1. APRIL 2015
Can Thoughts Direct our Attention? The
effects of experimentally induced
preoccupation on attentional bias
Ingrid Fadelli
Psychology BSc
School of Social Sciences
City University, London
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Acknowledgements
I would like to thank Professor Emmanuel Pothos for his attentive supervision
throughout the present study, and Mariona Serra for assisting me in its realisation.
An additional special thanks goes to my family and friends, who motivated me and
supported me whilst carrying out this investigation.
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Abstract
Substance abuse and particular patterns of eating behaviour have been increasingly
associated with attentional biases for substance or food related stimuli (e.g. Cox &
Klinger, 2004; Calitri et al., 2010). Some theories suggest these biases are displayed
towards stimuli that are more ‘salient’ for affected individuals, perhaps due to a goal-
directed concern associated with them (Klinger, 1975,1977, 1987; Klinger & Cox,
2004). The current study attempted to experimentally elicit preoccupation for an
assumedly neutral semantic category in a sample of 56 Psychology undergraduates,
consequently measuring their attentional bias for its associated stimuli. Participants
completed two tasks; one involved planning a goal-directed activity, and the other
organising word stimuli. Several mixed factor ANOVA analyses compared
participants’ RTs to Stroop stimuli related to the task that should have elicited
preoccupation with those related to the organising words task. These analyses found
no significant Stroop theme x preoccupation task theme interaction effect, suggesting
the experimental manipulation either did not elicit preoccupation in participants, or
this concern was not sufficient to cause an interference effect for stimuli related to the
task that was designed to generate it.
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Introduction
Attention is one amongst the most widely investigated topics within the field of
Cognitive Psychology. It is generally defined as a cognitive process that enables
human beings to filter out environmental events (MacLeod & MacDonald, 2000).
Under particular circumstances, though, it can manifest itself through the formation of
attentional distractions or ‘attentional bias’ for emotionally salient environmental
stimuli. Attentional bias has been often found to play a dominant role in maintaining
types of psychopathology, such as anxiety (e.g. Williams, Mathews & MacLeod,
1996). More recently, research explored associations between attentional effects and
addiction, particularly to alcohol and tobacco smoking (e.g. Waters & Feverabend,
2000; Cox & Klinger, 2004). Psychology research has been increasingly highlighting
the presence of attentional biases for stimuli related to substances of interest in
individuals with substance use disorders, and for food related stimuli in those
displaying particular patterns of eating behaviour. A suggested explanation for this
observed phenomenon is that substance/food related stimuli are a cause for concern
and hence become more salient for affected individuals, resulting in an attentional
bias towards them (Cox, Fadardi & Pothos, 2006).
The current study aims at investigating the suggested link between an individual’s
preoccupation with a particular topic, in addiction being the substance of abuse, and
observed attentional bias for stimuli related to it. A large body of literature explored
the plausible dynamics of addiction-related attentional bias, and those relevant to our
study will be outlined in detail, before introducing the current investigation further.
Measuring attentional bias
Firstly, when referring to attentional bias, it is important to understand operational
methods that have been developed to measure it, particularly the one relevant to the
current study. Several different paradigms have been adopted as measures of
attentional bias, both in psychopathological and addiction-related studies. Amongst
these are the dot-probe task, the flicker paradigm and the dual-task for addiction
(Hogarth, Dickinson & Duka, 2003; Jones et al., 2003; Waters & Green, 2003). One
of the most commonly employed measures of attentional bias is an adaptation of the
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Stroop task (Stroop, 1935). Studies employing both dot-probe tasks and Stroop tasks
as measures of attentional bias, reported different findings between the two,
suggesting they might be capturing different aspects of information processing (e.g.
Johansson, Ghaderi & Anderson, 2004; Calitri et al., 2010). Stroop paradigms,
nevertheless, appear to overall be more successful at uncovering positive findings of
attentional bias, particularly in relation to addiction and eating behaviour (Calitri et
al., 2010; Cox et al., 2002). Therefore, the current investigation measured
participants’ attentional bias using a version of the emotional Stroop task. Before
outlining how the Stroop task was integrated in the study, nevertheless, it is important
to outline theory and evidence related to it as a measurement tool.
The Stroop task is a paradigm investigating interference during serial verbal reactions.
In its classic version, participants are presented with colour words printed in different
colours of ink, which could either be matching or in opposition. Participants are
instructed to state the colour of the ink in which each word is printed ignoring it’s
meaning entirely. In the classic version of the paradigm, Stroop interference, or
‘Stroop effect’, occurs when participants’ reaction times (RTs) are greater for
incompatible colour words than for words matching their ink colour (Stroop, 1935).
Classic Stroop tasks have been widely used to investigate attentional processes, and
have been found to demonstrate adequate test-retest reliability (Conner, Franzen &
Sharp, 1988).
Emotional Stroop tasks are an extended version of the classic test, using emotionally
salient word stimuli in the experimental condition instead of colour related words.
Interference effects in these versions of the Stroop paradigm suggest an attentional
bias for presented stimuli (Williams et al., 1996). Stroop tasks with word stimuli of an
emotional nature have been used in the study of cognitive processes associated with
psychopathologies, such as depression and anxiety (Williams et al., 1996). Stroop
paradigms employing word stimuli related to substances of abuse or food, on the
other hand, have been implemented in investigations of attentional bias in addicted
individuals, as well as those displaying particular patterns of eating behaviour (Cox,
Fadardi, Pothos, 2006).
Many cognitive theories attempted an explanation of the dynamics underlying what is
referred to as ‘Stroop effect’, in the classic version of the task as well as in emotional
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and addiction-related ones. As the current investigation will employ a modified
version of the emotional Stroop paradigm, the classic version of the test and its
dynamics are not immediately relevant, and theories hereby reviewed will primarily
relate to the former. When it comes to applying theories attempting an explanation of
the classic ‘Stroop effect’ to emotional and addiction-related versions of the test, most
do not appear relevant, as in the latter perceptual and semantic dimensions of stimuli
are not in direct contraposition to each other (Cox, Fadardi & Pothos, 2006).
Nevertheless, observations of brain activity while performing both addiction-based
and classic Stroop tests reported greater activation of the ACC in both circumstances
(MacLeod & MacDonald, 2000). This led some to suggest that some processes
involved in the execution of classic Stroop tasks might be common to emotional and
addiction-based ones (Pardo et al., 1990).
For instance, both classic and emotional versions of the Stroop paradigm involve
presenting participants with stimuli that can be encoded in two distinct ways,
perceptually and by reading, hence processing a word’s semantic meaning (MacLeod,
1991). Some researchers suggested that processing word meaning is more automatic
than processing ink colour, as reading is a better-learned dimension (MacLeod &
Dunbar, 1988). Emotional Stroop tests, nevertheless, do not employ colour related
word stimuli, and an observed interference effect would hence not be due to a word
being in semantic contraposition with its ink colour, but to other underlying dynamics
(Cox, Fadardi & Pothos, 2006).
A series of meta-analyses conducted on addiction Stroop tasks results, enabled
researchers to draw some important conclusions. Firstly, tests designed to elicit
addiction related bias appeared to result in greater Stroop ESs than non-substance
related manipulations (Cox, Farardi & Pothos, 2006). Moreover, as the difference in
extent to which a substance was used or desired by participants in control and
experimental groups increased, Stroop ESs also appeared to increase (Cox, Farardi &
Pothos, 2006).
Research on Stroop task performance often suggested interference effects to be
influenced by several procedural and methodological factors. The selection of both
Stroop stimuli and procedure for the current study was largely informed by prior
evidence, suggesting output differences when employing different methodological
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strategies. Firstly, theory suggests that choice of word stimuli should be carried out
equating various linguistic dimensions, such as number of words, letters and syllables,
across salient and neutral categories (Cox, Fadardi & Pothos, 2006). A study also
found the frequency at which stimulus words appear in the relevant language to also
affect the extent of resulting interference effects, with higher frequency words
producing greater RTs (Burt, 2002). In addition to this, evidence suggested the more
words in the same Stroop task trial are semantically related, the slower the RTs and
hence greater the interference effect, assumedly due to an increase in inter-trial
priming of related concepts (Cox, Brown & Rowlands, 2003).
In terms of procedural choices, the current study presented Stroop stimuli in blocks,
as blocked presentations have been found to result in greater interference effects
(MacLeod, 1991). This could be due to response strategies being developed across a
block of trials with constant response demand, or to inter-trial semantic priming
(MacLeod, 1991; Warren, 1972). In addition to this, carry over effects might occur
when response to one stimulus facilitates answering the immediately presented one,
especially when employing random presentation (Waters, Sayette & Wertz, 2003). In
addiction Stroop tasks, interference induced by blocked presentations has been
attributed to ruminative thinking in the presence of salient stimuli, resulting in longer
reading time (Waters, Sayette & Wertz, 2003).
Another methodological aspect of the current study that has been informed by prior
research evidence is the way in which stimuli were presented to participants, whether
on cards or on a computer. This has been found to affect the extent of observed
interference effects, card versions of Stroop tasks leading to larger interference
effects, despite computerized advantages in terms of precise data collection (Klindt,
Bierman & Brosschot, 1996). Similarly, interference effects have been found to be
greater when participants are instructed to respond orally than manually, finding
attributed to the similar linguistic nature of vocal responses and word processing
(MacLeod, 1991). On the other hand, practice after repeated trials has been suggested
to reduce interference effects, although the evidence for this is not entirely consistent
(MacLeod, 1998; Fadardi, 2003).
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Overall, meta-analyses of addiction-related Stroop task results, found selection of
particular stimuli, the format of the test and the means by which it was presented to
participants, to be important factors in enabling the detection of attentional bias (Cox,
Fadardi & Pothos, 2006). Moreover, due to evidence suggesting a broad variability in
outcomes of emotional Stroop tasks, results should be cautiously interpreted (Field &
Cox, 2008).
Attentional bias, addiction and overeating
Before discussing cognitive theories relevant to the current investigation, it is
important to understand the reasons prompting this study more thoroughly, and hence
its plausible application. Several studies within the field of cognitive psychology
indicated that attentional biases play a role in corresponding behaviour.
A study of attentional bias for food-related stimuli in relation to body weight found it
to be a poor predictor of current BMI (Pothos, Tapper & Calitri, 2009). Nonetheless, a
further exploration reported that attentional bias to food cues, assessed using a food-
related Stoop task, successfully predicted a change in BMI over a 1 year period, after
controlling for effects of weight related variables such as physical activity, stress,
restrained eating and emotional eating (Calitri et al., 2010). Food-related Stroop tasks
revealed that greater RTs while processing unhealthy food word stimuli were
significant predictors of BMI increase the following year, whereas greater RTs in
response to healthy food word cues predicted the opposite trend (Calitri et al., 2010).
In another study, restrained eaters displayed a higher interference effect on a food-
related Stroop task than non-restrained eaters (Francis, Stewart & Hounsell, 1997).
Similar investigations have also been conducted amongst individuals engaging in
addictive behaviours, especially towards alcohol and tobacco smoking. A wide
amount of evidence has been collected suggesting associations between implicit
cognitions and alcohol abuse, and addicted individuals have been found to display
particular implicit memories, retrieval processes and affective reactions triggered by
alcohol-related stimuli (Wiers et al., 2002). The plausibility of implicit cognitions has
been highlighted in other addiction study reviews, which dismissed links between
reflective decision-making and addiction, proposing that influential cognitions are
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spontaneously and automatically activated, at critical decision points (Stacy & Wiers,
2010).
For instance, a study carried out at an alcohol addiction centre, found that patients
with RTs to alcohol-related Stroop tasks that increased during a four-week treatment
were significantly more likely to relapse, three months later, than those who
maintained stable RTs throughout treatment (Cox et al., 2002). Another study
reported a greater reduction in post-study frequency of drinking behaviour in
excessive drinkers with a lower attentional bias for alcohol-related stimuli, compared
to those who exhibited a high attentional bias for these stimuli (Cox, Pothos & Hosier,
2007). Similarly, interference effects in both alcohol-related and emotional Stroop
tasks were found to be greater in individuals with tendencies to abuse alcohol than in
non-abusers (Stormark et al., 2000).
Despite the considerable amount of evidence collected supporting the presence of
attentional bias for alcohol-related stimuli in alcohol abusers, another study found no
significant difference between alcohol-dependent and control participants in extent of
addiction Stroop interference (Bauer & Cox, 1998). Predicted group differences could
have, nonetheless, been masked by relatively low alcohol dependency of the
assumedly alcohol-dependent experimental group (Bauer & Cox, 1998). Other
studies, in fact, found positive correlations between the magnitude of Stroop
interference and indices of alcohol dependence, which could reflect the respective
extent of subjective alcohol-related concern (e.g. Ryan, 2002).
An investigation of performance in smoking-related Stroop tasks amongst regular
smokers, found that interference effects significantly varied according to whether
participants were told they could smoke soon, could not smoke for at least one hour or
had a 50% chance of being able to smoke (Wertz & Sayette, 2001a). When they were
told they would be able to smoke soon, greater Stroop interferences were collected
and greater subjective craving manifested, suggesting a further link between
attentional bias and goal-related expectancy, particularly in the context of tobacco
smoking behaviours (Wertz & Sayette, 2001a).
Overall, the above studies suggested the association between attentional biases and
addictive/unhealthy eating behaviours. A further understanding of the specific
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dynamics underlying these biases, like the one the current study aims to achieve,
might thus be informative for the development of treatments attempting a
modification of such behaviours.
Cognitive psychology theories of attentional bias associated with substance use and
particular eating behaviours
After various investigations repeatedly confirmed the presence of attentional biases
for substance or food related stimuli in individuals who engage in addictive and
particular eating behaviours, various theories attempted an explanation of this
phenomenon and the implicit processes possibly underlying it. This section will
outline some of the main theoretical accounts for attentional biases associated with
addictive behaviour, ultimately highlighting the ones most relevant to the current
investigation.
One of the questions raised by attentional bias researchers is what assumedly
increases ‘salient’ stimuli’s priority over ‘neutral’ ones. Emotional salience attributed
to stimuli has been often primarily related to behaviourist views of conditioning and
positive reinforcement, suggesting that behaviour could momentarily reduce negative
affect, or positively appeal to one’s reward system (Cox, Fadardi, Pothos, 2006).
According to this view, emotional reactions associated with unconditioned and
conditioned stimuli would result from wired-in goals, and these would impact on
cognitive functioning (Cox, Fadardi, Pothos, 2006). In addition to this, attentional
biases in substance abusers have been linked to memory for addiction-related
concepts, implying a preferential memory for substance use-related information (Cox,
Fadardi, Pothos, 2006). Delayed RTs to colour naming in addiction-related Stroop
tasks could, therefore, be associated with selective momentary retrieval of stimuli-
associated memories (Cox, Fadardi, Pothos, 2006).
Another notion that has been developed around addictive behaviour and related biases
is implementation intentions. These are defined as intentions that automatically
activate a particular behaviour when a related stimulus is presented, assumingly
represented by ‘if-then’ conditionals in an individual’s memory (Cox Fadardi, Pothos,
2006). Memory processes related to addictive behaviour or unhealthy patterns of
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eating behaviour would thus be modulated by context, including subjective
motivational state (Krank et al., 2005).
The role of conditioning has also been emphasised by cognitive psychology models,
attempting a detailed account of observed attentional effects in individuals with
addiction or particular patterns of eating behaviour. One of these proposes that
classical conditioning causes substance-related stimuli to elicit expectancy for
substance availability in substance users, suggesting that subjective craving and
attentional bias arise as a result of substance anticipation (Field & Cox, 2008).
Conditioning is hereby referred to as a learning process occurring after repeated
parings of individual effects of the perceived availability of a substance and
concurrent environmental cues, leading to the development of conditioned responses
to substance-related cues (Field & Cox, 2008). According to this model, attentional
bias and craving arise as a consequence of this conditioning process, and have a
mutually excitatory relationship that induces addicted individuals to self-
administration of the relevant substance (Field & Cox, 2008). Research evidence also
suggested that subjective craving for substances of abuse is experienced by users both
when a substance-related cue raises their expectancy for substance availability, and
when substance-related stimuli are presented in a context in which proximal use is
assumed (Hogarth & Duka, 2006; Wertz & Sayette, 2001b; Wilson, Sayette & Fiez,
2004).
A further suggestion, the most relevant to the current investigation, is that interference
might not necessarily result from history of substance use, but might be simply due to
the relatedness of stimuli to current concerns (Williams et al., 1996). For instance, a
study found both patients and staff working at an addiction centre to display slower
RTs, assumed to reflect interference effects, on addiction Stroop tasks (Cox et al.,
2002). A possible explanation for this, is that concern for a particular topic might
result in a higher threshold for topic-related stimuli, this process being modulated by
one’s neuromodulatory system, influencing neural flow of competing information
(Cox, Fadardi & Pothos, 2006). This would result in concern-related stimuli building
stronger connections in neural pathways, potentially reflecting observed attentional
biases towards them (Cox, Fadardi, Pothos, 2006). Theoretical emphasis on the role
of topic-related concern in observations of attentional biases is relevant to our
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investigation, attempting to elicit preoccupation for a particular topic and
consequently assessing attentional bias for stimuli related to it.
Another model attempting an explanation of attentional biases associated with
addiction is the Incentive-sensitization theory, proposing that substance-related cues
acquire motivational properties that alter the way in which users perceive them
(Robinson & Berridge, 1993). This theory suggests that repeated administration of
substance is what produced dopaminergic responses that gradually increase and
become more sensitized every time it is used (Robinson & Berridge, 1993). This is
assumed to lead to craving the substance, that acquires incentive-motivational
properties inclined towards attaining it, and consequently grabs addicted individuals’
attention more readily (Robinson & Berridge, 1993). This account acknowledges the
relationship between subjective craving and attentional bias, suggesting they are
emotional and cognitive outputs of an individual’s sensitized dopaminergic system
that is motivated to perform substance-seeking behaviour (Robinson & Berridge,
1993). This theory is also partially relevant to the current study, as the task employed
to elicit preoccupation for a particular topic consists of performing a goal-oriented
topic related task, assumed to elicit more responses relevant to motivation, and ideally
result in topic-related stimuli becoming more salient, prompting attentional bias
towards them.
Cognitive models exploring the links between addictive behaviour and attentional
biases for abused substances, supported by a considerable amount of research
evidence, would have several addiction treatment implications. For instance, they
might signify the efficacy of CBT as a therapeutic strategy, as well as tackling
attentional bias as a useful way to relieve subjective craving (Wietkiewicz & Marlatt,
2004; de Jong, Kindt & Roefs, 2006). Our study focuses on attempting an
investigation of the specific relationship between concern for a particular topic and a
display of attentional biases for stimuli related to this topic. Should a significant
relationship between the two be observed in a sample of normal population, this
would suggest that a topic-specific goal-directed preoccupation, might be at least
partially underlying displays of attentional bias for stimuli related to it.
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Preoccupation and attentional bias
In addition to theories advocating the essential role of conditioning, attentional bias
has been interpreted by some theories, outlined above, as being linked to a goal-
oriented concern with a particular topic. A study on volunteers who spent 24 weeks
on a diet meant to induce semi-starvation supported this notion, by revealing an
increase in subjects’ preoccupation with food, that continued until after its
completion, suggesting the possible role of fantasy and motivation in shifting
individuals’ attention to particular stimuli (Brozek et al., 1951; Brozek, Guetzkow &
Balwin, 1951). The current investigation aims at collecting further evidence related to
this assumption, the main notions behind which are now to be more thoroughly
explained.
A theoretical perspective specifically emphasizing the idea underpinning the current
study is the theory of current concerns, suggesting that individuals’ lives tend to be
organized around the pursuit of desired goals. Concern related to the fulfilment of a
particular motivational goal, would hence endure and cause an observed biased
processing of goal-related stimuli (Klinger, 1975; 1977; 1987). Individuals might,
therefore, develop a hypersensitivity to motivationally salient stimuli, potentially
reflected in attentional bias towards them (Klinger, 1977). This suggestion links in
with incentive-sensitization theories and other cognitive models outlined above, in
highlighting the importance of motivation for attentional bias observations, thus
assuming it is a phenomenon of a goal-directed nature (Robinson & Berridge, 1993).
In the context of addictive behaviours, substance users would display automatic
cognitive processes linked to the goal of substance-use (Klinger & Cox, 2004). These
automatic processes would be expected to gradually decay once the goal pursuit is
terminated, which is consistent with prior evidence (Mogg et al., 1995). Research also
confirms that concern-relatedness of stimuli can predict attentional bias regardless of
an individual’s cognitive functioning (Fadardi & Cox, 2006).
Finally, the theory of current concerns suggests that commitment to a particular goal
of interest results in subsequent concern with this goal, that could potentially be
inhibited but not entirely eradicated (Klinger, 1975; 1977; 1987). This concern would
assumedly be reflected in biases towards goal related-stimuli (Klinger & Cox, 2004).
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The current study
After reviewing theoretical perspectives that propose a link between attentional biases
and current concerns, the current study focuses primarily on exploring this notion
further. As aforementioned, some researchers in cognitive psychology suggested
attentional bias might be closely linked with one’s current concerns and a particular
motivational state towards achieving a desired goal (e.g. Klinger, 1975; Fadardi &
Cox, 2004). An individual’s preoccupation with a particular goal, therefore, might be
reflected in delayed Stroop RTs to goal-related stimuli. These stimuli, when
presented, are thus assumed to be differently processed compared to neutral ones.
(e.g. Brozek et al., 1951; Fadardi & Cox, 2004; Klinger, 1977). Motivational
preoccupation for a substance is hence suggested to be source of attentional bias for
substance-related cues, in addicted individuals as well as in others displaying similar
biases. The aim of this study was to investigate the relationship between motivational
concern (or preoccupation) and attentional bias, within an experimental setting.
This experiment was carried out on a normal population, in order to test the above
cognitive assumption in general and not only specifically in terms of substance abuse,
eating behaviour or psychopathology. Firstly, we attempted to elicit preoccupation for
a particular topic, by participants completing a task involving planning a goal-related
activity and being interrupted halfway, but told they could complete it later. Ideally,
planning a project or task around a particular topic, would trigger participants’
motivational thinking, and after being interrupted, topic-related information would be
processed differently than stimuli that were not related to the planning task previously
assigned. By interrupting participants, and suggesting they would be offered more
time to complete the task later on, we also attempted to prompt concern to an even
greater extent, as they would expect to eventually have to revisit the goal-related
activity, which never actually happened. Attentional bias towards word stimuli, both
related and unrelated to the planning task, would then be subsequently assessed using
a study-specific emotional Stroop task.
In order to avoid possible confounding factors related to the absence of a control
condition, another task was introduced, before the Stroop task, assumed not to elicit
preoccupation. This control task instructed participants to organise words without
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semantically processing their meaning, and not planning any goal-directed activity.
RTs to stating the colour of stimuli semantically related to this control task were,
subsequently, statistically compared to those related to the task that should have
triggered participants’ preoccupation. Statistically significant greater Stroop
interference effects for stimuli related to the planning/goal-oriented task, than to the
organising information task, would suggest cues related to the former became more
salient for participants, possibly due to motivational properties acquired following
task completion. This would be aligned with the assumptions outlined by the theory
of current concerns, proposing motivational states towards a particular goal’s
attainment increases preoccupation for goal-related information, causing different
automatic attentional responses to goal-related cues (Klinger, 1975,1977, 1987;
Klinger & Cox, 2004).
The main hypothesis of the current study’s outcome was the following:
A planning/goal-directed task will result in significantly greater Stroop RTs to word
stimuli semantically related to it, than a task instructing participants to organise words
without encoding their semantic meaning.
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Method
Participants
The sample consisted of 56 first year Psychology Undergraduate students at City
University, 6 males and 50 females. The age range was 18-25 with a mean age of
18.88. No exclusion criteria were implemented and participants voluntarily signed up
for the study on Sona systems, website used by City University researchers for sample
recruitment. Candidates were assigned 30 course credits for their participation.
Design
The experiment followed a 2 (Stroop task theme: Gardening vs. First aid) x 2
(Preoccupation task theme: Gardening vs. First aid) x 2 (Preoccupation task order:
preoccupation task 1st vs. preoccupation 2nd) mixed factorial design. The first variable
was within participants and the last two between participants.
Stroop task theme, the only variable with repeated measures, consisted of the
semantic category to which a block of Stroop word stimuli belonged to, and its levels
were gardening vs. first aid.
Preoccupation task theme was the semantic theme of the presenting information task
assigned to a particular participant, depending on allocated booklet version, and its
levels were gardening vs. first aid. The second between participants variable was
preoccupation task order, the order in which the presenting information task, assumed
to elicit preoccupation, was handed out during the experiment. Its levels were
preoccupation task 1st vs. preoccupation task 2nd.
Amongst some of the variables that could have confounded the outcome of the
experiment, are the words’ possibly different levels of familiarity, personal relevance
and positive/negative attribution for individual participants. Similarly, individual
category biases might have been present at baseline, such as differences in how
participants related the two particular themes employed in the study (gardening or
first aid). As the study was conducted on first year undergraduate students, the
possibility of them not taking the experiment seriously and not engaging in the tasks
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properly was also considered. In order to reduce the impact of this factor, completed
tasks were later rated from 0-3 on the quality of the work, to run further analyses on
the most valid results.
Stimulus material
Four different versions of experimental booklets were used throughout the
experiment, differing in order and theme of the first two parts of the experiment. 14
copies of each version were printed out and each participant was randomly assigned
one of these. Each booklet contained an information sheet, a demographics sheet, a
consent form, a debrief form and three separate tasks: a presenting information task,
an organizing information task and a Stroop task (containing four separate blocks of
Stroop stimuli within it). The first two parts of the experiment varied in each booklet
version in order and theme of the presenting information task, assumed to induce
preoccupation in participants. Theme and order of the organising information task
varied accordingly (e.g. if theme of the preoccupation task was gardening, the theme
of organising information task was first aid; if the former was presented first, the
latter was second etc.). The theme and order combinations for each of the booklets
used are outlined in Table 1.
Table 1: Preoccupation Task theme and order for different booklet versions.
Booklet
Version
Permutation
1 Theme of Preoccupation task: Gardening
Order: Preoccupation task 1st
2 Theme of Preoccupation task: First Aid
Order: Preoccupation task 1st
3 Theme of Preoccupation task: First Aid
Order: Preoccupation task 2nd
4 Theme of Preoccupation task: Gardening
Order: Preoccupation task 2nd
18. 18
Presenting Information Task (or Preoccupation task):
The presenting information task consisted of planning an imaginary project (related to
either gardening or first aid) for which participants had to take notes and brainstorm
ideas. Gardening and first-aid were selected as experimental task topics for two main
reasons. Firstly, they were assumed to be neutral semantic categories. Secondly, they
were considered suitable for planning a category relevant goal-oriented project,
objective of the presenting information task.
The word stimuli that would later be used in one of the Stroop tasks were included in
the instructions for this task. The stimulus material used can be found in Appendix A.
Organizing information task:
In the organizing information task, words that would later be included in one of the
experimental Stroop tasks, once more related to gardening or first aid, were to be
organized in three ways: alphabetically, by number of letters and by number of
syllables, all by ascending order. Specific stimulus material used for this task can be
found in Appendix B.
Stroop Task:
Four separate blocks of Stroop stimuli were printed out, two of which contained
words used in the previous two tasks. One of these contained words semantically
related to gardening and the other to first aid. The other two blocks of Stroop stimuli
contained numeric words, considered to be neutral within the experimental context.
These four distinct blocks of Stroop stimuli were handed out one at a time, in
randomised order, during the final part of the experiment, which was the same
regardless of one’s allocated booklet version. All stimulus material used for this task
can be found in Appendix C. A stopwatch was used to time total RTs taken to state the
colours of all words on each block.
Word stimuli used in experimental Stroop task conditions, for both gardening and
first-aid, were matched to respective control words in terms of number of letters and
syllables, in order to avoid differences in these two dimensions from impacting on the
outcome. These control words were used in the two respective Stroop control
conditions. All experimental word stimuli used, and their respective control match
can be found in Appendix D.
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After data had been collected, a criterion was established to rate the individual quality
of the work produced by participants in the organising and presenting information
tasks. These ratings were assumed to partially reflect the effort placed by participants
in task completion and were then used in statistical analysis to explore whether results
varied when quality of the work was higher. Ratings ranged between 0-3 points.
Criteria for presenting information ratings:
1 point: if more than 5 words from word stimuli list were used.
1 point: if participants wrote more than 5 sentences.
1 point: for quality and relevance of participant’s notes (subjective rating).
Criteria for organising information ratings:
1 point: if task was complete and all words organised
1 point: if organisation of all words was correct
1 point: if at least 2/3 of organising information instructions were fulfilled
Procedure
The experiment took place on an individual basis in a sound proof experimental lab.
Participants were asked to read the experiment information sheet and sign a consent
form. A demographics sheet was also provided, in which participants were asked to
note down their gender, age and nationality. Once both experimenter and participant
signed the consent form, a randomly allocated version of the experimental booklet
was handed out, one task at a time.
Firstly, according to what booklet version had been assigned to them, participants
were either given the organising information or presenting information task. The
content of these tasks was either related to first aid or gardening, also according to the
allocated booklet version. All participants were asked to read instructions carefully,
and were encouraged to ask any questions should they need clarification on how to
proceed. Once ready to begin, candidates had 5 minutes to complete the task. Once
20. 20
time was over, the experimenter handed out the second task. Once again, this varied
in instructions and thematic content according to the booklet version assigned to the
specific participant. Participants were once more given time to read the instructions
carefully and encouraged to ask if they required any further explanation. Once they
were ready to start, they had 5 minutes to work on this second task.
Regardless of whether it had been given to them first or second, once the assigned 5
minutes for the presenting information task were over, participants were told they
would have more time to come back to it later on.
Finally, the third part of the booklet was handed out, containing the Stroop task within
all booklet versions. Once ready to start, the experimenter placed the first block of
Stroop stimuli on the desk, and used a stopwatch to measure how long the participant
took to state the ink colours of all words presented in it, out loud. This procedure was
repeated for all four blocks of Stroop stimuli, which were handed out to all
participants singularly and in a random order. Once all Stroop tasks had been
completed and all RTs recorded, the experimenter thanked participants for their
collaboration and provided them with an explanatory debrief sheet.
21. 21
Results
The Mean and Standard Deviation values of all participants’ Stroop experimental
Reaction Times minus control Reaction Times, for both gardening and first aid
preoccupation tasks, are reported in Table 1. Descriptive statistics revealed two slight
outliers in the data, both within block of Stroop stimuli related to first aid. These were
not considered crucial enough to be removed for further analysis.
Table 1. Mean and Standard Deviation values for gardening and first aid
preoccupation tasks
Experimental – Control RT Gardening Experimental – Control RT
Fist Aid
Mean SD Mean SD
Gardening -132.25 348.89 -71.28 335.63
First Aid -112.04 364.27 -94.62 325.44
A Mixed Factor ANOVA was initially ran on all data collected, including nationality
(British vs Not British) and experimenter (Experimenter 1 vs Experimenter 2) as
between participants’ variables, together with the variables of Stroop theme
(Gardening vs. First aid), preoccupation task theme (Gardening vs. First aid), and
preoccupation task order (1st vs. 2nd). Gender was not included, as males within the
experimental sample were very few.
This ANOVA analysis revealed no significant Stroop Theme x Preoccupation Task
Theme interaction, F(1,40)=2.22, p=.15, and no significant Stroop Theme x
Preoccupation Task Order interaction, F(1,40)=.02, p= .89. Nonetheless, the results
revealed a significant three-way Stroop task theme x preoccupation task theme x
preoccupation task order interaction, F(1,40)=4.27, p=.05.
Due to the lack of significance of effects relevant to the study’s investigation,
nationality and experimenter were removed from the ANOVA analysis. The effects of
22. 22
Stroop Theme, Preoccupation Task Theme and Preoccupation Task Order on
Reaction Times during experimental Stroop tasks minus Reaction Times during
control Stroop tasks were examined more closely, using a 2 (Gardening vs First Aid)
x 2 (Gardening vs First Aid) x 2 (Preoccuation task First vs Preoccupation task
Second) Mixed Design ANOVA with repeated measures on the first factor.
This mixed ANOVA analysis on all data collected revealed no significant Stroop
Theme X Preoccupation Task Theme interaction, F(1,52) = .25, p =.62, and no
significant Stroop Theme X preoccupation task order interaction, F(1,52) = 3.01, p
=.09. Moreover, the Stroop task theme x preoccupation task theme x preoccupation
task order interaction was also not significant, F(1,52)= 1.17, p= .29.
The Pearson’s correlation between participants’ performance in presenting
information task and organising information task, scored 0-3 following the previously
outlined criteria, was low, r = .21, n = 56, p = .12. Therefore, two further ANOVA
analyses were consequently conducted, after eliminating participants with
performance ratings lower than 2 in the presenting information task. Initially,
nationality (British vs Not British) and experimenter (Experimenter 1 vs.
Experimenter 2) were once again included in the ANOVA as between participants’
variables, in addition to Stroop theme, preoccupation task theme and preoccupation
task order. This analysis revealed a significant three-way Stroop task theme x
preoccupation task theme x preoccupation task order interaction, F (1,28)=5.35, p=
.03. In terms of the interactions most relevant to the investigation, Stroop theme x
Preoccupation task theme interaction was found not to be significant, F(1,28)=.58,
p=.45, as was the Stroop theme x Preoccupation task order interaction, F(1,28)=.51,
p= .48.
Having found no significant interactions supporting the study’s hypothesis, a further
ANOVA analysis was carried out without including nationality and experimenter
variables, yet maintaining the data selection criteria of performance ratings greater
than 1 in the presenting information task. This analysis, however, still revealed no
significant Stroop theme x preoccupation task theme interaction, F(1,39) = .75, p=.39.
An error bar chart exploring the Stroop theme x preoccupation task theme interaction,
revealed a non-significant trend in the opposite direction compared to predictions
(Graph 1).
23. 23
Graph 1- Error bar chart for Preoccupation Task Theme and Stroop Theme
Variables.
Contrary to the previous analyses, this mixed ANOVA revealed a significant Stroop
Theme x Preoccupation Task Order interaction, F(1,39)=4.27, p=.05. An error bar
chart exploring this interaction effect suggested two main trends. When the
preoccupation task was given first to participants, reaction times to gardening Stroop
stimuli appeared to be greater. On the other hand, when it was given second, reaction
times resulted significantly greater for the first aid relevant block of Stroop stimuli
(Graph 2).
24. 24
Graph 2- Error bar chart for Preoccupation Task Order and Stroop Theme Variables
A final attempt exploring the data was made by extending the data exclusion criteria
of performance ratings lower than 2 to both presenting and organising information
tasks, these assumed to be the overall most valid results. This led to the inclusion of
36 cases in the analysis; descriptive statistics of these are reported in Table 2.
Table 2. Mean and Standard Deviation values, for gardening and first aid
preoccupation tasks, after excluding ratings <2 in both Presenting Information and
Organising information tasks.
Experimental – Control RT Gardening Experimental – Control RT
Fist Aid
Mean SD Mean SD
Gardening -224.92 390.41 -144.85 359.01
First Aid -119.00 310.96 -141.17 397.55
25. 25
Once again, two subsequent Mixed-ANOVA analyses were conducted on this data,
the first one including experimenter and nationality as factors and the second only the
three variables relevant to the investigation. The first of these analyses revealed a
three-way Stroop theme x preoccupation theme x preoccupation order interaction,
F(1,21)=4.90, p=.04.
The second mixed ANOVA ran on data excluding ratings lower than 2 on both
organising and presenting information tasks included only variables relevant to the
specific investigation, respectively Stroop theme, preoccupation theme and
preoccupation task order, with repeated measures on the first factor. Despite the data
reduction, this analysis still revealed no significant interactions, with Stroop theme x
preoccupation theme interaction F(1,32)=.18,p=.67, Stroop theme x preoccupation
order interaction F(1,32)=2.03, p=.16 and Stroop theme x preoccupation theme x
preoccupation order interaction F(1,32)=1.41, p=.24.
26. 26
Discussion
Overall, the experiment did not produce the expected results. The data collected was
bizarre and not aligned with predictions, and descriptive statistics, both including all
data and only the assumedly most valid results, revealed high SD values and negative
means. This suggests a peculiar pattern of results and an observed opposite
relationship between experimental and control Stroop task performance, than the one
necessary to infer an interference effect for experimental stimuli. RTs to control
blocks of Stroop stimuli appeared to be overall greater than RTs to respective
experimental blocks of Stroop stimuli, leading to negative means of differences
between them.
A three-way Stroop task theme x preoccupation task theme x preoccupation task order
interaction effect was revealed by ANOVA analyses including experimenter and
nationality as variables, on all data as well as with the two data selection criteria
implemented. These three-way interactions are difficult to interpret in the context of
this study, due to its modest sample size and the considerable variability within it.
The interaction between Stroop theme x preoccupation task theme, which was
assessing expected results, was non-significant under all data circumstances,
prompting further mixed factor ANOVA analyses without experimenter and
nationality included as variables. These analyses on all data, nonetheless, still
revealed no significant Stroop Theme X Preoccupation Task Theme interaction,
F(1,52) = .25, p =.62, and no significant Stroop Theme X preoccupation task order
interaction, F(1,52) = 3.01, p =.09.
Consequently, performance ratings lower than 2 in the presenting information task
were excluded, due to the low correlation between presenting information ratings and
organising information ratings, r=.21, n=56, p=.12. Results, nevertheless, still
revealed no significant Stroop Theme x Preoccupation Task theme interaction,
F(1,39) = .75, p=.39, contrary to predictions. An error bar chart exploring the Stroop
Theme x Preoccupation task theme interaction actually revealed a non-significant
trend in the opposite direction, suggesting the experimental manipulation was
nowhere near successful.
27. 27
On the contrary, this ANOVA uncovered a significant Stroop Theme x Preoccupation
Task Order interaction, F(1,39)=4.27, p=.05. An error bar chart exploring this effect
revealed two main trends, greater gardening Stroop RTs when the preoccupation task
was given first to participants, and greater first aid Stroop RTs when the
preoccupation task was handed out second. This was a curious effect, observed only
when the data exclusion criterion of presenting information task ratings lower than 2
was implemented. This effect was unusual and not too big, so it might have simply
been caused by a combination of confounding variables.
In further absence of relevant significant results, a final data exclusion criterion was
established to attempt further investigation. Excluding both organising information
and presenting information task ratings lower than two, was assumed to signify
inclusion of most valid results only. These were participants who scored 2 or higher
on both presenting and organising information tasks, and therefore executed tasks
properly, placing a considerable amount of effort in both of them. If the design
successfully elicited preoccupation for the presenting information task over the
organising information task, participants would have arguably performed both tasks
thoroughly for it to be most effective in its intent. Nevertheless, the ANOVA analysis
including the three relevant variables still revealed no significant Stroop theme x
preoccupation theme interaction, F(1,32)=.18,p=.67, or Stroop theme x preoccupation
order interaction, F(1,32)=2.03, p=.16. This confirmed findings in previous ANOVA
analyses, suggesting the design was unsuccessful in eliciting preoccupation in
participants, and in making stimuli from the presenting information task more salient.
Method: flaws and observations
The lack of expected results could be due to many distinct factors, or a combination
of all of them. The study methodology does not appear to have successfully made the
semantic category related to the preoccupation task more ‘salient’ for participants.
This could have been prevented by several components underpinning the
methodology adopted by the study.
Firstly, the presenting information task, which was assumed to elicit preoccupation in
28. 28
participants, might have failed in its intent. Arguably, the choice of first aid and
gardening as semantic categories could have been unsuitable for the study purpose,
and their generally neutral connotations might have actually prevented them from
eliciting participants’ subjective concern. In addition to this, gardening word stimuli
were very field specific, hence many participants were unsure of their meaning and
asked for clarification. Research found frequency at which Stroop word stimuli
appear in the study-relevant language to affect the extent of associated interference, so
this might have also partially impacted on the outcome of the study (Burt, 2002).
Word stimuli related to first aid, on the other hand, might have had more negative
emotional connotations for some participants, being associated with an emergency
situation (e.g. oxygen, blood, etc.).
An extensive amount of variability might have also been present in how individual
participants related to either semantic category, especially in terms of different
selective momentary retrieval of category related memories, which have been
suggested by some researchers to potentially delay RTs to colour naming in
addiction-related Stroop tasks (Cox, Fadardi & Pothos, 2006).
Moreover, the preoccupation task appeared to appeal to common sense when related
to first aid, but allowed for more creative responses when gardening-related. This is
supported by an observation of similar notes, produced by different participants, for
first aid related presenting information tasks, and much greater variability in note-
content when the task was gardening-specific.
Differences in how participants related to the two different task instructions could
have also increased study variability, reflected in the unsuccessful experimental
outcome. Experimenters observed individual differences in how the organising and
presenting information tasks were perceived by participants, some finding the latter
easier and some more difficult. This observation is somewhat supported by the low
correlation between participants’ performance ratings in the presenting information
task and organising information task, r = .21, n = 56, p = .12.
Participants appeared to find organising words easier or more difficult than
completing a creative task using these words, according to their personal disposition.
These differences might have partially affected their perception of word stimuli used
in either one of the two tasks, as well as concern associated with them, ultimately
29. 29
impacting on their Stroop task performance.
The Stroop task methodology employed by the current study was aligned with Stroop
task research findings, reporting greater interference observations using card versions
of Stroop tasks, blocked word stimuli and having participants orally stating stimuli
ink colour (Klindt, Bierman & Brosschot, 1996; MacLeod, 1991; Warren, 1972).
Nevertheless, the investigation still did not lead to expected results. As mentioned in
the introduction, emotional Stroop tasks involve many underlying processes, and can
therefore become very complex measuring tools (Field & Cox, 2008).
Situational variables, such as experimental room size and time of day in which
participants were tested, are not assumed to have substantially affected the outcome of
the experiment. In addition to this, no significant baseline differences were observed
in participants, and randomising booklet version and blocks of Stroop stimuli reduced
these even further.
Conclusions and Implications
The current study attempted to experimentally elicit preoccupation for a particular
semantic category in a normal population sample, in order to explore its effects on
attentional bias towards stimuli related to this category. This bias was assessed using
study-specific emotional Stroop tasks. The experimental manipulation was either
unsuccessful in eliciting preoccupation, or this was not sufficient to result in stimuli
becoming more ‘salient’ for participants, and hence producing longer RTs in related
Stroop tasks.
This investigation was aligned with the theory of current concerns, suggesting that a
motivational or goal-directed preoccupation for a particular topic might result in an
individual’s attentional bias for stimuli related to that topic (Klinger, 1975; 1977;
1987). This has been applied to circumstances where addiction and patterns of eating
behaviour have been associated with attentional biases for substance-related or food-
related stimuli, suggesting that the concern for these particular topics might be what
causes the observed processing bias (Williams et al., 1996). It is important to
30. 30
consider, nonetheless, that the methodology adopted by the current investigation
attempted to elicit preoccupation for neutral categories, not assumed to be of any
particular concern for participants prior study participation. This could prove a very
challenging task, as experimentally elicited concern might never fully equate concern
that is already present, and has been possibly previously established by conditioning
mechanisms, as suggested by other theoretical accounts of addiction-related
processing biases (e.g. Cox, Fadardi, Pothos, 2006). In addition to this, the theory of
current concerns refers to goal-directed preoccupation, and the presenting information
task used in this investigation attempted to elicit this in participants. On the contrary,
it might have actually been more of a common sense exercise, not tangibly increasing
goal-directed concern for a particular semantic category, but merely inducing
participants to brainstorm ideas related to a hypothetical or presently unlikely
situation. If any considerable preoccupation with either gardening or first aid was in
any way elicited in individual participants, this might have thus been due to a pre-
existing subjective goal-directed concern with either of these categories, of which
experimenters were nonetheless unaware. In this case, category associated concern
would have been random and non-systematically spread throughout the sample,
resulting in no statistically significant interference results.
In addition to this, tests designed to elicit addiction-related biases have been
suggested by research to result in greater Stroop effect sizes than non-substance
related ones (Cox, Farardi & Pothos, 2006). The tests adopted by the current
investigation were not substance-relevant, and were also not relevant to any topic of
ascertained emotional significance for recruited participants. The failure to trigger
concern for the experimental topics of gardening and first-aid is, therefore, fairly
understandable, considering that they are supposedly neutral semantic categories.
Suggestions for further research
Overall, the current study suggested experimental attempts to elicit preoccupation for
neutral categories, using analogous methodologies, to be challenging and difficult to
implement. Further research attempting to investigate the relationship between
31. 31
preoccupation and attentional bias, aligned with the theory of current concerns and
other cognitive theoretical accounts for processing biases, should perhaps focus on
established goal-directed concerns for the recruited sample, that equate those of
addiction for addicted individuals. Should further investigations assess a similar
sample of population, for instance, concern for particular topics could be
systematically assessed in participants, other than elicited.
In alternative, experimental categories selected could be more relevant to the specific
sample’s concerns, for instance exams in the case of an undergraduate sample,
employment for an unemployed sample, etc. This might increase the possibility of
these topics being cause for goal-directed concern, and enhance ‘saliency’ of topic-
related stimuli.
A further improvement to the study might be that of employing different experimental
tasks, one of which elicits preoccupation for a particular topic to a significantly
greater extent than the other. A larger sample might also decrease the ‘noise’ within
the manipulation, enhancing any attentional effects. As suggested by attentional bias
researchers, using a variety of attentional bias measures might also lead to different
results, as emotional Stroop tasks are thought to assess various underlying processes
at once (Field & Cox, 2008).
Finally, having participants rate experimental word stimuli in an additional
questionnaire, for instance in terms of familiarity, positivity/negativity and relevance,
could also help determine if any particular pattern of participants’ relationship to
word stimuli enhances expected attentional effects. Assessing aspects of participants’
subjective relationship to experimental word stimuli would also facilitate the process
of controlling for these while carrying out statistical analyses.
32. 32
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Appendix A- Stimulus material for presenting information task
In this study we will explore how people take ideas and present that information.
Imagine you are in charge of a gardening project. For example, imagine that you are
planning to spend the summer with an aging aunt and you promise you will help her
redesign her garden (which is overgrown and has not been looked after for a while).
This is an exciting prospect, but you must first convince your aunt that you have some
good ideas. Please make some notes of what you would do. As this is a complex task,
you will do it in two stages. Make some notes and start an outline now, then you will
do some other tasks, and finally you will return to the task to finish off. To help you
get on, here is a list of relevant words:
Gardening theme version of task:
Spade, Flowers, Decking, Rake, Gnomes, Patio, Lawn, Shed, Weeds, Pruning
First-aid theme version of task:
Bandages, Plasters, Antiseptic, Oxygen, Breathing, Airway, Circulation, Needle,
Recovery, Conscious
There is no right or wrong answer! Please spend about 5 minutes making some notes
regarding the above. After 5 mins, the experimenter will stop you and you will be
asked to continue with the remainder of the booklet. Once you have finished the
booklet you will have 5 more mins to finish off your outline. Please write your notes
in the box below.
38. 38
Appendix B- Stimulus material for organizing information task
In this study we are interested in how easily individuals are able to categorise
information. We would like you to categorise the following 10 words that are
associated with gardening/first-aid:
Gardening theme version of task:
Spade, Flowers, Decking, Rake, Gnomes, Patio, Lawn, Shed, Weeds, Pruning
First-aid theme version of task:
Bandages, Plasters, Antiseptic, Oxygen, Breathing, Airway, Circulation, Needle,
Recovery, Conscious
Please complete the table below and order the above words in the three ways
described at the top of each column of the table.
Alphabetically Number of letters Number of syllables
1 1 1
2 2 2
3 3 3
4 4 4
5 5 5
6 6 6
7 7 7
8 8 8
9 9 9
10 10 10
39. 39
Appendix C- Stimulus material for Stroop task (same in all booklet versions)
i) Instructions:
In this study we are interested in how people process information. The researcher will
present you with four pages containing words written in four different colours (red,
blue, green, yellow). We would like to read the colour of each word aloud to the
researcher. The researcher will time how quickly you complete each page and how
accurately you perform. Please try to be as accurate and quick you can.
Please turn over and wait for the researcher to tell you when to begin.
ii) Stroop task A: Gardening theme experimental condition
Spade
Decking Paving Flowers
Flowers Gnomes Weeding Gnomes
Decking Spade Rake Lawn
Rake Lawn Shed Plants
Gnomes Weeding Plants Decking
Paving Flowers Spade Paving
Lawn Shed Gnomes Rake
Shed Plants Flowers Shed
Weeding Paving Lawn Spade
Plants Rake Decking Weeding
40. 40
iii) Stroop task B: Gardening theme control condition
iii) Stroop task C: First-aid theme experimental condition
Eight Sixteen Thirty Fifteen
Fifteen Twelve Million Twelve
Sixteen Eight Five Four
Five Four Nine Number
Twelve Million Number Sixteen
Thirty Fifteen Eight Thirty
Four Nine Twelve Five
Nine Number Fifteen Nine
Million Thirty Four Eight
Number Five Sixteen Million
Bandages Oxygen Plasters Needle
Needle Airway Antiseptic Airway
Oxygen Bandages Circulation Recovery
Circulation Recovery Breathing Conscious
Airway
Antiseptic Conscious Oxygen
