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Transcript of Exploiting exposure to temptation to support self-control.€¦ · salad). The...
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Exploiting exposure to temptation to support self-control.
Siegfried Dewitte1
To appear in Handbook of Self-Control in Health and
Wellbeing (de Ridder, Adriaanse, & Fujita, 2017)
Abstract
This chapter reviews the pre-exposure effect, the finding that exposing individuals to
tempting foods in a context where they do not consume the foods, reduces their subsequent
free consumption of similar tempting foods. The chapter describes what is known about the
effect and proceeds with discussing the potential underlying mechanisms. The discussion sets
it apart from seemingly similar phenomena ,and identifies a series of open research questions
about the effect and its potential as an element of behavioral change interventions. The
relation between the pre-exposure effect and nudges is discussed from a behavioral
engineering approach.
Keywords: self-control; overconsumption; nudge; behavioral engineering; behavioral change
1 Behavioral Engineering Research Group, Faculty of Economics and Business, KU Leuven
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Exposure to temptation is the leading cause of self-control failure. This truism invites policy
makers, parents, and often even consumers to work either towards a world where
temptations are banned, regulated, or restricted, or towards one where individuals become
masters in resisting the pull of temptations. The compelling nature of this general ‘ban or
resist’ approach may sometimes obscure a third path where the focus is on reducing the pull
of the temptations. In the food domain the most recent approaches indeed identify the ‘ban
or resist’ approach as vulnerable to failure (Appelhans, French, Pagoto, & Sherwood, 2014)
and identify the centrality of changing food preferences as a more robust way forward
(Hawkes et al., 2015). This chapter follows this lead and introduces the pre-exposure effect,
where, quite contrary to a ‘ban or resist approach’, the presence of temptation is leveraged
to reduce its pull.
The chapter proceeds as follows. I will first review the evidence that exposure to temptation
typically increases consumption. I will then address the notable exception, the pre-exposure
effect. I will review the evidence for the effect and its scope, and explore the underlying
mechanisms. In the discussion, I delineate it from similar procedures and propose a research
agenda to further explore the scope of the effect and its potential to be an element of
behavioral interventions. I conclude with a discussion of the relation between the pre-
exposure effect and the nudge concept.
Temptations and self-control failure
The availability of pleasurable stimuli activates the hot system, which motivates the
individual to approach and indulge in the pleasure (Metcalfe & Mischel, 1999). When
indulgence in the pleasure seems to be in conflict with the achievement of some long-term
goal or with some salient principle, these pleasurable stimuli turn into temptations (Kroese,
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Evers, & de Ridder, 2011). When this happens, the decision situation turns it into a self-
control conflict. Self-control occurs when an individual changes her default course of action,
which would be indulging in the pleasure, and instead successfully resists the temptation
(Muraven & Baumeister, 2000). Note that initiating unattractive activities (like going to the
dentist) is another important aspect of self-control (Giner-Sorolla, 2001), which is, however,
outside the scope of the present chapter.
This framework implies that there are two outcomes upon the emergence of a temptation.
Either the individual succumbs and acts upon her quest for pleasure, or the individual changes
the default course of action and successfully resists. Within this view, it seems to be a truism
that exposure to temptation is bound to increase subsequent consumption on average. The
individual is not always successful so the emergence of temptation should at least every now
and then increase consumption. The intuitive link between exposure to temptation and
consumption can also fall back on a rich history of confirmatory findings in psychology and the
marketing field. Chandon and Wansink (2002) showed that package size is positively related
to consumption amount. Wansink (1996) showed that the consumption of tempting food is
accelerated when the food is stockpiled at home. Federoff et al. (2003) showed that exposure
to olfactory cues of tempting food enhanced craving for this food and its consumption. Shiv
and Fedorikhin (1999) showed that exposing consumers to physically present tempting stimuli
(as compared to pictures of the same stimuli) increased the relative preference for the highly
tempting food option (cake) compared to the relatively less tempting food option (fruit
salad). The delay-of-gratification tradition (for a review, see Metcalfe and Mischel, 1999) also
attests to the fact that exposure to temptation shifts preference towards immediate
consumption of it. Children who were exposed to the physically presented temptation (e.g.
one marshmallow) were much less likely to wait for larger rewards than children who were
exposed to pictorial representations of the temptation (Michel and Baker, 1975).
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Brain research also hints at the validity of the intuitive link between exposure and
consumption. McClure et al. (2004) found neuroscientific evidence that the sight, the smell,
and the touch of a desired object increases impatience. Impatience is assumed to fuel
consumption when the temptation is available (Hoch & Loewenstein, 1991). Another
interesting finding provides evidence that individuals tend to be aware of this intuitive link
between exposure and consumption and try to prevent themselves falling prey to it.
Wertenbroch (1998) showed that consumers are willing to forgo a quantity discount of
hedonic products because they worry that they will overconsume. For instance, they are
willing to pay a higher unit price for cigarettes to avoid stockpiling too many of them at
home. The reason is that they know that having access to more cigarettes will accelerate
their consumption of them. So in sum, this non-exhaustive overview from diverse literatures
provides strong support for the intuitive link between exposure to temptation and its
increased consumption.
Against this backdrop, the ban-or-restrict approach is understandable. Reducing the
consumption of temptation seems to require either the removal of the temptation or the
fostering of a strong capacity to resist it. However this approach tacitly assumes that the
attractiveness of pleasures, and hence temptations, is an invariable given. In this chapter we
explore to what extent the attractiveness of the pleasure is malleable. More specifically, we
explore if temptation may be harnessed in such a way that it pales temptations and in this
way indirectly boosts self-control rather than threatens it. At this point it is good to stress
that exposure to temptations has been shown to support self-control in some circumstances
(Fishbach, Friedman, & Kruglanski, 2003; Pfau, M. & Van Bockern, 1994). This chapter focuses
on the so-called pre-exposure effect (Geyskens et al., 2008) and I will discuss the similarities
and distinctions with other related phenomena in the discussion section.
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The pre-exposure effect
Researchers invited participants for a consumer knowledge test about the flavors of Quality
Street© candy (Geyskens et al. 2008). They received a sheet of paper showing different types
of Quality Street candy and flavor descriptions and were asked to link the wrappings of the
candies to the flavors. The candy was also presented physically, allegedly to support them
with the task because the pictures may not have been very clear. As eating the candy during
the consumer knowledge test would distort the result, the test was a subtle way to prevent
them from eating in this phase (a nudge so to say). In other words, the procedure installed a
temporary task goal that conflicted with eating. Indeed, throughout the studies reported in
this chapter, only a very small minority (< 5%) consumed some of the tempting food in the
first phase. Subsequently, respondents engaged in a taste test, which was presented as a
different study. They rated a new type of M&Ms© on several product characteristics. This task
required them to sample the candy but did not specify the amount needed to provide a valid
assessment. This inconspicuous omission turns the taste test into a self-control problem. On
the one hand participants want to eat more of the attractive candy but on the other hand
they know they realize they shouldn’t eat too much. As a result the amount consumed in a
taste test is a convenient (reversed) index of self-control (Herman & Polivy, 1975). This pre-
exposure to temptation treatment was compared to two control conditions: (1) a group that
was not physically exposed to the candy but only to their pictures and (2) a group that was
not exposed to candy at all in this phase but who engaged in a similar knowledge task about
color and concepts (e.g. grass and green). The researchers found that those who were pre-
exposed to the physically present temptation ate less in the subsequent taste test than those
in both control conditions (Geyskens et al., 2008).
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One line of research efforts has focused on investigating the scope of the effect. We designed
tasks analogous to the consumer knowledge test of the initial studies that were more
involving for children. In one study, children of seven to nine years old had to solve word
puzzles. One group got gummy candy letters to do so, whereas the other group received
carton board letters. In other words, they all received the task goal to form words with
letters, a goal that conflicted with eating in the candy exposure condition. The second phase
of the study was, again, a taste test (of Smarties© this time). The children who had made
word puzzles with candy letters in the first phase subsequently sampled fewer candies than
children who had made the word puzzles with card board letters (Grubliauskiene and Dewitte
2014). In subsequent studies, we asked children to reconstruct flowers that were shown with
either Lego-bricks© or gummy bear candies. So all children got the task goal of reconstruct
flowers from an example, but only for those in the pre-exposure condition, this goal
conflicted with eating the candy. Here as well, children who had been pre-exposed to the
candy bears while they were engaging in the reconstruction task, subsequently ate less
chocolate candies (Grubliauskiene and Dewitte 2015). Another procedure with the same aim
capitalized on Mischel’s classic work on delay of gratification (Michel and Baker 1975). We
were particularly interested in the phase of that paradigm where children deliberately expose
themselves to the food without eating it (i.e. the waiting phase). Some strategic adjustments
to the parameters of the procedure ensured that all children managed to wait through this
waiting phase, effectively exposing themselves to the tempting candy. The procedure is
supposed to install a goal conflict between eating (which is what they are waiting for) and
getting a larger reward (which is their motivation to wait). This procedure also induced less
subsequent consumption of similar tempting candy (de Boer et al. 2015). These studies
suggest that the pre-exposure effect may also work for children, which suggests a relatively
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unsophisticated underlying process, as higher cognition and self-regulation skills have not
reached their full potential for children (Mischel and Baker, 1975).
Many studies about antecedents of eating behavior have relied on female populations only.
This is convenient from a research point of view as health researchers believe that women are
more homogeneous in terms of their endorsement of food restriction goals (Wardle et al.,
2004). Following this tradition in the literature, the initial demonstration of the pre-exposure
effect (Geyskens et al., 2008) has used the young women as the population of interest.
However, the societal costs of overeating are arguably substantial for men as well. Since the
initial studies (Geyskens et al., 2008) our studies have therefore always included men. Not
surprisingly, men ate more. More interestingly, the studies relying on adult respondents have
never shown any reliable gender difference in the strength of the effect. For instance, a
replication of the initial Geyskens et al. (2008) study described above showed that men as
well as women reduced their spontaneous sampling of cookies in the context of a taste test
when they had been pre-exposed to quality street candies in the context of a consumer
knowledge test (Grubliauskiene and Dewitte, 2015). With children, the gender findings have
been mixed: using the various paradigms described above, the studies produced effects
among boys only (Grubliauskiene and Dewitte, 2014), among girls only (de Boer et al. 2015),
or for both genders (Grubliauskiene and Dewitte, 2015). This inconsistent pattern of
moderation by gender among children suggests that ill-understood situational factors may
play a differential role for boys and girls, such as competition proneness or interest in the
distractor activity in phase 1. Further research is needed to identify how the procedure can
be made more robust among children.
Several studies have ventured into assessing the potential of the pre-exposure effect as an
intervention element against overconsumption. On the population dimension, a literal
replication attempt (with Quality street candy during pre-exposure and M&M tasting during
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the subsequent measurement task, Geyskens et al. 2008), showed that the effect replicated
in a South-African student sample, even among those who had suffered food shortage during
childhood (Duh, Grubliauskiene, & Dewitte, 2016). On the longevity dimension, two studies
have shown that the effect survives beyond the immediate situation (15’ delay,
Grubliauskiene & Dewitte, 2015) and even spanning a period of 24 hours (de Boer et al.,
2015). On the independent variable side, preliminary data suggest that (practically
inconvenient) physical exposure may not be required to induce the effect. Following Michel
and Baker’s lead (1975) that subjective reality may trump objective reality in de delay of
gratification paradigm, we found that vivid pictures of peers eating the tempting food seem
to have the same effect on subsequent consumption (Grubliauskiene & Dewitte, 2015). Less
successful was our attempt to extend the procedure to obese participants. Engaging
participants in a geometrical task with chocolate versus wooden sticks reduced subsequent
M&M consumpiong among normal-weight participants (BMI up to 25) but not among obese
participants (BMI higher than 30; Goddyn & Dewitte, 2016a). Further investigations are
needed to replicate this, to understand why there is no transfer from phase 1 to phase 2, or if
and how phase 1 of the pre-exposure procedure could be adapted to produce the effect
among obese participants.
Another factor that substantially affects the scope of the effect is its flavor specificity.
Although the effect seems not very specific with respect to flavor (e.g. not eating cookies in
phase 1 reduces chocolate consumption in phase 2) extending the effect beyond the sweet-
salt flavor barrier, that is, pre-exposing in the sweet flavor domain and assessing the effect
on salty snacks provided only directional evidence (Van Nieuwburg & Kroese, 2015). Using a
larger sample and increasing the comparability among conditions, Goddyn & Dewitte (2016b)
found evidence for transfer from salt to sweet and from sweet to salt that was comparable to
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within flavor transfer. If this finding proves reliable, the pre-exposure effect may be more
useful as a treatment element than thought before.
Underneath the pre-exposure effect
The mechanism underlying the pre-exposure effect has proven challenging to identify.
Knowing the mechanism would not only enhance our understanding of the way people
regulate their food intake but may also come in handy to increase the efficiency of the
technique, with a view to possibly lifting it up to a viable intervention. I discuss three
mechanisms that may underlie the pre-exposure effect: Habituation (Rankin et al., 2009),
cognitive dissonance (Festinger, 1962), and cognitive control (Miller & Cohen, 2001).
Habituation refers to the reduced response to a stimulus after repeated exposure (Rankin et
al. 2009). In the standard habituation paradigm, individuals are exposed to a stimulus (e.g.
little bits of food) repeatedly. After a typical surge of the response after the first few trials
(which is called sensitization), the appetitive reaction gradually fades (Rankin et al. 2009;
Epstein, Temple, Roemmich, & Bouton, 2009). The pattern is distinguishable from satiation
and fatigue as the original response immediately recovers when a new stimulus is
administered at a certain point during the series (Epstein et al, 2009). Epstein et al. (2009)
identified habituation as a potentially important factor in the motivation behind food intake
and its regulation.
The reduced response (eating) after pre-exposure bears some similarity to habituation.
Consistent with such a conceptualization, Geyskens et al. (2008) found that pre-exposure to
the physical stimulus produced slower reaction times to ‘eating’ in a lexical decision task
compared to the control conditions (at least when food was presented again in the second
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phase, Study 2). Further, the finding that the reduced consumption spills over to subsequent
sessions a day later (de Boer et al. 2015) is consistent with the finding of long term
habituation, which reflects the phenomenon that habituation kicks in quicker when a
habituation procedure has taken place before (Epstein et al., 2009).
Other findings are less easy to reconcile, as the habituation goes much slower when the food
stimulus is not consumed (McSweeney and Murphy, 2009; fig. 2). Indeed, using a paradigm
that was inspired by the habituation literature, Morewedge, Huh, & Vosgerau (2010) showed
that imagining eating tempting food (without consuming it) for three times did not reduce
subsequent consumption of the same food compared to a control condition, whereas thirty
repetitions did. In contrast, not consuming during the first phase that occurs only once is
standard in demonstrations of the pre-exposure effect. Moreover, under habituation the
response recovers when different stimuli are shown. The pre-exposure effect has always been
demonstrated using different foods in the two phases (e.g. quality street candy and smarties),
mostly as a tactic to conceal that the two phases are linked. The question is how different a
stimulus should be to override habituation. Epstein and Paluch (1997) found that habituation
was much weaker for a series of slightly varying stimuli (puddings of three different flavors)
than for series of the same stimulus. As the pre-exposure effect has been investigated for
foods that differed more markedly than puddings of different flavors, this finding may suggest
that habituation is not the underlying mechanism.
These superficial inconsistencies are not conclusive, however, because the two research
paradigms are quite different. In the pre-exposure paradigm, the individual is exposed to the
tempting food for several minutes in a row, which may be equivalent with the assignment of a
series of discrete exposures to the same food, a procedural feature that prevails in the
habituation literature. Further, the debate about stimulus specificity has not been settled yet
(Rankin et al. 2009) and perhaps the sweet taste that connects the food stimuli used in phase
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1 and 2 until trumps other factors (e.g. texture in Epstein & Paluch, 1997). Future research
may focus on replications of the pre-exposure effect that are more aligned with the
habituation design. Likewise, specific predictions derived from the habituation theory may be
tested in the pre-exposure paradigm.
Cognitive dissonance, the second potential underlying mechanism, refers to an attitude
change that follows the realization that one’s attitude and one’s behavior are not aligned
(Festinger, 1962). After a so-called induced-compliance procedure where people are gently
nudged to engage in a behavior for which they lack intrinsic motivation, people experience
discomfort because of the dissonance between their attitude and the behavior (Elliot &
Devine, 1994). Changing the attitude is one way to alleviate this discomfort. The effect has
proven robust and received a lot of theoretical attention (Harmon-Jones & Harmon-Jones,
2007). Applications to the eating domain have been scarce, although the idea has been
proposed as a post-hoc explanation (Swee-jin Ong, Frewer, & Chan, 2015).
The pre-exposure effect bears some similarities with the cognitive dissonance effect. In the
first phase, individuals do not eat the presented food although they have a positive attitude
towards the food. This inconsistency may induce discomfort (Elliot & Devine, 1994),
motivating attitude change. The subsequent reduced consumption can then be interpreted as
the result of an attitude that has turned less positive. Grubliauskiene and Dewitte (2015)
tested the cognitive dissonance account but the evidence is mixed. In one study, they added
a condition where they asked individuals explicitly not to eat the candy in the pre-exposure
phase. This prohibition provided participants with a clear justification for not eating during
the pre-exposure phase, compared to a pre-exposure condition without explicit prohibition.
Consistent with the predictions from cognitive dissonance theory, the consumption in this
explicit prohibition condition was indistinguishable from that in the control condition and
higher than in the standard, ‘implicit’ pre-exposure condition. In other studies, they replaced
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the physical temptation with a vivid picture of a consuming peer, which should remove the
discomfort because the unavailability provided a clear justification why they did not eat,
thereby preventing dissonance. Inconsistent with predictions derived from cognitive
dissonance, however, and to our surprise, pictorial pre-exposure reduced subsequent
consumption to the same degree as physical pre-exposure.
More indirect indices of a cognitive dissonance account are not very promising either. Verbal
attitude measurements did not consistently mimic the behavioral effect of the pre-exposure
studies reviewed above. More conclusive evidence will require a strict replication of the
cognitive dissonance paradigm (Swee-Jin Ong et al., 2015).
A third possible mechanism underlying the pre-exposure effect may be derived from cognitive
control theory. Cognitive control refers to the cognitive adaptation processes that are
recruited to deal with a behavioral conflict (Miller & Cohen, 2000). The typical example is the
incongruent trials of a Stroop task where people have to read out loud the ink color of a word
where the word reflects another color, such as the word BLUE in red ink. The correct
response is ‘red’ but the response ‘blue’ interferes and slows down or even trumps the
correct response. Cognitive control theory suggests that individuals adapt to the challenge by
recruiting processes that help them ignore the word meaning and/or focus on the word color.
Although cognitive control literature has focused on domain specific control processes (for an
overview, see Botvinick, Braver, Bargh, Carter, & Cohen; 2001), Kleiman, Hassin, & Trope
(2014) showed that the activated control processes constitute a mindset that can influence
behavior in subsequent but different tasks. This supports my proposal that cognitive control
processes that are recruited during the exposure phase may underlie the pre-exposure effect.
Dewitte et al. (2009) used this model to explain the pre-exposure effect arguing that the first
phase of the pre-exposure procedure induced a behavioral conflict between eating and task
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compliance. The cognitive control processes that this conflict would trigger are believed to
reduce the connection between the food cue and the reward in phase 1 (Verguts & Notebaert,
2008), as the physical consumption and hence the ‘delivery of the reward’ is omitted.
Typically, tempting food that is in front of people provides them with a reward because they
put it in their mouths and swallow. The pre-exposure phase may be considered as a phase
where the link between the cue and the rewarding behavior is weakened by task goal-induced
cognitive control processes, which then spills over to reduced consumption of similar food in a
subsequent phase. In other words, cognitive control processes may manifest in two ways.
They may reduce the strength of the temptation (like when participants learn to ignore the
words in the Stroop task, Botvinick et al., 2001) but they may also strengthen the control
processes (when slowing down of the decision after a conflict; Kleiman et al., 2014).
One implication is that suppressing the behavioral conflict in the first phase by self-control
support tactics would suppress the pre-exposure effect. De Boer et al. (2015) manipulated the
intensity of the behavioral conflict by asking children to focus on either the hedonic features
of the exposed temptation or on its cold aspect. Although both conditions led to success in
the first phase, we infer that focusing on the cold aspect reduced the behavioral conflict in
phase 1, based on Michel and Baker’s (1975) seminal finding that focusing on the cold aspects
of rewards supported resistance. A weaker behavioral conflict reduces the need for control
processes to be recruited. Without cognitive control processes geared at weakening the link
between the food cue and the reward, there cannot be any spill-over. Consistent with the
prediction based on cognitive control, focusing on the cold aspect in the first phase removed
the pre-exposure effect.
We also know that people learn to ignore the word meaning when dealing with behavioral
conflict in the Stroop task (Miller & Cohen, 2001). If cognitive control is at play, we could
expect that being exposed to sweet temptation may lead to people ignoring the tempting
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dimension (sweetness). Consistent with this prediction, an unpublished study (Grubliauskiene;
2014, p. 43) found that pre-exposure to sweet foods reduced the importance of the sweetness
dimension in the conceptual space of juices.
It is less clear why exposure to pictures also works as a picture may not induce a behavioral
conflict. Across studies it seems to be the case that exposure to vivid pictures reduces
subsequent consumption (Grubliauskiene & Dewitte, 2015, study 2) whereas exposure to small
pictures increases subsequent consumption compared to the control condition (Geyskens et
al. 2008, study 3), analogous to the findings by Kroese, Evers, & de Ridder (2010). Until this
has been tested in one single study, this finding remains very preliminary. However, we may
speculate that small pictures increase the appetite for the food somewhat but not enough to
reach a critical level (Gilbert, Lieberman, Morewedge, & Wilson; 2004, Kroese, Evers, and de
Ridder, 2009) whereas vivid pictures do induce a conflict between the urge to get up and
fetch the food in the shop or the cupboard and the current impossibility to act upon the
intention in the task at hand. We call for future research to shed light on this question. So in
all, cognitive control seems to survive the empirical tests a bit better than the competition
but further research will be needed to support this conclusion further.
General Discussion
Although promising and remarkably robust across situations and populations, I acknowledge
that much remains to be explored. In this final section, I discuss the potential of the pre-
exposure effect for enhancing self-control. I first discuss the distinction with two similar
phenomena that have been reported in the literature. I then spell out the open questions that
need to be addressed to determine how useful the effect may be for enhancing self-control. I
then discuss the relation between the pre-exposure effect and nudges and show how
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attention for the long-term effects of nudges could give rise to a behavioral engineering
approach to tackle self-control problems (Bruyneel & Dewitte, 2016).
Related but distinct phenomena Fishbach, Friedman, and Kruglanski (2003) demonstrated that exposing people to pictures of
tempting food (e.g. in magazines) reduced subsequent desire to eat tempting unhealthy foods
among young women. Kroese et al., 2009) replicated this finding for actual consumption. The
effect has obvious procedural similarities with the pre-exposure effect described in this
chapter. Nevertheless, a crucial difference seems to be the role of the food restriction goal.
Fishbach et al.’s (2003) original report as well as the behavioral replication reported later
(Kroese et al., 2009), showed that the accessibility of food restriction goals moderated the
effect. The data suggest that being exposed to temptations activates a restriction goal (if
available), which in its turn boosts resistance to subsequent food temptations. In contrast,
the effects in the Geyskens et al. (2008) studies were not moderated by the availability of
restriction goals. Furthermore, the activation pattern of the food restriction goal did not
correspond to the subsequent consumption data. Although exposure to both physically present
and pictured temptations were found to activate people’s food restriction goal (Geyskens et
al, study 1), thereby replicating Fishbach et al. (2003), only the exposure to the physically
presented temptation reduced subsequent consumption (Geyskens et al, study 3a&b). In
addition, the repeated finding that the effect replicates in young children (de Boer et al.,
2015; Grubliauskiene & Dewitte, 2014) suggest that the restriction goal is not important in the
pre-exposure effect. These data seem to suggest that the pre-exposure effect is a distinct
phenomenon but the differences may also result from ill-understood situational variations
that determine the role of the restriction goal. Future research is needed to determine how
different the phenomena are and how they interact or complement each other.
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Another effect that shows superficial similarities to the pre-exposure effect is the so-called
inoculation effect that was introduced in the sixties as a tool to enhance people’s resistance
against persuasive attempts (McGuire and Papageorgis, 1961). The idea is that the individual
undergoes a mild persuasive attempt in a situation where it is not harmful. This treatment
subsequently fosters the emergence of cognitive defense mechanisms that are available when
a more threatening persuasive attempt arises. The technique has been further elaborated in
the field of communication science. Pfau and van Bockhern (1994) showed that young
adolescents can be inoculated against future social pressure to smoke, way before the peer
pressure to start smoking appears. Godbold and Pfau (2000) further showed the technique to
be effective in fostering resistance to alcohol use. The similarity between the two effects
relies on the assumption that social pressure and temptation both address the affective
system, viscerally motivating the individual to comply with the pull.
Two experiential differences set the two procedures apart. The pre-exposure effect does not
seem to rely on emerging cognitive defenses against the ‘persuasion’ but on relatively
unsophisticated coping strategies, as the effect is robust among children of 7 years. In
addition, the pre-exposure effect typically uses exposure to a temptation that can be in
principle be consumed in the first phase, in contrast to the inoculation procedure, which uses
harmless persuasive attempts. The finding that exposure to vivid pictures may also reduce
subsequent consumption may, however, be more similar to the classic inoculation effect,
although one interpretation is that the vividness makes the temptation virtually accessible
(Mischel and Baker, 1975). In spite of a few obvious differences, the processes may be similar
on a deeper level and future research will have to establish to what extent the effects rely on
similar mechanisms or to what extent they may complement each other.
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Future Research
First, we do not know what the pre-exposure to temptation triggers exactly during the first
phase of the pre-exposure procedure. Is the spill-over related to the sweet nature of the two
stimuli, or to the fact that they are both treats? If the spill-over is related to the sweet taste
of both objects, exposure to candy would reduce subsequent consumption of for example
grapes (which would be unfortunate) but if it is related to the treaty nature of both stimuli, it
would spill over to crisps. As you can imagine, many other characteristics may carry the
effect over to the next phase. Finding out how people do this spontaneously would not only
be relevant for descriptive purposes but such research efforts may also beg the question as to
whether this framing process is malleable. Could we design instructions that draw attention
to the right aspect of the exposed stimulus within the pre-exposure procedure to maximize or
optimize the spill-over effect?
We also do not know whether the procedure works beyond sweet foods. Preliminary evidence
suggest that the effect crosses flavor categories (Goddyn & Dewitte, 2016b) but we need
more evidence whether or not it generalizes to salty snacks, fast foods, drinks (e.g. soda or
alcoholic drinks), or even to activities (e.g. social media overconsumption) or objects (e.g.
luxury goods).
A third question pertains to the robustness of the effect against delay. Preliminary findings
are promising (de Boer et al., 2015) but there is no information on what factors may play a
role in the longevity of the effect and if these factors could be harnessed to improve the
robustness of the effect. We have experienced that drawing attention to food after the pre-
exposure phase tends to reduce the behavioral effect immediately, whereas inserting 15
minutes of non-food related tasks does not affect the effect at all (Grubliauskiene & Dewitte,
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2015). This suggests that food-related thought may interfere with the changes, which raises
the question as to how long the inferred consolidation phase lasts.
A fourth research opportunity is related to its applicability to resistant populations. In the
food domain, we know that obese individuals are notoriously resistant against behavioral
treatments because food has a disproportionate pull on their attention and their approach
behavior (Castellanos, Charboneau, & Dietrich, 2009; Schag et al., 2013). On the one hand,
these characteristics may lead to a stronger behavioral conflict in the first phase (provided
the procedure can be fine-tuned to make sure they pass that first phase successfully, cfr de
Boer et al., 2015), which may provide a leverage to boost the effect. On the other hand,
these characteristics may also reduce the effectiveness of the first phase as they may feel
socially prohibited to eat. We know that ‘explicit prohibition’ to eat removes the pre-
exposure effect (Grubliauskiene & Dewitte, 2015). In other words, among particularly
motivated individuals, the pre-exposure procedure may fail. Indeed, initial evidence shows
that obese participants live through the first phase but do not reduce their subsequent
consumption (Goddyn & Dewitte, 2016a). Relatedly, and provided the effect generalizes to
other domains, it may be interesting to test if the effect could be useful in treating addiction.
In general, the strength of the behavioral conflict may prove an important parameter to
manage the effect (e.g. de Boer et al, 2015).
A fifth research opportunity is related to the nature of the first phase. The assumption has
always been that the pre-exposed individual should not consume the food in the first phase,
that is, successfully resist the physical temptation (Geyskens et al., 2008). Although this
assumption sets high procedural requirements for the applicability of the procedure, it has
never been tested. It may be that not success but engaging with the food in an unusual way
plays the pivotal role.
19
From a cognitive control perspective, one could even make the argument that failure in phase
1 may be better in triggering control processes than success. Indeed, the Gratton effect
(Gratton et al., 1993), which reflects the increased effort people invest in incongruent Stroop
trials after a failure in a previous incongruent Stroop trial, suggests that failure may be more
effective in triggering control processes (see also Kleiman et al., 2014). If the pre-exposure
effect works in the face of failure as well, it may open up application areas with resistant
populations (e.g. young children).
The role of social processes provides a final interesting research opportunity to explore
expansion of the scope of the effect. Does vicarious pre-exposure exist? Would seeing
someone else actively engaging with food without consuming it reduce subsequent
consumption (and why, and when)? Social norms may also be managed to improve the effect.
Think of a reception situation. Tasty snacks are provided at a time people tend to be hungry.
Although they want to indulge, the implicit norm at reception is to keep consumption
moderate. Would this moderation by social norms have similar effects as the stylized pre-
exposure effect reported here?
Conclusion: towards a behavioral engineering approach
In this chapter I identified what we know about the pre-exposure effect and what needs to be
done. An important question I would like to address is the question as to whether the pre-
exposure is just another, though rather convoluted nudge? Ignoring the cost, the success of a
nudge is typically assessed in terms of its success of achieving the intended behavioral change
in the presence of the nudge. However, from a policy point of view, long-term effects are
relevant as well (Frey & Rogers, 2014). What the pre-exposure effect and the role of the
behavioral conflict illustrate, is that nudges that are very strong (e.g. cold ideation, de Boer
et al. 2015) and hence potentially very successful in the short run, may not be the best
20
nudges in the long term. Strong nudges may constrain “operational” freedom of choice, and
hence reduce the need to actively resist the temptation. For instance, putting candy in a
vending machine in a remote corner of the school may be very effective in reducing
consumption at school (although the students can in principle still buy the candy). However,
such policy may not trigger the behavioral conflict that is believed to trigger the control
processes that help students resist (Bruyneel & Dewitte, 2016). Moderately strong nudges, on
the other hand, may be less effective in stimulating the desired behavior in the present, yet
if they do, they may produce long-lasting effects, even outside the school context. For
instance, rather than putting the vending machine in a remote section, the school may decide
to add fruit to the vending machine and heavily support it through advertising or subsidizing.
Probably this policy will be less successful in the short run if it comes to reducing candy
consumption. However, such a measure may induce behavioral conflict in some students,
which may help these students to develop a strategy to choose the fruit that may survive
outside of the decision situation. At this point social processes may kick in to help spread the
new behavior (Laland 1994).
This conceptual analysis suggests a new research angle on the effectiveness of nudges. How
do we determine the optimal level between short and long-term when designing choice
situations? The same analysis also suggests that the balance between short and long term
effect may depend on a variety of factors, such as the direction and intensity of pre-existing
preferences, motivational factors, population characteristics, social norms, and the degree of
situational control the policymaker can exert. The pre-exposure effect invites us to look
beyond the immediate choice situation and start engineering behavior also in the long run
(Bruyneel and Dewitte, 2016).
Acknowledgments
21
The author thanks Marieke Adriaanse, Sabrina Bruyneel, Kentaro Fujita, and Hannelore
Goddyn for valuable comments on earlier drafts of this chapter. The author acknowledges
financial support from the EU (FP7) funded TEMPEST and CONCORT projects and the FWO.
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