There was a significant
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Table 1 e Average scores on visual imagery questionnaires for
the aphantasic participants.
Object OSIQ/75 Spatial OSIQ/75 VVIQ/80 SUIS/60
Total score mean 21.53 41.80 19.00 17.20
Standard deviation 3.46 10.33 6.78 1.65
Fig. 2 e Frequency Histograms for aphantasic participants

27. scores on the VVIQ (Bins ¼ 2) (A), SUIS (Bins ¼ 2) (B) and
Object
components of the OSIQ (Bins ¼ 2) (C). D. Object and spatial
scores on the OSIQ for aphantasic (white bars) and control
participants (grey bars). E. Frequency histogram for imagery
priming scores for aphantasic participants (yellow bars and
orange line) and general population (grey bars and black dashed
line), (Bins ¼ 5). The green dashed line shows chance
performance (50% priming). F. Average priming scores for
aphantasic participants in the no background luminance
condition (dark grey bar), aphantasic participants in the
background luminance condition (white bar) and general
population with no background luminance (light grey bar). G.
Mean ‘online’ trial-by-trial vividness ratings for aphantasic
participants in the no background luminance (grey bars) and
luminous background condition (white bar). H. Frequency
histogram of Bootstrapping from the general population data
(Bins ¼ 1). 15 subjects were randomly chosen, averaged, then
returned to the main pool of subjects. Data shows the
distribution of the mean of N ¼ 15 for 1000 iterations. The
aphantasic
mean is shown on the far left (orange dotted line), with a P ¼
.001 chance of pulling such a mean from the general
population. All error bars show ±SD's
c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 0 57
interaction between the spatial and object components of the
OSIQ and the participant group (aphantasic/control), Mixed
repeated measures ANOVA: F(1, 28) ¼ 45.25, p < .001 (see

28. Fig. 2D). Post hoc analysis of the simple effects demonstrated
that as expected the aphantasic participants rated their use of
spontaneous object imagery as significantly lower than the
controls (p < .001). The aphantasics self-rated spontaneous
use of spatial imagery was not significantly higher than the
controls (p ¼ .15), mean scores: Aphantasic ¼ 41.80 and
control ¼ 36.53.
Next the binocular rivalry imagery priming scores were
examined. As can be seen in Fig. 2E and F, aphantasics had
significantly lower priming on average than our general
sample of participants (ManneWhitney U ¼ 914, p < .01, 2-
tailed). In fact, the aphantasic group's priming scores were not
significantly different from chance (50%) (Fig. 1E grey filled
bar,
one sample t-test: t(14) ¼ .68, p ¼ .51), unlike the general
population whose mean is significantly different to chance
(one sample t-test: t(208) ¼ 10.96, p < .001). There were also
no
correlations between visual imagery priming for the aphan-
tasic participants and any of the questionnaire measures,
likely due to a restriction of range (all p's >. 37). Additionally,
when aphantasic participants completed the task with a lu-
minous background during the imagery period, their priming

29. was no different to priming in the no luminance condition
(paired sample t-test: t(14) ¼ 1.10 p ¼ .29) and was again not
significantly different from chance (one sample t-test:
t(14) ¼ 1.75, p ¼ .10). These results suggest that the aphantasic
participant's imagery has little effect on subsequent binocular
rivalry. Aphantasic participants' mean ‘online’ trial-by-trial
vividness ratings were also very low, with the average rat-
ings not significantly different from the lowest rating of 1 (one
sample t-tests: no luminance condition: t(14) ¼ 1.18, p ¼ .36,
luminance condition: 1.37, p ¼ .19, see Fig. 2G). The vividness
ratings were not different between the no luminance and
luminance conditions (paired sample t-test: t(14) ¼ 1.10,
p ¼ .29).
One possible explanation for the observed differences be-
tween aphantasics and the general population may be that the
eye dominance test simply did not adequately work for the
aphantasic group, thus preventing any imagery priming. If a
participant naturally has one eye that dominates over the
other, this will result in them only seeing the one image that is
presented to that dominant eye e which will result in chance
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30. c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 058
levels of priming. At the beginning of the imagery experiment
all participants complete an eye dominance task to assess
which eye is dominant. The contrast of the red and green
Gabor patches are then adjusted in accordance with the par-
ticipant's eye dominance, e.g., if the participant sees more
green/has a stronger left eye, the contrast of the green Gabor
patch will be decreased, while the red Gabor patch is
increased. This results in each participant having different eye
dominance values. To assess whether eye dominance differ-
ences might be driving our effect, or lack of effect, we
compared eye dominance values (red and green contrasts)
used for the aphantasic participants with 15 other partici-
pants randomly drawn from the general population pool. We
found that there was no significant difference in the eye
dominance values for the aphantasic and control participants,
with no interaction between the …
Assignment 4: Adding Your Voice to the Conversation

31. Overview: Now that you have thoroughly researched an issue
looking at multiple perspectives and stakeholders, you are ready
to write an academic argument for one of the specific
stakeholders. The argument you write for this assignment will
be academic in that it is a research-based, source-based
argument. You may use the sources you already found, but you
should continue to find new sources to support your argument
and represent the conversation on the issue. Furthermore, your
argument should add something unique or new to the
conversation and not just repeat someone else's argument.
Purpose: The purpose for this assignment will depend on your
intended audience. It will most likely fall into one of the
following general categories (remember—how far do you expect
them to cross the street for you?):
To convince undecided readers to accept your thesis
To make opposing readers less resistant to your thesis
To convince readers who agree with you to take action
To promote awareness of an issue within an audience you
believe needs to consider it more
Audience: You’ll need to consider these readers' expectations as
you write your argument—from tone and language, to reasoning
and supporting evidence, to the format/genre and execution of
your writing.
The audience for this argument has two levels to it. First, your
stakeholder, which will vary from writer to writer. Second,
your academic audience. This second especially will expect a
clear, logical argument that remains focused on proving a
thesis. These readers, being in some way connected to the
academic community, expect that an argument is well-
researched and that the argument is supported with reasons and
evidence. They want to see that you are familiar with the
conversation on the issue and how your argument contributes to
that conversation. In addition, such readers require full citations

32. for all sources you use. Your audience also expects your writing
to be free from errors.
Issue & Sources: Write your argument about the issue you just
investigated. You may use the sources from your annotated
bibliography, but you should continue to find sources to fit the
rhetorical situation (which will change as you make rhetorical
choices about purpose and audience specific to this assignment).
You should include a minimum of five relevant/reliable/recent
sources, and you might consider making at least one of these an
instance of field research: an interview that you conduct with a
relevant and authoritative expert here on campus, in Fort
Collins, or in a surrounding community.
Author: Present yourself as a knowledgeable, fair-minded,
credible and, as appropriate, empathetic person. You do not
need to be an expert on your issue to write an argument, but you
do need to have confidence in what you do know and believe
about it. Show that you approach the issue with enthusiasm,
intellectual curiosity, and an open mind.
Details:
Format: This class is meant to help prepare you for college
writing, but also writing you might do outside of and beyond
college. So even though you may be writing in a genre that
does not use MLA conventions, your paper should be formatted
according to MLA conventions. This includes MLA-style
heading and page numbers, parenthetical citations within your
paper for all sources used (quotes, paraphrases, facts, ideas,
etc.) and a Works Cited page at the end of your paper (see
Pocket Keys for Writers).
Length: minimum 5 full pages text, double spaced, standard
margins & font (not including Works Cited or significant
header), maximum 7 pages. I care about quality, not quantity

33. for this assignment, and shorting the paper is not a good idea.
Worth: 25% of your course grade
A4 Rubric – Ideal goals
LOGOS
The argument is clear
The thesis is specific and debatable; it can be argued in the
scope of 5-7 pages
The reasoning behind the argument is thoughtful and logical,
and avoids hasty generalizations, false dichotomies, or other
common “logical fallacies”
The writer provides significant evidence from research to
introduce, illustrate, and/or support the argument and reasoning
The evidence is relevant and the interpretation of the evidence
logically supports the case being made
ETHOS
The writer/arguer comes across as knowledgeable, reasoned,
and reliable, and generally uses correct grammar, spelling, and
MLA conventions
The writer has used reliable sources
The writer has successfully conveyed credibility of their
sources to the reader
The writer has thoughtfully addressed/refuted a credible
opposing argument, which is also represented by a credible
source
AUDIENCE
The argument and paper are geared toward a target audience,

34. probably a major or minor stakeholder in the issue
The writer, whether or not they explicitly state the values, has
clearly taken audience values, needs, experiences and concerns
into consideration
The writing attempts to address these values, etc., in
language/vocabulary, reasoning, and evidence
The piece generally conforms to necessary genre conventions
(of its chosen genre: open letter, magazine article for Time or
other publication, etc.)
www.sciencedirect.com
c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 0
Available online at
ScienceDirect
Journal homepage: www.elsevier.com/locate/cortex
Special issue: Research report
The blind mind: No sensory visual imagery in
aphantasia
Rebecca Keogh* and Joel Pearson
School of Psychology, University of New South Wales, Sydney,
Australia
a r t i c l e i n f o
Article history:
Received 30 January 2017
Reviewed 3 May 2017
Revised 27 June 2017

35. Accepted 15 October 2017
Published online 28 October 2017
Keywords:
Aphantasia
Visual imagery
Individual differences
Cognition
Mental imagery
* Corresponding author. School of Psycholog
E-mail address: [email protected]
https://doi.org/10.1016/j.cortex.2017.10.012
0010-9452/© 2017 Elsevier Ltd. All rights rese
a b s t r a c t
For most people the use of visual imagery is pervasive in daily
life, but for a small group of
people the experience of visual imagery is entirely unknown.
Research based on subjective
phenomenology indicates that otherwise healthy people can
completely lack the experi-
ence of visual imagery, a condition now referred to as
aphantasia. As congenital aphan-
tasia has thus far been based on subjective reports, it remains
unclear whether individuals

36. are really unable to imagine visually, or if they have very poor
metacognition e they have
images in their mind, but are blind to them. Here we measured
sensory imagery in sub-
jectively self-diagnosed aphantasics, using the binocular rivalry
paradigm, as well as
measuring their self-rated object and spatial imagery with
multiple questionnaires (VVIQ,
SUIS and OSIQ). Unlike, the general population, experimentally
naive aphantasics showed
almost no imagery-based rivalry priming. Aphantasic
participants' self-rated visual object
imagery was significantly below average, however their spatial
imagery scores were above
average. These data suggest that aphantasia is a condition
involving a lack of sensory and
phenomenal imagery, and not a lack of metacognition. The
possible underlying neuro-
logical cause of aphantasia is discussed as well as future
research directions.
© 2017 Elsevier Ltd. All rights reserved.
‘What does a person mean when he closes his eyes or ears
(figuratively speaking) and says, “I see the house where I
was born, the trundle bed in my mother's room where I

37. used to sleep e I can even see my mother as she comes to
tuck me in and I can even hear her voice as she softly says
goodnight”? Touching, of course, but sheer bunk. We are
merely dramatizing. The behaviourist finds no proof in
imagery in all this. We have put these things in words long,
long ago and we constantly rehearse those scenes verbally
whenever the occasion arises’
John B Watson
y, University of New Sou
(R. Keogh).
rved.
The study of visual imagery has been a controversial topic
for many years, as the above quote from the behaviourist John
Watson demonstrates. This quote exemplifies the long
running imagery debate of the 1970s and 80's, which centred on
the question of whether imagery can be depictive in the format
of its representation (Kosslyn, 2005), or only symbolic or
propositional in nature (Pylyshyn, 2003). However, in the last
few decades psychologists and neuroscientists have made
great strides in showing that visual imagery can be measured

38. objectively and reliably, and indeed can be depictive/pictorial
in nature, see Pearson and Kosslyn (2015) for a detailed
th Wales, Sydney, Australia.
mailto:[email protected]
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.10.012&domain=pdf
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www.elsevier.com/locate/cortex
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discussion of the evidence. Research has shown that visual
imagery, like weak perception, impacts subsequent perception
in a myriad of ways (Ishai & Sagi, 1995; Pearson, Clifford, &
Tong, 2008; Winawer, Huk, & Boroditsky, 2010; Zamuner,
Oxner, & Hayward, 2017). For example, the effect of imagery
on subsequent rivalry is specific in orientation and location
space, showing strong evidence for a depictive representation
(Pearson et al., 2008). Imagery has also been shown to activate
early visual cortex and the content of imagery can be decoded

39. in these areas using an encoding model based on low-level
depictive visual features, such as spatial orientation and
contrast (Naselaris, Olman, Stansbury, Ugurbil, & Gallant,
2015), and recently using features based on a multi-level con-
volutional neural network (Horikawa & Kamitani, 2017).
Additionally, visual imagery has been shown to be closely
related to many cognitive functions such as visual memory
(Albers, Kok, Toni, Dijkerman, & de Lange, 2013; Keogh &
Pearson, 2011, 2014), spatial navigation (Ghaem et al., 1997),
language comprehension (Bergen, Lindsay, Matlock, &
Narayanan, 2007; Zwaan, Stanfield, & Yaxley, 2002), making
moral decisions and making a decision to help others (Amit &
Greene, 2012; Gaesser & Schacter, 2014). Visual imagery also
appears to be elevated (stronger or more vivid) in some psy-
chological and neurological disorders (Matthews, Collins,
Thakkar, & Park, 2014; Sack, van de Ven, Etschenberg,
Schatz, & Linden, 2005; Shine et al., 2015). Visual imagery
has even been employed to assist in cognitive behavioural

40. therapies such as imaginal exposure and imaginal rescripting
(Arntz, Tiesema, & Kindt, 2007; Holmes, Arntz, & Smucker,
2007; Pearson, Naselaris, Holmes, & Kosslyn, 2015) and the
use of visual imagery during cognitive behavioural therapy
has been shown to be more effective than just verbal pro-
cessing (Pearson et al., 2015).
With strong evidence that visual imagery can be a depictive
cognitive mechanism, the question arises, were Watson,
Pylyshyn and their ilk wrong? Or is it possible that they had a
distinctly different experience of visual imagery that was not
depictive, but more propositional or phonological in nature?
Interestingly, a study investigated exactly this idea and found
that those researchers who were more likely to have been on
the ‘imagery is depictive’ side of the debate tended to report
more vivid imagery, while those who reported weaker imag-
ery were more likely to be on the imagery is propositional side
of the debate (Reisberg, Pearson, & Kosslyn, 2003). One of the
hallmarks of visual imagery is the large range of subjective

41. reports in the vividness of an individual's imagery. For
example, when people are asked to imagine the face of a close
friend or relative some people report imagery so strong it is
almost akin to seeing that person, whereas others report their
imagery as so poor that, although they know they are thinking
about the person, there is no visual image at all. Sir Francis
Galton gave one of the earliest accounts of these subjective
differences in visual imagery in 1883. Galton devised a series
of questionnaires asking participants to imagine a specific
object then describe the ‘illumination’, ‘definition’ and ‘col-
ouring’ of the image. He found, to his surprise, that many of
his fellow scientists professed to experience no visual images
in their mind at all: ‘To my astonishment, I found that the
great majority of the men of science to whom I first applied
protested that mental imagery was unknown to them, and
they, looked on me as fanciful and fantastic in supposing that
the words “mental imagery” really expressed what I believed
everybody supposed them to mean. They had no more notion
of its true nature than a colour-blind man, who has not dis-

42. cerned his defect, has of the nature of colour. They had a
mental deficiency of which they were unaware, and naturally
enough supposed that those who affirmed they possessed it,
were romancing.” In recent years very little attention has been
given to the ‘poor’ or non-existent side of the visual imagery
spectrum, outside of participants with neurological damage.
Much research during the imagery debate of the 70's and 80's
revolved around brain damaged participants who had lost
their ability to imagine, but retained their vision, or vice versa
(Farah, 1988). Recently the idea that some people are wholly
unable to create visual images in mind, without any sort of
neurological damage, psychiatric or psychological disorders,
has seen a resurgence. A recent paper by Zeman, Dewar, and
Della Sala (2015) coined a term for this phenomenon
‘congenital aphantasia’. This study found that these aphan-
tasics all scored very low on the vividness of visual imagery
questionnaire (VVIQ). The VVIQ is a commonly used ques-
tionnaire to measure the subjective vividness of an in-

43. dividual's visual imagery, by asking them to imagine a friend
or relative, as well as scenes and rate the vividness of these
images on a Likert scale. However, a case study reported a 65-
year-old male who became aphantasic after surgery (without
any obvious neurological damage) and was still able to
perform well on other measures of visual imagery, such as
answering questions about the shape of animal's tails. The
patient was also able to perform two types of mental rotation
tasks (manikin and ShepardeMetzler tasks), which are
commonly used test of imagery ability (A. Z. Zeman et al.,
2010). Interestingly, his reaction times however, did not
correspond to the rotation distance, which is the common
finding in the literature. These reports suggest the possibility
that aphantasic individuals do actually create images in mind
that they are able to use to solve these tasks, however they are
unaware of these images; that is they lack metacognition, or
an inability to introspect.
Although the visual imagery tasks used in the Zeman et al.
(2010) study are used extensively throughout the imagery

44. literature, and in clinical settings to measure visual imagery,
the validity of these tasks are somewhat unclear. For example,
in the animal tails test it may be that subjects can use prop-
ositional semantic information about the images they are
asked to imagine, instead of actually creating a visual image in
mind. Additionally, the mental rotation task used (manikin
and ShepardeMetzler tests) could be performed using spatial,
or kinaesthetic imagery, rather than ‘low-level’ visual object
imagery. A relatively new experimental imagery task, which
exploits a visual illusion known as binocular rivalry, allows us
to eliminate many of the issues related to these visual imagery
measures (Pearson, 2014). Binocular rivalry is an illusion, or
process, where one image is presented to the left eye and a
different image to the right, which results in one of the images
becoming dominant while the other is suppressed outside of
awareness (see Fig. 1A for illustration). Previous work has
demonstrated that presenting a very weak visual image of one
of the rivalry patterns prior to the presentation of the binoc-

45. ular rivalry display, results in a higher probability of that
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impacts of weak visual imagery
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cognitive functions related to visual imagery:
- Visual memory
-Spatial navigation
-language comprehension
-moral decision making
-Some psychological and neurological disorders
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image being seen in the subsequent binocular rivalry pre-
sentation (Brascamp, Knapen, Kanai, van Ee, & van den Berg,
2007; Pearson et al., 2008). Interestingly, when someone
imagines an image instead of being presented with a weak
one, a very similar pattern of results emerges. In other words,
imagery can prime subsequent rivalry dominance much like
weak visual perception (Pearson, 2014; Pearson et al., 2008).
Hence, this imagery paradigm has been referred to as a
measure of the sensory strength of imagery, as it bypasses the
need for any self-reports and directly measures sensory
priming from the mental image.

47. If an individual is presented with a uniform and passive lu-
minous background while they generate an image, the facilita-
tive effect of their mental image is reduced (Chang, Lewis, &
Pearson, 2013; Keogh & Pearson, 2011, 2014, 2017; Sherwood
&
Pearson, 2010). Previous work has shown that these disruptive
effects are limited to visual tasks that require the use of depic-
tive image generation (Keogh & Pearson, 2011, 2014)
suggesting
that the early visual areas of the brain are likely involved in the
construction and maintenance of these images. Further, this
priming effect is local in both retinotopic spatial-locations and
orientation feature space (Bergmann, Genç, Kohler, Singer, &
Pearson, 2015; Pearson et al., 2008), further suggesting the
priming is contingent on early visual processes.
This measure of visual imagery also correlates with sub-
jective ratings of visual imagery, both trial-by-trial and ques-
tionnaire ratings, suggesting that participants have insight
into the strength of their own visual imagery (Bergmann et al.,

48. 2015; Rademaker & Pearson, 2012). Here we ran a group of
selfedescribed congenital aphantasics on the binocular ri-
valry visual imagery paradigm to measure the strength of
their sensory imagery. If congenital aphantasia is a complete
lack of visual imagery, we should expect no facilitative prim-
ing effects of visual imagery on subsequent rivalry. However,
if congenital aphantasia is instead a lack of metacognition, or
failed introspection, then we may expect to observe some
priming, despite the subjective reports of no imagery. We
further, tested the aphantasics on a range of standard
Fig. 1 e Binocular rivalry and experimental timeline. A.
Illustration o
images are presented, one to each eye, instead of seeing a mix
of
Fluctuations only occur for prolonged viewing, not for our brief
riv
Participants were cued to imagine one of two images (r ¼ red-
hor
Participants imagined this image for 6 sec, then after 6 sec they
ra
After this they were presented with a very brief binocular
rivalry d

49. questionnaires to probe the vividness and spatial qualities of
their imagery.
1. Methods and materials
1.1. Participants
Fifteen (aged 21e68, 7 female) self-described aphantasic par-
ticipants completed all experiments and questionnaires. The
Aphantasics were recruited through a Facebook page, had
emailed the lab regarding their aphantasia or were referred to
us by Adam Zeman. All aphantasic participants indicated that
they could not remember a time they could imagine and there
was no injury that had led them to becoming aphantasic. We
did not however do a full neurological exam of the partici-
pants. The control, or ‘general population’ group uses data
that was collected over numerous experiments, some of
which were published in a number of different journal articles
(see Keogh & Pearson (2011, 2014); Shine et al. (2015)): while
some are as yet unpublished, all using the same binocular
rivalry visual imagery task, with the exact same stimuli and
instructions, however not all of the studies included vividness

50. ratings; the sample contains 209 different individuals. The age
range of these 209 participants is from young adult (18 years þ)
to elderly (80's). All participants had normal or corrected to
normal vision (i.e., wore glasses or contacts).
Fifteen control participants also completed the OSIQ (age
range 18e35, 10 female).
1.2. Stimuli
All participants (in the aphantasic and general population)
were tested in blackened rooms with the lights off, and their
viewing distance from the monitor was 57 cm and was fixed
with the use of a chin rest. The data for the general population
were collected over several years and used several different
computer monitors and testing rooms, as such the stimuli
f an extended binocular rivalry presentation. Two separate
the two, perception alternates between the two images.
alry presentation. B. Binocular rivalry experimental timeline.
izontal Gabor patch and g ¼ green-vertical Gabor patch).
ted how vivid the image they created was on a scale of 1e4.
isplay (750 msec) and had to report which colour they saw.
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parameters will all be slightly different, due to monitor and
graphics card differences. However, all the experiments were

52. performed by the same experimenter (RK), who ran all par-
ticipants in the aphantasia and general population studies.
The following specific stimuli parameters described, are for
the aphantasic participants of this study.
In the imagery task the binocular rivalry stimuli consisted
of red horizontal (CIE x ¼ .57, y ¼ .36) and green vertical (CIE
x ¼ .28, y ¼ .63) Gabor patterns, 1 cycle/�, Gaussian s ¼ 1.5�.
Gabor patterns are sinusoidal gratings with a Gaussian enve-
lope applied. The patterns were presented in an annulus
around the fixation point and both Gabor patterns had a mean
luminance of 4.41 cdm2. The background was black
throughout the entire task during the no luminance condition.
For the imagery luminance condition the background ramped
up to yellow (a mix of the green and red colours used for the
rivalry patterns, with luminance at 4.41 cdm2), during the six-
second imagery period. During this period the background
luminance was smoothly ramped up and down to avoid visual
transients, which may result in attention being directed away
from the task.

53. Mock rivalry displays were included on 12.5% of trials to
assess any effects of decisional bias in the imagery task. One
half of the mock rivalry stimuli was a red Gabor patch, with
the other half being a green Gabor patch (a spatial mix) and
they shared the same parameters as the green and red Gabor
patches mentioned in the previous paragraph. The mock ri-
valry stimuli were spatially split with blurred edges and the
exact division-path differed on each catch trial (random walk
zigezag edge) to resemble actual piecemeal rivalry. The
aphantasic participants mock priming was not significantly
different to 50% (t(14) ¼ 1.08, p ¼ .30), indicating a lack of
decisional priming.
1.3. Experimental procedure
All aphantasic participants came to the University of New
South Wales to participate in approximately 3 h of testing.
They were reimbursed $15 AUD per hour for their participa-
tion in the study. At the beginning of the experimental session
they were briefed verbally about the study (they were told they

54. were going to fill-in some questionnaires, see some visual il-
lusions, do some memory tests and imagine some pictures)
and written informed consent was obtained. The participants
then completed the following questionnaires and binocular
rivalry task (lasting for about 1e1.5 h) as well as completing
some other memory and imagery tasks for a different study,
not reported on here.
1.4. Questionnaires
All participants completed the vividness of visual imagery
questionnaire (VVIQ2) (Marks, 1973), spontaneous use of im-
agery scale (SUIS) (Reisberg, Culver, Heuer, & Fischman,
1986),
and the object and spatial imagery questionnaire (OSIQ)
(Blajenkova, Kozhevnikov, & Motes, 2006). The VVIQ asks
participants to imagine several scenes and then rate how vivid
their imagery is for each item on a scale of 1e5; with 1 ¼ ‘No
image at all, you only “know” that you are thinking of the
object’ and 5 ¼ ‘Perfectly clear and vivid as normal vision’.
Both the SUIS and the OSIQ give participants statements and
they have to rate how much they agree with the statement

55. from 1 to 5, with 1 ¼ ‘totally disagree’ and 5 ¼ ‘totally agree’.
An example question from the SUIS is: ‘When I hear a radio
announcer or DJ I've never actually seen, I usually find myself
picturing what they might look like’.
1.5. Binocular rivalry task
Before completing the binocular rivalry imagery task each
participant's eye dominance was assessed (for a more in depth
explanation see Pearson et al. (2008)) to ensure rivalry domi-
nance was not being driven by pre-existing eye dominance, as
this would prevent imagery affecting rivalry dominance.
Following the eye dominance task participants completed
either 2 or 3 blocks of 40 trials depending on time constraints
and number of mixed percepts. Mixed percept trials were not
analysed here, so for this reason we attempted to have at least
60 analysable trials per participant, however due to time
constraints and mixes, 4 participants only completed 32, 34,
35, and 45 trials. There was however no correlation between
the number of trials completed and rivalry priming (rs ¼ .04,
p ¼ .90, Spearman's correction for non-normality), hence these
participants' data are included in the analysis. Participants
also completed 2 or 3 blocks of 40 trials of the binocular rivalry

56. task with a luminous background during the imagery period.
Binocular rivalry imagery paradigm: Fig. 1B shows the time-
line of the binocular rivalry imagery experiment. At the
beginning of each trial participants were presented with
either an ‘R’ or a ‘G’ which cued them to imagine either a red-
horizontal Gabor patch (‘R’) or a green-vertical Gabor patch
(‘G’). Following this, participants were presented with an im-
agery period of 6 sec. In the no luminance condition the
background remained black during this imagery period, in the
luminance condition the background ramped up and down to
yellow over the first and last second of the 6 sec imagery
period to avoid visual transients. After this 6 sec period par-
ticipants were asked to rate how ‘vivid’ the image they
imagined was on a scale of 1e4 (using their left hand on the
numbers on the top of the keyboard) with ‘1’ ¼ ‘No image at
all, you only “know” that you are thinking of the object’ and
‘4’ ¼ ‘Perfectly vivid’. After this they were presented with a
binocular rivalry display comprising the red-horizontal and
green-vertical Gabor patches and asked to indicate which

57. image they saw most, of using their right hand on the key pad:
‘1’ ¼ green-vertical, ‘2’ ¼ perfectly mixed, ‘3’ ¼ red-
horizontal.
2. Results
Table 1 and Fig. 2AeC show participants' scores on the visual
imagery questionnaires. The data supports Zeman et al. (2015)
findings that aphantasic participants rate their imagery as
very poor or non-existent on the VVIQ. These data also show
that participants also rate their spontaneous use of visual
imagery as very low on both the SUIS and Object component
of the OSIQ. Interestingly, the aphantasic participants' spatial
component of the OSIQ was almost double that of their object
score. To further assess this finding 15 non-age matched
participants also completed the OSIQ. There was a significant
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Table 1 e Average scores on visual imagery questionnaires for
the aphantasic participants.
Object OSIQ/75 Spatial OSIQ/75 VVIQ/80 SUIS/60

58. Total score mean 21.53 41.80 19.00 17.20
Standard deviation 3.46 10.33 6.78 1.65
Fig. 2 e Frequency Histograms for aphantasic participants
scores on the VVIQ (Bins ¼ 2) (A), SUIS (Bins ¼ 2) (B) and
Object
components of the OSIQ (Bins ¼ 2) (C). D. Object and spatial
scores on the OSIQ for aphantasic (white bars) and control
participants (grey bars). E. Frequency histogram for imagery
priming scores for aphantasic participants (yellow bars and
orange line) and general population (grey bars and black dashed
line), (Bins ¼ 5). The green dashed line shows chance
performance (50% priming). F. Average priming scores for
aphantasic participants in the no background luminance
condition (dark grey bar), aphantasic participants in the
background luminance condition (white bar) and general
population with no background luminance (light grey bar). G.
Mean ‘online’ trial-by-trial vividness ratings for aphantasic
participants in the no background luminance (grey bars) and
luminous background condition (white bar). H. Frequency
histogram of Bootstrapping from the general population data
(Bins ¼ 1). 15 subjects were randomly chosen, averaged, then
returned to the main pool of subjects. Data shows the
distribution of the mean of N ¼ 15 for 1000 iterations. The
aphantasic
mean is shown on the far left (orange dotted line), with a P ¼
.001 chance of pulling such a mean from the general
population. All error bars show ±SD's

59. c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 0 57
interaction between the spatial and object components of the
OSIQ and the participant group (aphantasic/control), Mixed
repeated measures ANOVA: F(1, 28) ¼ 45.25, p < .001 (see
Fig. 2D). Post hoc analysis of the simple effects demonstrated
that as expected the aphantasic participants rated their use of
spontaneous object imagery as significantly lower than the
controls (p < .001). The aphantasics self-rated spontaneous
use of spatial imagery was not significantly higher than the
controls (p ¼ .15), mean scores: Aphantasic ¼ 41.80 and
control ¼ 36.53.
Next the binocular rivalry imagery priming scores were
examined. As can be seen in Fig. 2E and F, aphantasics had
significantly lower priming on average than our general
sample of participants (ManneWhitney U ¼ 914, p < .01, 2-
tailed). In fact, the aphantasic group's priming scores were not
significantly different from chance (50%) (Fig. 1E grey filled
bar,
one sample t-test: t(14) ¼ .68, p ¼ .51), unlike the general
population whose mean is significantly different to chance
(one sample t-test: t(208) ¼ 10.96, p < .001). There were also
no
correlations between visual imagery priming for the aphan-

60. tasic participants and any of the questionnaire measures,
likely due to a restriction of range (all p's >. 37). Additionally,
when aphantasic participants completed the task with a lu-
minous background during the imagery period, their priming
was no different to priming in the no luminance condition
(paired sample t-test: t(14) ¼ 1.10 p ¼ .29) and was again not
significantly different from chance (one sample t-test:
t(14) ¼ 1.75, p ¼ .10). These results suggest that the aphantasic
participant's imagery has little effect on subsequent binocular
rivalry. Aphantasic participants' mean ‘online’ trial-by-trial
vividness ratings were also very low, with the average rat-
ings not significantly different from the lowest rating of 1 (one
sample t-tests: no luminance condition: t(14) ¼ 1.18, p ¼ .36,
luminance condition: 1.37, p ¼ .19, see Fig. 2G). The vividness
ratings were not different between the no luminance and
luminance conditions (paired sample t-test: t(14) ¼ 1.10,
p ¼ .29).
One possible explanation for the observed differences be-
tween aphantasics and the general population may be that the
eye dominance test simply did not adequately work for the
aphantasic group, thus preventing any imagery priming. If a
participant naturally has one eye that dominates over the

61. other, this will result in them only seeing the one image that is
presented to that dominant eye e which will result in chance
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c o r t e x 1 0 5 ( 2 0 1 8 ) 5 3 e6 058
levels of priming. At the beginning of the imagery experiment
all participants complete an eye dominance task to assess
which eye is dominant. The contrast of the red and green
Gabor patches are then adjusted in accordance with the par-
ticipant's eye dominance, e.g., if the participant sees more
green/has a stronger left eye, the contrast of the green Gabor
patch will be decreased, while the red Gabor patch is
increased. This results in each participant having different eye
dominance values. To assess whether eye dominance differ-
ences might be driving our effect, or lack of effect, we
compared eye dominance values (red and green contrasts)
used for the aphantasic participants with 15 other partici-
pants randomly drawn from the general population pool. We
found that there was no significant difference in the eye

62. dominance values for the aphantasic and control participants,
with no interaction between the …
www.sciencedirect.com
c o r t e x 1 0 5 ( 2 0 1 8 ) 4 1 e5 2
Available online at
ScienceDirect
Journal homepage: www.elsevier.com/locate/cortex
Special issue: Research report
(A)phantasia and severely deficient
autobiographical memory: Scientific and personal
perspectives
Nicholas W. Watkins a,b,c,*
a Centre for the Analysis of Time Series, London School of
Economics and Political Science, London, UK
b Faculty of Science, Technology, Engineering & Mathematics,
School of Engineering & Innovation, Open University,
Milton Keynes, UK
c Centre for Fusion, Space and Astrophysics, University of
Warwick, Coventry, UK
a r t i c l e i n f o
Article history:
Received 26 February 2017
Reviewed 6 May 2017
Revised 5 July 2017

63. Accepted 15 October 2017
Published online 7 November 2017
Keywords:
Episodic memory
Severely deficient autobiographical
memory
Mental imagery
Aphantasia
Mind's eye
* Centre for the Analysis of Time Series, L
E-mail address: [email protected]
https://doi.org/10.1016/j.cortex.2017.10.010
0010-9452/© 2017 Elsevier Ltd. All rights rese
a b s t r a c t
I address two interlinked aspects of the diversity in our
experiences of memory and the
mind's eye. I summarise the long-appreciated role of imagery in
mathematics and the
physical sciences, and contrast it with the evidence that some
scientists have had limited
or zero imagery. I then recount the story of how I became aware
of my own lack of mental

64. imagery, and the accompanying deficit in my episodic memory,
how I have sought sci-
entific understanding of these conditions, and how they have
affected my life.
© 2017 Elsevier Ltd. All rights reserved.
1. Introduction
The contributions in this special issue touch on many of the
areas of human creativity in which visual imagery has played
a key role, and my paper, derived from my contribution to the
“Eye's Mind” conference in 2016 supported by the AHRC, aims
first to briefly survey the role of imagery in mathematics and
the physical sciences, but it also has a second, more personal
aim.
ondon School of Econom
rg.
rved.
Three human visual capacities are so familiar that most
people take them for granted: i) visual imagination in a
“mind's eye”, ii) an “episodic” aspect to memory that travels
back in time to give a first person sense of experiencing again
one's own past sights, sensations and emotions, and iii) its
opposite, first person “mental time travel” into an anticipated
future. But we really shouldn't be so blas�e. Indeed it has been

65. argued (Tulving, 2002) that episodic memory and the first-
person sense of time are among the most remarkable
ics and Political Science, Houghton St, London, WC2A 2AE,
UK.
mailto:[email protected]
http://crossmark.crossref.org/dialog/?doi=10.1016/j.cortex.2017
.10.010&domain=pdf
www.sciencedirect.com/science/journal/00109452
www.elsevier.com/locate/cortex
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products of evolution. Because the faculties noted above are
so universal, they can be taken to be essential aspects of being
human, but in the last two years it has become much more
widely appreciated that a significant number of people actu-
ally lack mental imagery (“aphantasia”; Zeman, Dewar, &
Della Sala, 2015), and that some otherwise healthy people
have severely deficient autobiographical memory (SDAM;
Palombo, Alain, Soderlund, Khuu, & Levine, 2015). I am one
such person. I have been aware of my aphantasia and SDAM,
and I have been seeking to understand the reasons behind

66. them for almost 20 years. The rest of this paper gives a report
of my findings (albeit an unusual one in which first person
testimony will figure large).
2. Scientific aspects
The role of the nearly universal human faculty of mental
imagery (Kosslyn, 1994; MacKisack et al., 2016; Pearson,
Deeprose, Wallace-Hadrill, Burnett Heyes, & Holmes, 2013;
Thomas, 1997) in scientific and mathematical creativity has
long attracted research interest (Brewer & Schommer-Aikins,
2006; Ferguson, 1977; Hadamard, 1945; Mancosu, Joergensen,
& Pedersen, 2005; Miller, 1986; Rocke, 2010). Probably the
most
celebrated instance is the physical chemist Kekule's account
(Benfy, 1958; Rocke, 2010) of how he dreamt the structure of
the benzene ring: “long rows, … all twining and twisting in
snake-
like motion … One of the snakes had seized hold of its own tail,
and
the form whirled mockingly before my eyes. As if by a flash of
lightning I awoke; and … spent the rest of the night in working
out

67. the consequences of the hypothesis” (Benfy, 1958). By his own
account, such visualisation was a frequently exercised fac-
ulty, his “mental eye” having been “rendered more acute by
repeated visions of the kind”. The benzene dream was
apparently
preceded by an earlier daydream on a London bus about
chemical valence, where “the atoms were gamboling before my
eyes” (Benfy, 1958).
Many physicists have employed visualisation, for example
space scientist Jim Dungey, interviewed in 1986 saying “I saw
the picture … in three dimensions, whereby the electric field
over the
polar cap fitted in with the reconnection picture … Then, I think
if I
can, everybody can” (Dungey, 1986). Albert Einstein seems to
have been an archetypal visualiser. His most famous thought
experiment, to imagine riding alongside a beam of light, was
conducted as a 16-year old student at a Pestalozzi school in
Switzerland (Isaacson, 2015). Many years later he responded

68. to a questionnaire about scientific creativity by the French
mathematician Jacques Hadamard [see Appendix II of
Hadamard (1945)] by saying The psychical entities which seem
to
serve as elements in thought are … more or less clear images
which
can be ‘voluntarily’ reproduced and combined. [Some are] of
visual
and some of muscular type. Conventional words or other signs
have
to be sought for laboriously only in a secondary stage.”
Pauli even went as far as collaborating with Jung to
investigate the latter's “primordial images” as the bridge be-
tween sense perceptions and concepts (Zabusky, 1984). How-
ever, even enthusiastic users of mental imagery have urged
caution. Kekule, after all, warned us to “beware of publishing
our
dreams until they have been tested by the waking
understanding”.
Although Farmelo (2009) reports that Dirac was “always uneasy
with algebraic approaches to physics and with any mathematical
process he could not picture”, it is striking that he nonetheless

69. prefaced his “Principles of Quantum Mechanics” by saying:
“the laws of physics do not govern the world as it appears in our
mental picture in any very direct way, but instead they control a
substratum of which we cannot form a mental picture without
introducing irrelevancies” (Dirac, 1930). Although Feynman
greatly admired Dirac, his famous diagrams were a direct
response to the latter's implicit challenge to find a pictorial
tool that could be of value in quantum mechanics (Wuetrich,
2010).
The training of physicists recapitulates the historical pro-
cess, and generations of students have struggled with the
transition between Newtonian mechanics and Maxwell's
electrodynamics, where many concepts benefit greatly from
visualisation, and quantum mechanics, a theory constructed
using objects as foreign to our direct sensory experience and
intuition as the probability amplitude wavefunction which
solves Schrodinger's equation (e.g., Longair, 2003; Miller,
1986).
The rigour exemplified by the scientific method is of course
essential to making science as objective as possible, by

70. detaching its conclusions from the thought processes of any
one individual, no matter how exceptional, and subjecting
them to experimental test. In mathematics, where proof
rather than experiment is the final arbiter, an even more
fundamental disdain for visualisation has existed in some
quarters. Lagrange for example proudly said “you won't find
any
drawing in my book”, while the collective of French mathema-
ticians who published as “Nicolas Bourbaki” sought to elimi-
nate any need for visualization, part of a broader distrust of
geometry in proof. In Marjorie Senechal's interview (Senechal,
1998), Bourbaki founder member Pierre Cartier gives this
fascinating reply to her question about the sources of this
disdain: “… The Bourbaki were Puritans, and Puritans are
strongly
opposed to pictorial representations of truths of their faith. […]
So,
what were the reasons? The general philosophy as developed by
Kant, certainly. […] And then there was the idea that there is an
opposition between art and science. Art is fragile and mortal,
because it appeals to emotions, to visual meaning, and to

71. unstated
analogies. But I think it's also part of the Euclidean tradition. In
Euclid, you find some drawings but it is known that most of
them
were added after Euclid, in later editions. Most of the drawings
in the
original are abstract drawings. You make some reasoning about
some proportions and you draw some segments, but they are not
intended to be geometrical segments, just representations of
some
abstract notions. […] The analytical spirit was part of the
French
tradition and part of the German tradition. And I suppose it was
also
due to the influence of people like Russell, who claimed that
they
could prove everything formallydthat so-called geometrical
intui-
tion was not reliable in proof.”
In stark contrast to the Bourbaki was a mathematical
visionary (and visualiser) Benoit Mandelbrot, whose own
uncle was one of the founders of the Bourbaki, and whose

72. life's work was in some sense a riposte to their approach.
Describing the way in which he mastered mathematics as a
teenager he said: “I didn't learn much algebra. I just learnt how
better to think in pictures because I knew how to do it. I would
see
them in my mind's eye intersecting, moving around or not inter-
secting and could describe what I saw. Having described it, I
could
write two or three lines of algebra, which, is much easier if you
know
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the results than if you don't” (Mandelbrot, 1995). In later years
Mandelbrot's very visual approach enabled him to see deep
geometrical links between mathematics and disciplines
including physics, economics and the geosciences that few
people would have connected, but this very farsightedness
seems to have made it difficult for him to explain what he had
seen, Mandelbrot (2012) and some innovations of his from 50
years ago are only now being rediscovered, a process
described by Watkins (2016).

73. However, the process of science is not just deduction by
individuals but construction by a community. The remarkable
geometric abilities of some blind mathematicians such as
Morin have given insight into the varieties of mathematical
imagination and quite how diverse this community is. Morin
himself noted that “disabilities like blindness, … reinforce one's
gifts and one's deficits” and has drawn attention to two sorts of
mathematical imagination: “time-like” which deals with in-
formation by proceeding through a series of steps, at which he
was not good, a deficit worsened by blindness, and “space-like”
which allows one to comprehend information all at once, at
which he excelled (Lawrence, 2002).
Much of the work on mental imagery in science has either
concerned naturally strong imagers or people who have lost
sight while retaining (or losing) a “mind's eye”. The famous
work of Galton (1880, 1883) recounted by James (1890), thus
remains a particularly important exception. The responses of
some recipients of his questionnaire: “amazed [him]. [He] had
begun by questioning friends in the scientific world, as they
were the

74. most likely class of men to give accurate answers concerning
this
faculty of visualising, to which novelists and poets continually
al-
lude, which has left an abiding mark on the vocabularies of
every
language … ” He was astonished to find that “the great majority
[sic] of the men of science to whom [he] first applied protested
that
mental imagery was unknown to them, and they looked on [him]
as
fanciful and fantastic in supposing that the words ‘mental
imagery’
really expressed what [he] believed everybody supposed them to
mean.” When Galton extended these first approaches to a
larger sample of 100 “men of science”, the majority did not in
fact lack imagery but even so up to six of his respondents
seem to have reported themselves to be truly without expe-
riences of visual imagery. The work of Burbridge (1994) has
made it possible to establish who they were: “(95, Charles
Piazzi
Smyth). No power of visualising … (96, Major John Herschel

75. FRS). It
is only as a figure of speech that I can describe my recollection
of a
scene as a ‘ mental image’ which I can ‘ see’ with my ‘ mind's
eye.’
(97, Sir Edmund Du Cane). No individual objects, only a
general idea
of a very uncertain kind. (98, George John Romanes FRS). …
My
memory is not of the nature of a spontaneous vision, … ideas
are not
felt to be mental pictures, but rather the symbols of facts. (99,
Sir
James Paget FRS). … impressions are in all respect so dim
vague and
transient, that I doubt whether they can reasonably be called
images.
They are incomparably less than those of dreams. (100, Sir J.
Henry
Lefroy FRS). My powers are zero. To my consciousness there is
almost no association of memory with objective visual
impressions. I
recollect the breakfast table, but do not see it.”
It is striking that James (1890) seems to have completely

76. accepted Galton's findings, saying that some people “un-
doubtedly have no visual images at all worthy of the name, and
instead of seeing their breakfast-table, they tell you that they
remember it or know what was on it. This knowing and
remembering takes place undoubtedly by means of verbal
images”.
Faw (2009) argues that both Galton and James may have had
relatively weak imagery themselves. Galton reported that he
could only visualise with effort; saying that “before [he]
thought of
carefully trying, [he] should have emphatically declared that
[his]
field of view in the dark was essentially of a uniform black,
subject to
an occasional light-purple cloudiness and other small
variations”
(Galton, 1883). However, after Galton's efforts to “habituat[e
him]self to examine it with the same sort of strain that one tries
to
decipher a signpost in the dark, [he] found out that this is by no
means the case, but that a kaleidoscopic change of patterns and
forms is continually going on, but they are too fugitive and
elaborate

77. … to draw with any approach to truth.” Even after practise, they
“disappear out of sight and memory the instance [he began] to
think
about anything …”, a finding which greatly interested
Hadamard (1945), who was concerned with whether images
accompanied thought or were antithetical to it, as he felt to be
the case for himself. Even Galton's critic, Bain (1880) agreed
that there was a “natural antagonism of pictorial aptitude and
abstract thought”.
James' enthusiasm may not have been typical, and
Burbridge (1994) notes that Galton's work in general encoun-
tered a mixed response among his peers. Galton (1880)
attracted a hostile comment from Bain (1880) almost imme-
diately: “At first blush it seems to be nothing more than a deter-
mination, by accurate statistics, of the relative preponderance of
certain varieties of mind that we already know to exist. … That
certain individuals … have a great or a small visualising
memory, is
an important fact as regards them … [but] it contributes nothing
new
to science; the existence of such variations has been known at

78. all
times [my emphases]”. Burbridge (1994) shows that Galton was
indeed aware of previous interest in the range of individual
differences from Fechner, Erasmus Darwin and (Wilhelm)
“Wundt of Heidelberg” but it is not clear that they had noticed
the existence of non-imagers before him.
Despite his paper's scathing tone, Bain's plea for a more
balanced appraisal remains relevant today: “The ear plays a
part in our intellectual being second only to sight; the power of
language is the rival power to visual conception, and, in the
texture
of the memory, may take its place. Something, therefore, should
be
known respecting the linguistic memory also, without which no
statement of the intellectual peculiarity of the individual is
com-
plete”. Indeed, Paivio's celebrated Dual Coding Theory (Paivio,
1971, 1990, 2007) offers a modern approach to the very
image-word dichotomy that Bain was referring to. It was
characterized by one of my reviewers as “a synthesized view
that is inclusive with both the imaginal and verbal systems

79. playing
prominent roles. … [it] challenges the compartmentalized,
either/or
semantic vs. imagery view of cognition and instead advocates a
proposition that the secret lies in the unification of the two
great
coding systems for efficacious memory and higher order levels
of
cognition”.
The new findings of Zeman et al. (2015), taking up the
enquiry started by Galton, are already giving rise to de-
velopments in many directions. I would like to propose that
one avenue should be to ask how the wide spectrum of mental
imagery among scientists may have affected the evolution of
science itself, informed by the growing awareness that im-
agery can be low or absent as well as strong. I am presently
aware of only a very few documented living aphantasic
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80. scientists or technologists, with perhaps the highest profile
examples being geneticist Craig Venter (Grinnell, 2016) and
software engineer Blake Ross (Ross, 2016). The past is not
much more illuminating, although we do know who Galton's
aphantasic respondents were. In view of this paucity of in-
formation, I will give a brief account in the next section of how
I became aware of my own aphantasia, and of my concurrent
SDAM, noting some of the wide variety of published material
which helped me during my search for more insights, and
offering some thoughts on how it has affected me in my work
in physics. I hope that even this limited data point will be of
some value to this nascent area of research. I also think that
an account of how I became aware of my situation in a time
before widespread awareness of SDAM and aphantasia may
already be of some historical and “control” value in itself.
3. Personal aspects
“I saw it in my mind's eye” … “it took me right back” …”where
do
you see yourself in 5 years' time?”. These phrases are so
familiar
that most people take for granted the three human capacities

81. they embody: visual imagination; “episodic” memory that
directly re-experiences one's own past sights, sensations and
emotions; and its temporal opposite, first person “mental time
travel” into an anticipated future. Most people, but not all, as
was apparently first noticed by Galton (1880) and is now
becoming clearer through the work of Palombo et al. (2015) on
SDAM and Zeman et al. (2015) on aphantasia. I am somebody
who lacks all these three capacities, and the rest of this paper
is about my quest, both as a physicist and a person, to un-
derstand why, and to come to terms with these differences.
But first, in answer to the reader's inevitable questions, I will
try to describe what, for me, it is like to be aphantasic and to
have SDAM, though I must caution that mine may not be
representative of other people's experiences.
I think the best way I can describe my aphantasia is to say
that I am unaware of anything in my mind except these cat-
egories: i) direct sensory input, ii) “unheard” words that carry
thoughts, iii) “unheard” music, iv) a kind of “invisible imag-
ery”, which I can best describe as sensation of pictures that are
in a sense “too faint to see”, v) emotions, and vi) thoughts

82. which seem too “fast” to exist as words. The “invisible imag-
ery” is a sensation of having an image that one feels to be
there but one can't see, as opposed to, say, a faint image like
the “misty watercolour memories” of the song “The Way We
Were”. I felt a kinship with the description of his own sub-
liminal imagery by Faw (2009). I see what is around me, unless
my eyes are closed when all is always black. I hear, taste, smell
and so forth, but I don't have the experience people describe of
hearing a tune or a voice in their heads. Curiously, I do
frequently have a tune going around in my head, all I am
lacking is the direct experience of “hearing” it. I think the
likely effect of aphantasia on me is to increase my reliance on
the verbal over the visual, and to enhance my interest in the
abstract rather than the concrete. I have an ability to jump
between concepts very easily, but people have commented
that I often forget to explain how these apparently frictionless
leaps happened. I think it may have contributed to making me
more interested in questions than answers, and problems
rather than solutions, because I am always aware of the ca-

83. veats surrounding an idea, and the different possibilities that
could be adopted, and am not focused on a visual model of
what to do. It does also have some prosaic consequences like
making it harder to orient myself in open country (whereas a
town, rich in shop names, street signs and so on is relatively
easy).
SDAM, meanwhile, is manifest in the way I experience the
past and future. When I think about past events in my life I am
aware that I was there, and frequently aware of details that
are personal, and not told to me by others. I may also be aware
of where people were sitting relative to me, and what colour
their clothes were. I saw the film Vertigo a few days ago, and
still have a sense of the rich redness of the restaurant from the
scene where James Stewart first sees Kim Novak. I have a
feeling that I can form and store some sort of unseen quasi-
spatial memories. What I don't have is the experience that
people describe of feeling that they are back in another time
and re-living it. This doesn't mean that I am untroubled by the
past or future, quite the opposite, it just means that the past

84. really is “another country” to which I have no passport. Like A
E Housman I can feel nostalgia for “the land of lost content …
the
happy highways where I went, and cannot come again”, but
unlike
him I don't “see [the land] shining plain”. It is much harder for
me
to assess the difference SDAM has made to me compared to
aphantasia. My guess is that its most important effects have
been to do with forward planning, which uses the prospective
memory. This is certainly the potentially affected area that I
feel the greatest actual need to improve. The philosopher
Galen Strawson (Strawson, 2004) has made the interesting
suggestion that some (perhaps most?) people have a strong
sense of themselves as having a continuous “story-arc”, and
has labelled them as “Diachronic”, in contrast with his own
“Episodic” outlook, where “the way I am now is profoundly
sha-
ped by my past, but it is only the present shaping consequences
of the
past that matter, not the past as such”, very reminiscent of the

85. Markovian concept in mathematics, where the next state of a
system is only determined by its present one. Importantly, he
notes that this is not identical with what he calls the Narrative
or non-Narrative experience of life, and isn't straightforwardly
coupled to whether one has episodic memories or not (as
apparently he does).
I was already 35, and working as a physicist in Cambridge,
when a half-page newspaper column (Bywater, 1997) first
tipped me off about the real meaning of phrases like “the
mind's eye” and “bringing back memories”, which up until
then I can only assume I took to be figures of speech. The
author, Michael Bywater, immediately grabbed my attention
by asserting that time is an illusion but you can never tell what's
going to do the trick. You don't believe me? Ask any theoretical
physicist or better still, an actual physicist if you can find one
… but
he won't tell you what the trick is because he doesn't know … If
he did
[…] he'd open a business: time rolled back while you wait”. He
went
on, brilliantly and concisely, to describe the “state of mind
where the past is not just a collection of memories but a
sanctuary,

86. and you strive to get back there and you can't”, and talk about
“the
process of Rolling Time Back. You choose a memory, focus on
it, let
the rest of the mind go blank, and wait”. I suddenly realized
that
not only did I not “see” pictures in my mind, but that I also had
no “Proustian” recall of the type he described: whether
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pictures, sound, or any other sensory memory. He captured
the quality of episodic memory that William James referred to:
“Memory requires more than mere dating of a fact in the past. It
must be dated in my past” (Greenberg & Knowlton, 2014).
When
coupled with projection into one's own future this is the ability
that Tulving was one of the first to call “mental time travel”,
seeing it as a quintessentially human ability (Falk, 2008).
What intrigues me most about his piece in retrospect is
that there was nothing exclusively visual about his descrip-
tion, it is as much aural, sensual and textural, as for example

87. his recall of “the special weight of girls in autumn … when they
lean
against you as you walk along”. Nonetheless I was made aware
simultaneously of my total absence of waking visual imagery,
and of the kind of memory that much later I was to learn is
called “episodic”, in a context that immediately linked these
two deficits.
Both for my own personal peace of mind, and because I am
a scientist, I was very curious about these deficits, but for the
next ten years or so much of what I had to go on was the
testimony of my friends, family and colleagues. I fortunately
felt able to talk quite freely to them, but none were aphantasic,
and all reported that they possessed episodic memory. These
sources were supplemented with what I could glean from the
web and occasional glimmers of insight from excellent but
still somewhat tangential books like (Kosslyn, 1994) and
(Schacter, 1996). Because of this scarcity of information,
coming upon Galton (1880) and James (1890) within a year or

88. two was the key next step for me, and as a physicist I was
naturally intrigued by Galton's conclusion that “scientific men
as a class have feeble powers of visual representation”,
although I
was finding even from my own first enquiries that this was not
the case among the present-day scientists I spoke to, and a
careful re-analysis of his own data does not really substanti-
ate his view (Brewer & Schommer-Aikins, 2006). Importantly,
Galton's work explicitly linked imagery and memory, and was
thus of relevance to both my deficits, though I tended not to
distinguish them initially and simply thought of them as a
missing “visual memory”. Unfortunately I didn't start keeping
a diary, but I think my overwhelming reaction was to wonder
why I had never encountered this aspect of his work, espe-
cially because as a physicist I was aware of many of his pio-
neering contributions to statistics, although I understood that
his role as a founder of eugenics has made him an unavoid-
ably problematic figure.
I could have stopped my enquiry right there in the late 19th
century, but the natural immediate question was what had

89. happened to this field of research since then, and whether a
fuller scientific explanation of my situation now existed. I
soon encountered the account by Thomas (1997) of the
“iconophobia” of J B Watson and Knight-Dunlap, and reports
of how, after early progress like the Columbia University PhD
thesis by Betts (1909), the scientific study of mental …
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Letter to the Editor
Lives without imagery e Congenital aphantasia
Adam Zeman a,*, Michaela Dewar b and Sergio Della Sala c
a University of Exeter Medical School, College House, St
Luke's Campus, Exeter, UK
b Department of Psychology, School of Life Sciences, Heriot-
Watt University, Edinburgh, UK
c Human Cognitive Neuroscience, University of Edinburgh,
Edinburgh, UK
a r t i c l e i n f o
Article history:
Received 3 March 2015

90. Reviewed 5 May 2015
Revised 18 May 2015
Accepted 20 May 2015
Published online 3 June 2015
* Corresponding author. University of Exeter
E-mail addresses: [email protected]
http://dx.doi.org/10.1016/j.cortex.2015.05.019
0010-9452/© 2015 Elsevier Ltd. All rights rese
agnosia and imagery loss, and ii) ‘imagery generation’ deficits
selectively disabling imagery (Farah, 1984).
count of ‘blind imagination’, with the important difference
1. Introduction
Visual imagery is, for most of us, a conspicuous ingredient of
everyday experience, playing a prominent role in memory,
daydreaming and creativity. Galton, who pioneered the
quantitative study of visual imagery with his famous ‘break-
fast-table survey’, reported a wide variation in its subjective
vividness (Galton, 1880). Indeed, some participants described
‘no power of visualising’. This phenomenon has received little
attention since, though Faw reported that 2.1e2.7% of 2,500
participants ‘claim no visual imagination’ (Faw, 2009).

91. The experience of voluntary imagery is associated with
activity in fronto-parietal ‘executive’ systems and in posterior
brain regions which together enable us to generate images on
the basis of our stored knowledge of appearances
(Bartolomeo, 2008). The relative contributions of lower and
higher order visual regions to the experience of visual imagery
are debated (Bartolomeo, 2008). Clinical reports suggest the
existence of two major types of neurogenic visual imagery
impairment: i) visual memory disorders, causing both visual
Medical School, College
(A. Zeman), [email protected]
rved.
In 2010 we reported a particularly ‘pure’ case of imagery
generation disorder, in a 65 year old man who became unable
to summon images to the mind's eye after coronary angio-
plasty (Zeman et al., 2010). Following a popular description of
our paper (Zimmer, 2010), we were contacted by over twenty
individuals who recognised themselves in the article's ac-
that their imagery impairment had been lifelong. Here we
describe the features of their condition, elicited by a ques-
tionnaire, and suggest a name e aphantasia e for this poorly

92. recognised phenomenon.
2. Results
21 individuals contacted us because of their lifelong reduction
of visual imagery. We explored the features of their condition
with a questionnaire devised for the purpose and the Vivid-
ness of Visual Imagery Questionnaire (VVIQ) (Marks, 1973)
(see
Supplementary Material for further details). Participants
typically became aware of their condition in their teens or
twenties when, through conversation or reading, they realised
that most people who ‘saw things in the mind's eye’, unlike
our participants, enjoyed a quasi-visual experience. 19/21
were male. 5/21 reported affected relatives. 10/21 told us that
all modalities of imagery were affected. Our participants rat-
ing of imagery vividness was significantly lower than that of
121 controls (p < .001, Mann Whitney U test e see Fig. 1).
Despite their substantial (9/21) or complete (12/21) deficit in
voluntary visual imagery, as judged by the VVIQ, the majority
of participants described involuntary imagery. This could
occur during wakefulness, usually in the form of ‘flashes’ (10/

93. House, St Luke's Campus, Exeter EX1 2LU, UK.
.ac.uk (M. Dewar), [email protected] (S. Della Sala).
mailto:[email protected]
mailto:[email protected]
mailto:[email protected]
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Fig. 1 e Distribution of Vividness of Visual Imagery
Questionnaire (VVIQ) scores in participants with
aphantasia and control participants (VVIQ range extends
from 16, lowest imagery score to 80, highest imagery
score).
c o r t e x 7 3 ( 2 0 1 5 ) 3 7 8 e3 8 0 379
21) and/or during dreams (17/21). Within a group of partici-
pants who reported no imagery while completing the VVIQ,
10/11 reported involuntary imagery during wakefulness and/
or dreams, confirming a significant dissociation between
voluntary and involuntary imagery (p < .01, McNemar Test).
Participants described a varied but modest effect on mood and

94. relationships. 14/21 participants reported difficulties with
autobiographical memory. The same number identified
compensatory strengths in verbal, mathematical and logical
domains. Their successful performance in a task that would
normally elicit imagery e ‘count how many windows there are
in your house or apartment’ e was achieved by drawing on
what participants described as ‘knowledge’, ‘memory’ and
‘subvisual’ models.
3. Discussion
4antası́a, phantasia, is the classical Greek term for imagina-
tion, defined by Aristotle as the ‘faculty/power by which a
phantasma [image or mental representation] is presented to
us’ (Aristotle, translated Hamlyn, 1968). We propose the use of
the term ‘aphantasia’ to refer to a condition of reduced or
absent voluntary imagery. Terms used previously in related
contexts include ‘defective revisualisation’ (Botez, Olivier,
Vezina, Botez, & Kaufman, 1985) and ‘visual irreminiscence’
(Nielsen, 1946).

95. Sceptics could claim that aphantasia is itself a mere fan-
tasy: describing our inner lives is difficult and undoubtedly
liable to error (Hurlburt & Schwitzgebel, 2007). We suspect,
however, that aphantasia will prove to be a variant of neuro-
psychological functioning akin to synaesthesia (Barnett &
Newell, 2008) and to congenital prosopagnosia (Gruter,
Gruter, Bell, & Carbon, 2009). Indeed, aphantasia may have
some specific relationship to these disorders, as congenital
prosopagnosia is associated with unusually low (Gruter et al.,
2009), and synaesthesia with unusually high (Barnett &
Newell, 2008), VVIQ scores.
The participants described here were self-selected and
some of our findings, such as the male predominance, may
reflect the readership of a science magazine like Discover.
There is a need, therefore, for further study in a more repre-
sentative sample. The existence of lifelong ‘aphantasia’ raises
numerous additional questions. How commonly does
congenital aphantasia occur? Existing data suggest a fre-
quency of around 2% but there is no fully reported large scale

96. study. The evidence of familial occurrence should be investi-
gated further. Does congenital aphantasia have objective
neuropsychological associations? Correlations between im-
agery vividness and cognitive functioning have been elusive in
the past, but recently developed measures of autobiographical
memory (Levine, Svoboda, Hay, Winocur, & Moscovitch,
2002),
imaginative thinking and ‘visual-object intelligence’
(Blazhenkova & Kozhevnikov, 2010) open up new avenues for
exploration. Personality and mood may also be relevant vari-
ables. Are there subtypes of congenital aphantasia? The de-
scriptions given by our participants suggest that in some cases
visual memory is preserved even if visual imagery is absent,
while others may rely entirely on non-visual representations
in memory tasks; the relationship between aphantasia and
congenital prosopagnosia also deserves further study. If, as
we hypothesise, the absence or reduction of visual imagery
has neural correlates, can we discover these? We are opti-

97. mistic that modern structural and functional brain imaging
may help to answer questions about the nature of visual im-
agery that were first posed in ancient Greece and first quan-
tified at Sir Francis Galton's breakfast table over a hundred
years ago.
Supplementary data
Supplementary data related to this article can be found at
http://dx.doi.org/10.1016/j.cortex.2015.05.019.
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http://dx.doi.org/10.1016/j.cortex.2015.05.019
http://dx.doi.org/10.1016/j.cortex.2015.05.019Lives without
imagery – Congenital aphantasia1. Introduction2. Results3.

101. DiscussionAppendix A. Supplementary dataReferences
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Discussion forum
Reflections on aphantasia
Adam Zeman a,*, Michaela Dewar b and Sergio Della Sala c
a University of Exeter Medical School, College House, St
Luke's Campus, Exeter, UK
b Psychology, School of Life Sciences, Heriot-Watt University,
Edinburgh, UK
c Human Cognitive Neuroscience, University of Edinburgh,
Edinburgh, UK
We recently coined the term ‘aphantasia’ to describe the
experience of people who lack a ‘mind's eye’ (Zeman, Dewar,
& Della Sala, 2015), highlighting the features of lifelong
aphantasia in a group of 21 individuals who had contacted us
after reading a popular account of a related paper (Zeman
et al., 2010) by Carl Zimmer in the science magazine
Discover (Zimmer, 2010). Several consistent characteristics
emerged: most participants discovered in their ‘teens or

102. twenties, to their surprise, that when others spoke of ‘visu-
alising’ items in their absence, these others had a genuinely
‘visual’ experience; the majority of our participants, in fact,
had some experience of visual imagery from visual dreams or
from involuntary ‘flashes’ of imagery occurring, for example,
at sleep onset: their aphantasia thus involved a deficiency of
voluntary imagery rather than a total absence; in general, the
emotional consequences of discovering their aphantasia were
modest; most participants regarded their autobiographical
memory as poor.
In their commentary ‘Refusing to imagine? On the possibility of
psychogenic aphantasia’, de Vito and Bartolomeo draw attention
to the possibility that in some cases at least, aphantasia may
have a ‘psychological’ or ‘functional’ basis. The title of the
commentary, ‘refusing to imagine’, suggests that the psy-
chological process might involve an element of choice. We
agree with these authors that ‘psychological’ factors such as
mood can influence imagery, and that a full assessment of

103. aphantasia should include a ‘psychopathological examina-
tion’. We also agree that almost every clinical phenomenon
exists in a ‘factitious’ form. However, their commentary pro-
vokes additional thoughts.
De Vito and Bartolomeo allude to the traditional distinction
between ‘functional’ and ‘organic’, referring specifically to the
* Corresponding author. University of Exeter Medical School,
College
E-mail addresses: [email protected] (A. Zeman),
[email protected]
http://dx.doi.org/10.1016/j.cortex.2015.08.015
0010-9452/© 2015 Elsevier Ltd. All rights reserved.
debate concerning the aetiology of retrograde amnesia (for
contrasting views see De Renzi, 2002 and Kopelman, 2002).
There is undoubtedly a useful working distinction between
irreversible, structural causes of neuropsychological symp-
toms and reversible, functional ones. However the familiar
distinction between the ‘functional’ and ‘organic’ is a dubious
one: we are all organisms, and our functions and dysfunctions
are therefore, necessarily, organic. The neurologist Kinnier
Wilson stated this point in especially uncompromising terms
in a famous passage in his textbook: the ‘antithesis between

104. ‘organic’ and ‘functional’ disease states … lingers at the
bedside and in medical literature, though it is transparently
false and has been abandoned long since by all contemplative
minds' (Kinnier Wilson, 1940). We suspect that De Vito and
Bartolomeo would agree. We labour the point here because it
suggests the interesting hypothesis e echoed in discussions of
retrograde amnesia (Lucchelli & Spinnler, 2002), as de Vito and
Bartolomeo point out e that aphantasia will involve some
common pathways in the brain whether it is due to due to
reversible, ‘psychological’ or irreversible, ‘structural’ causes.
De Vito and Bartolomeo draw attention to controversy
surrounding Charcot's famous case of aphantasia, the case of
Monsieur X (Charcot, 1889). In the absence of brain imaging
data or post mortem findings, the aetiology of Monsieur X's
loss of imagery will never be known with certainty. It is true,
as de Vito and Bartolomeo point out, that Monsieur X had been
under unusual stress prior to the onset of his symptoms, and
had fallen prey to uncharacteristic anxiety and low mood.
These features could set the scene for ‘psychogenic aphan-

105. tasia’. Several aspects of this complex case, however, point to
a neurological basis for his aphantasia, including the abrupt
onset of Monsieur X's symptoms, their association with
House, St Luke's Campus, Exeter EX1 2LU, UK.
.ac.uk (M. Dewar), [email protected] (S. Della Sala).
mailto:[email protected]
mailto:[email protected]
mailto:[email protected]
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.08.015&domain=pdf
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c o r t e x 7 4 ( 2 0 1 6 ) 3 3 6 e3 3 7 337
prosopagnosia and some disturbance of colour vision. More-
over his symptoms persisted despite an apparently successful
readjustment to his new mental circumstances: ‘He realised,
moreover, little by little, that he could by other means, by
invoking the aid of other forms of memory, continue to suc-
cessfully direct his business affairs. And thus, at the present
time, he has become reconciled to the new situation … ’
(Charcot, 1889; page 154). While Zago et al. (Zago et al., 2011)

106. argue for a psychological reading of Monsieur X's case, Young
and van de Wal (Young & van de Wal, 1996), contrary to de
Vito
and Bartolomeo's account, underline the remarkable degree to
which Charcot's lecture anticipates the themes of subsequent
descriptions of aphantasia. They do note with surprise, how-
ever, that Charcot failed even to consider the possibility of a
psychological explanation in this case, given his interest in
hysteria.
The data we presented from our series of 21 participants
were derived from a questionnaire survey and lacked the
systematic, psychological detail we hope to include in a future
face-to-face study. However, several considerations suggest
that these individuals' aphantasia is unlikely to have a pri-
marily ‘psychopathological’ explanation. All participants
described a characteristic of their mental lives that was, so far
as they knew, lifelong. Aphantasia was a stable state rather
than a variable trait. Few described any major emotional
concomitants. Most were leading fulfilling personal and pro-
fessional lives. We are impressed by one further association:

107. impoverishment of imagery appears to be common in
congenital prosopagnosia (Gruter, Gruter, Bell, & Carbon,
2009). While our 21 participants did not specifically report
problems with face recognition, it is likely that there is some
overlap between aphantasia and congenital prosopagnosia, a
condition few would regard as predominantly ‘psychogenic’.
The vividness of self-reported visual imagery varies widely
among healthy individuals (McKelvie, 1995). In addition to this
normal variation, the existing literature points to a range of
pathological and pharmacological factors that can influence
vividness. It can be dimmed or abolished by brain injury
(Farah, 1984). Depression, anxiety and depersonalisation can
have similar effects (Sierra, 2009), whereas imagery is
heightened in psychopathologies such as post-traumatic
stress disorder and by hallucinogens like mescaline and LSD
(Carhart-Harris et al., 2012). In all these cases the precision of
self-report is open to question, but the vagaries of introspec-
tion are unlikely to account entirely for the wide range of

108. variation described both within and between individuals.
Thus, in essence, we fully agree with de Vito and Bartolo-
meo that psychological and psychiatric factors should be
taken into account in the assessment of a person complaining
of aphantasia. These factors will themselves have neural
correlates. We are doubtful that psychopathology plays a
major role among people reporting lifelong aphantasia.
History sometimes repeats itself: a further account by Carl
Zimmer of our recent paper, in the New York Times (Zimmer,
2015), has prompted around a thousand individuals with
aphantasia to make contact with us, attesting to the popular
interest and relative obscurity of this fascinating variation of
human experience. We look forward to future explorations of
the experiential, neuropsychological, neuropsychiatric and
neural features of aphantasia.
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June 23rd, D3.
Received 10 August 2015
Reviewed 14 August 2015
Revised 14 August 2015
Accepted 14 August 2015

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http://dx.doi.org/10.1016/j.cortex.2015.08.015
http://dx.doi.org/10.1016/j.cortex.2015.08.015Reflections on
aphantasiaReferences
www.sciencedirect.com
c o r t e x 7 4 ( 2 0 1 6 ) 3 3 4 e3 3 5
Available online at
ScienceDirect
Journal homepage: www.elsevier.com/locate/cortex
Commentary
Refusing to imagine? On the possibility of
psychogenic aphantasia. A commentary on Zeman

113. et al. (2015)
Stefania de Vito a,b,* and Paolo Bartolomeo a,b
a INSERM U 1127, CNRS UMR 7225, Sorbonne Universit�es,
and Universit�e Pierre et Marie Curie-Paris 6, UMR S 1127,
Institut du Cerveau et de la Moelle �epini�ere (ICM), Paris,
France
b Department of Psychology, Catholic University, Milan, Italy
Our ability of “seeing” mental images in the absence of
appropriate sensory input has always raised great interest
not only in science, but also in philosophy (Sartre, 1940), art
and literature (de Vito, 2012). Remarkably, however, some
people claim not to experience visual mental images at all.
Although the existence of these cases has been known to
science for well over 100 years (Galton, 1880, 1883), the phe-
nomenon has been oddly ignored and a systematic research
is still lacking. Zeman, Dewar, and Della Sala (2015) provide
important insights into several aspects of the lifelong
inability to mentally visualize absent objects and label this
condition “aphantasia”, a convenient term that may help
focusing research on the phenomenon. The authors report
on otherwise healthy people. However, this condition has

114. been also observed in different populations of patients. Since
Charcot (see Bartolomeo, 2008, for an English summary;
Charcot & Bernard, 1883) neurologists have described cases
of acquired inability to form visual mental images (review in
Bartolomeo, 2002). However, it is worth noticing that in some
of these cases, including the seminal Charcot case (Charcot &
Bernard, 1883), an “abrupt and isolated” loss of visual imag-
ery has been interpreted by some as having a psychogenic,
rather than organic, origin (Zago et al., 2011). When consid-
ering evidence such as that reported by Zeman et al. (2015), it
is important to keep this possibility in mind. Indeed, the case
of imagery loss could engender an “organic/functional”
debate analogous to the one that has revolved around
* Corresponding author. Centre de Recherche de l'Institut du
Cerveau
Bâtiment ICM, 47-83 Boulevard de l'Hôpital, Paris 75013,
France.
E-mail address: [email protected] (S. de Vito).
http://dx.doi.org/10.1016/j.cortex.2015.06.013
0010-9452/© 2015 Elsevier Ltd. All rights reserved.
retrograde amnesia (e.g., De Renzi, Lucchelli, Muggia, &

115. Spinnler, 1997).
Published in 1883 in Le Progr�es M�edical, the case of
Monsieur
X was presented as a sudden loss of the ability to construct
mental images linked to a hypothetical circumscribed cerebral
lesion and represents a classical citation in studies discussing
the loss of visual imagery (e.g., Zeman et al., 2010). Although
no evidence was available about the etiology or locus of the
lesion (there was no post-mortem examination), left temporal
damage sparing the occipital cortex might be hypothesized,
given the described reading problems in the absence of
elementary visual impairment (Bartolomeo, 2008). This hy-
pothesis is consistent with neuropsychological and neuro-
imaging studies revealing that large networks of brain areas
are engaged during visual mental imagery, probably reflecting
top-down influences from frontal and parietal regions to the
temporal lobe (e.g., Mechelli, Price, Friston, & Ishai, 2004).
However, it is also important to consider that, at the onset of
his imagery disorder, Monsieur X experienced something akin

116. to mental alienation. Things around him appeared strange
and new and he became anxious. As Monsieur X wrote to
Charcot, “I observed a drastic change in my existence that
obviously mirrored a remarkable change in my personality.
Before I used to be emotional, enthusiastic with a prolific
imagination; today I am calm, cold and I lost my imagination”
(p. 570, own transl.). The Portuguese neurologist Ant�onio de
Sousa Magalh~aes e Lemos (1906) observed a similar case of
et de la Moelle �epini�ere, Inserm U 1127, Hôpital de la
Salpêtri�ere,
mailto:[email protected]
http://crossmark.crossref.org/dialog/?doi=10.1016/j.cortex.2015
.06.013&domain=pdf
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www.elsevier.com/locate/cortex
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http://dx.doi.org/10.1016/j.cortex.2015.06.013
c o r t e x 7 4 ( 2 0 1 6 ) 3 3 4 e3 3 5 335
visual imagery loss in a woman with an experience of recur-
ring hysterical crises, other than depressive and anxious
symptomatology. However, once again, an organic root (i.e.,

117. damage to the connectional networks between memories and
“the spared center of mental images”, p. 27, own transl.) was
hypothesized for the disease. Cotard was the first to empha-
size the existence of an intimate association between
depressive/anxious symptomatology and visual imagery loss:
“We cannot prevent ourselves from thinking that the relation”
between these two phenomena “goes beyond the fortuitous
coincidence” (Cotard, 1884, p. 292, own transl.). His two pa-
tients, M.P… and M.***, with severe anxious and depressive
symptoms, became totally incapable to shape mental images,
and M.P… also developed the Cotard delusion, and believed he
was dead. According to Cotard (1884), the delusion of non-
existence of the self was likely to be determined by a misin-
terpretation of the mental imagery loss, since this symptom is
common in patients with chronic anxiety. Since then, a
number of similar cases was observed where the loss of visual
imagery accompanied depersonalization and derealisation,
which are dissociative disorders often associated with anxiety

118. and depression (e.g., Deny & Camus, 1905; Dugas, 1898). In
1898, the French philosopher Ludovic Dugas coined the term
“depersonalization” to describe “a state in which there is the
feeling or sensation that thoughts and acts elude the self and
become strange; there is an alienation of personality” (Dugas
& Moutier, 1911, p. 12). Dugas (1898) reported the case of pa-
tient M., whose awareness of having become incapable to
mentally visualize an absent person marked the onset of his
chronic depersonalization. In 1960, the Italian psychiatrist
Gian Carlo Reda described four patients who had experienced
a loss of visual mental imagery in the context of a complex
medical history involving anxiety attacks, depressive states,
and, above all, depersonalization and derealisation (“I only
have words in my mind, I cannot see anything”, Reda, 1960, p.
109). Simeon et al. (2000) also described the disturbance in
mental imagery as one of the factors subsuming depersonal-
ization/derealisation. Thus, it may be suggested the existence
of two categories of patients (i.e., organic and functional) who

119. may experience impaired visual imagery, with different
characteristics (e.g., Zago et al., 2011, highlighted that the
emphatic complain of the loss of visual imagery is recurrent in
functional patients, but rare in neurological patients). A third
category may also be possible, where organic and functional
factors overlap. In light of such considerations, a critical
reexamination of Monsieur X's psychopathological symp-
tomatology provided Zago et al. (2011) with clues as to the
possible alternative functional root of his deficit. In fact,
Monsieur X presented some of the symptoms identified in
functional aphantasia (e.g., anxiety, depression, depersonal-
ization with derealisation). Moreover, Freud, who personally
examined Monsieur X, suspected a neurosis and Young and
van de Wal (1996) suggested a hysterical origin.
Therefore, an impairment of the “mind's eye” may be
linked to heterogeneous variables, which need to be properly
kept into account in future investigations. Cases of “aphan-
tasia” should receive not only neuropsychological and neu-
roimagery assessments, but also psychopathological

120. examination.
Acknowledgments
We are grateful to Stefano Zago for very helpful discussion
and for providing us with several historical articles.
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Received 27 May 2015
Reviewed 1 June 2015
Revised 2 June 2015
Accepted 3 June 2015
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