This document discusses sense perception and how we make sense of the external world through our senses. It outlines the five main senses of sight, smell, taste, touch, and hearing, while noting scientists disagree on the total number, which may be between 9 and 21. When we lose senses, as in Helen Keller's case of losing sight and hearing, we rely more on our remaining senses. The document contrasts empiricism, which believes knowledge comes from the senses, with rationalism, which believes knowledge comes from reason. It also discusses how illusions reveal the limitations of direct realism and show perception is subject to interpretation within the brain. Cultural and personal contexts influence how we perceive and interpret the world. While senses provide information, perception

1. Sense Perception

2. What is Sense Perception?
• Perception is generally defined as:
– ‘The awareness of external stimuli through the use of
our senses’
(this is how we make sense of the Universe around us)
• We are generally aware of 5 [Aristotelian] senses:
– Touch
– Hearing
– Sight
– Smell
– Taste
Scientists say we have more – but disagree on the total (somewhere between 9 and 21)
http://edrontheoryofknowledge.blogspot.mx/2015/04/super-senses.html
http://edrontheoryofknowledge.blogspot.mx/2015/04/how-many-senses-do-we-have.html

3. What happens if we lose senses?
• Helen Keller lost her senses of
hearing and sight when she
was 19 months old
• She maintained she would
rather regain her hearing than
her sight as hearing
(language?) is what connects
us to other people
https://www.youtube.com/watch?v=aTJv0DoIgY8
http://edrontheoryofknowledge.blogspot.mx/2011/09/helen-keller.html

4. Empiricism and Rationalism
• Empiricism is the philosophical theory that knowledge
comes only (or mostly) from the senses – this is a
posteriori knowledge
• Rationalism is the competing theory that knowledge
comes only (or mostly) from reason (from the mind) –
this is called a priori knowledge
• These are the two ideas that underpin epistemology
(theory of knowledge). But perhaps we can agree for
now that knowledge can be both a posteriori and a
priori

5. Direct Realism
• The idea that objects just exist ‘out there’ and they have specific
properties that are just the way our senses allow us to perceive
them i.e. if grass appears green to us it is because the property of
‘greenness’ is inherent within it
• However we already know that different people perceive things
differently
• Also science tells us that the greenness of grass is not due to an
internal property, but due to the externality of how light reflects
from it
• The greenness does not exist in the grass, but rather it’s the
interpretation within our brains
• If (as direct realism tells us) our senses tell us exactly what is in
front of us, it shouldn’t be possible to fool our senses

6. Illusions

7. Illusions
This is a Necker cube. Depending on your point of
focus you should be able to change its perspective

8. Illusions
"Spinning Dancer" by Nobuyuki
Kayahara - Procreo Flash Design
Laboratory. Licensed under CC BY-
SA 3.0 via Wikimedia Commons -
http://commons.wikimedia.org/
wiki/File:Spinning_Dancer.gif#/m
edia/File:Spinning_Dancer.gif
You may see the dancer spinning clockwise or anticlockwise. You may even be able to
Change your focus to it appears to suddenly spin in the opposite direction

9. Illusions
• Auditory illusions show that your sense of
hearing can be tricked as easily as your sense
of sight
– misheard lyrics
• If the theory of direct realism was correct then
magicians would be out of business

10. Illusions
• Illusions occur either due to:
– Tricking our sense itself
– Tricking our interpretation
• Interpretative illusions consist of:
– Changing context
– Substituting figure and background
– Visual grouping
– Expectation

11. Changing Context
We make contextual calculations all the time, for example when we consider
perspective in order to determine the size of an object

12. Substituting Figure and
Background
The brain tries to concentrate on
what it believes is in the
foreground. But you can switch
the part of an image which you
perceive as the foreground

13. Visual Grouping
We constantly try to make sense of what we see by grouping objects to see
familiar pattern. This may result in pareidolia

14. Visual Grouping - Pareidolia
Pareidolia occurs when random shapes are given significance
where none really exists. Perhaps most familiar is the appearance
of faces (often with religious meaning) in everyday objects
http://edrontheoryofknowledge.blogspot.mx
/2013/05/jesus-appears-in-pot-of-
marmite.html

15. Expectation
Our brains can’t process all of the information they receive all the time
therefore we unconsciously pick out parts of this information and make it
into a whole

16. Interpreting Our Perception
• Interpretation of what we perceive occurs in the brain
• We couldn’t possibly interpret all of the information our
senses gather every second
• Therefore interpretation must be selective
• What it selects depends to some degree on what is
important for survival
• The brain filters out what is not important – e.g. until you
think about it you are unaware of the ticking of the clock on
the wall
• On the other hand, the brain will give importance to other
things – e.g. a sudden movement in the corner of your eye
• However, what you perceive also depends to some degree
on your background and interests (i.e. cultural context)

17. Cultural Context
• How would the following things be observed
in the cultural context of the following people:
– A child dying in poverty as seen by a doctor, an
economist, a social worker, the child’s father
– A sunset as seen by a religious person, a physicist,
an artist, a farmer
– A tree as seen by a biologist, a logger, an
environmentalist, an indigenous person from the
forest
Your education, interests, influence of friends, family etc. all contribute to how you
interpret your own sense perception therefore everybody’s perception even of very
simple things can be very different

18. Perception and Belief
• Natural Science:
– In the nineteenth century it was widely accepted
that there must by an as yet unobserved planet to
explain the eccentric orbit of Mercury
– It was so widely believed that some astronomers
actually reported observing this new planet
through their telescopes (they even named it…
Vulcan)
http://edrontheoryofknowledge.blogspot.mx/2014/08/planet-vulcan.html

19. Perception and Belief
• Human Sciences
– In 1987, in the county of Cleveland, England, 121 cases of
suspected child sexual abuse were diagnosed by paediatricians
Marietta Higgs and Geoffrey Wyatt
– All of the children were subsequently removed from their
families (57 families in all)
– After a number of trials, the cases involving 96 of the 121
children were dismissed by the courts, and they were returned
to their parents.
– It appeared that some of the children may have experienced
‘false memories’ which developed during therapy. It seemed
that in believing the suggestions of their doctors these children
perceived that they had been abused (even developing
memories of it occurring) when, in fact, they hadn’t been
abused
http://edrontheoryofknowledge.blogspot.mx/2013/03/child-abuse-and-false-memories.html

20. Perception and Belief
• Art
– In the eighteenth and
nineteenth centuries horses
were routinely drawn
galloping with outstretched
legs and all four hooves off
the ground at once (it just
seemed intuitive that this
was the way they moved)
– The use of photography (by
Eadweard Muybridge in
1872) proved in that this
depiction was completely
unnatural

21. Eyewitness Testimony
• Our courtrooms put a lot of emphasis on the importance and
reliability of eye-witness statements
• However, if sense-perception (not to mention memory) is so
fallible, should we really trust eye-witnesses
The men on the left and right were picked out of police line-ups for rapes and
robberies committed by the man in the middle

22. Trusting Your Perception
• You can never achieve certainty through sense perception,
but how much trust can you put in what you perceive?
• You may end up with false information through:
– Misinterpretation of what you perceive
– Failure to notice something
– Misremembering (or even creating ‘false memories’)
• You can put more trust in perception via:
– Confirmation by another sense
– Coherence
– Testimony from another person

23. Confirmation
• The idea that if two or more senses seem to
agree independently, then you can be
reasonably certain that what you are
experiencing is reality
• e.g. If something looks like an apple, feels like
an apple and tastes like an apple, you can be
reasonable sure that it is an apple
Don’t confuse ‘sense confirmation’ with ‘confirmation bias’

24. Coherence
• The idea that if something appears to you to be
outside of your normal realm of sense perception
then the chances are that you are mistaken
• However everybody’s experience of what is
acceptably normal is different. Also, by definition
faith in something does not require justification
and may therefore be accepted without
questioning

25. Testimony From Another Person
• This is a case of confirmation not through your
own senses, but through those of somebody
else
• We have already seen that eyewitness
testimony may be untrustworthy, but at least
can be used to build confidence in your own
interpretation

26. Visual Agnosia
• This came to the public’s attention in the book ‘The Man Who
Mistook his Wife for a Hat’ by Oliver Sacks
• It is a condition where people with brain damage are unable to
recognise visual objects
• This is due to a breakage between the parts of the brain that deal
with vision and interpretation of the image – it is not due to
problems with language or memory
• People with agnosia tend to rely on senses other than vision to
confirm the identity of objects. They are also obviously reliant on
the testimony of other people
https://www.youtube.com/watch?v=ze8VVtBgK7A
https://www.youtube.com/watch?v=T1qnPxwalhw