Cognitive Dissonance : A suggestible need for
coherence
Joshua Hagège
June 6, 2016
Abstract
Festinger’s formulation of cognitive dissonance theory (1957) has had
a notable impact on social psychology. More specifically, the notion that
our past choices affect our future behavior is at the core of the theory.
Using the free-choice paradigm (FCP), it has been shown that after having
chosen between two similarly rated items, subjects tend to reevaluate the
chosen items as more attractive and the rejected items as less attractive.
After 50 years of research using the FCP paradigm, Chen and Risen (2010)
revealed a methodological flaw casting doubt on most of the previous
studies. Izuma and colleagues (2010) still found a genuine effect of choiceinduced preference change after controlling for Chen and Risen’s artifact
but introduced a new bias. Controlling for this bias, Salti and colleagues
(2014) showed that this effect strongly correlated with episodic memory.
Several arguments support the hypothesis that choice-induced preference
change depends on high-level cognitive abilities. In the present work,
we aimed at establishing the extent to which choice-induced preference
change effect can be influenced by top-down modulations. To do so, we
replicated Salti and al’s results and introduced a manipulation condition
in order to influence the choice-induced preference change effect. Our
results contribute to the understanding of the phenomenon by showing
that choice-induced preference change effects can be suggested by topdown influences.
Colleagues : Mariam Chammat and Lionel Naccache
Internship Supervisor : Lionel Naccache
1
Déclaration d’originalité
Par la présente déclaration, je certifie l’originalité de mon mémoire de master 2.
En effet, bien que la théorie de la dissonance cognitive et son lien avec le
paradigme du choix-libre aient déjà été grandement étudiés, plusieurs questions
au sein d’un débat théorique plus grand sur la nature même du changement de
préférence induit par le choix restent non résolus. Notamment, la question de
l’automaticité de l’adaptation des valeurs reste non élucidée, et notamment la
place des influences conscientes au sein de ce phénomène.
2
Déclaration de contribution
La réalisation de ce projet comprenait 5 moments essentiels : la conceptualisation, la programmation, la passation des sujets, l’analyse de données et
l’écriture. Toute l’équipe a participé à la conceptualisation qui consistait en
un travail de lecture de la littérature, de discussion théorique, et de mise en
place d’un paradigme adéquat. J’ai réalisé, avec l’aide de Mariam Chammat, la
programmation de l’expérience qui consistait principalement à la modification
d’une expérience déjà existante pour la faire correspondre à notre paradigme.
J’ai réalisé l’intégralité de la passation des sujets (73 présentés ici + une quinzaine de pilotes) avec l’aide de Mariam Chammat. J’ai réalisé les analyses de
données sur Matlab ainsi que sur R, avec vérification et conseils de Mariam
Chammat et de Lionel Naccache. Enfin, j’ai réalisé l’écriture de ce mémoire
qui a bénéficié de la relecture et des conseils de Mariam Chammat et de Lionel
Naccache.
3
Contents
1 Introduction
1.1 Cognitive dissonance theory . .
1.2 A methodological revolution . .
1.3 A theoretical debate . . . . . .
1.4 Cognitive dissonance : a link to
1.5 An automatic process ? . . . .
. . . . .
. . . . .
. . . . .
the past
. . . . .
2 Method
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
5
6
9
11
12
13
16
3 Results
20
3.1 Manipulation of choice-induced preference change . . . . . . . . . 20
3.2 The choice-induced preference change in the control condition
(Part A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4 Discussion
29
5 General Conclusion and Perspectives
32
References
32
4
1
Introduction
Several paradigms are used to explore consciousness. Researchers can use them
in order to explore conscious perception, or conscious action. Consciousness
however is not restricted to perception or action, but can be extended to the
notion of conscious opinion.
The dynamics of the creation of this conscious opinion can be studied in
the lab. Indead, researchers have developed several tools in order to of explore
human cognition, and one way to investigate the emergence of one’s own opinion
in a laboratory would be to use Cognitive Dissonance theory.
5
1.1
Cognitive dissonance theory
When looking at the social psychology literature it is easy to see that Cognitive
Dissonance theory has made a notable impact in this field. Since Leon Festinger’s [Festinger, 1957] formalization of this theory, cognitive dissonance has
been studied in different ways and in several paradigms. But what exactly is
meant by cognitive dissonance?
Cognitive dissonance refers to the disharmony or the discomfort a person
is faced with inconsistencies in their cognitions or actions. Festinger’s theory
argues that inconsistency upsets us and drives us to take action in order to
reduce this feeling of discomfort. The greater the inconsistency, greater will be
the feeling of discomfort, and the more one has to find ingenious ways of reducing
their dissonance. One of the main points of Festinger’s theory is that it is not
that we will have to be more ingenious, but that we will be more ingenious. It
is not only that we don’t like to be inconsistent, but it is that our behavior will
be driven to reduce this inconsistency.
Another point that distinguishes cognitive dissonance theory from other consistency theories is that the theory uses the concept of cognition. Using this
concept, the theory can apply to a lot of psychological concepts, and thus is on
the one hand, very general, and on the other hand, testable in many different
ways.
Before going further in the description of precises exemples of paradigms,
let us take an example of how cognitive dissonance can be created.
Imagine that sunny days are about to arrive, and that you have planned to
go and enjoy one week ”at the beach” (let’s say Les Sables d’Olonne). But now,
add the fact that, for some reasons that don’t concern me, you really want to
lose a few kilograms before showing your perfect body minus few kilos to the
world. You have still one month to loose weight, and you decide, for example,
to stop eating fatty food (cognition A). Two weeks later, your plan fails, and
you start eating the forbidden food (cognition B). Those two cognitions (A and
B), are very inconsistent and create in us a feeling of discomfort that we will
tend to reduce. One way would be to change our behavior. In our example,
you can simply stop eating the actual food. Then cognition B will be abolished
and nothing would be in conflict with cognition A (except maybe the memory
of having eaten fatty food). But changing our own behavior is not the only way
to reduce this inconsistency : we can also change our attitude, and this last
strategy is much easier than changing your behavior. You just need to change
your attitude toward fatty food by claiming that, after all, after two weeks of
big efforts, you deserve this reward! Also, this food will motivate you to eat less
during the next two weeks. Or you can say that, it had been such a long time
that you hadn’t seen your great friend that cooked this delicious dinner for you,
and not enjoying the food would be an affront to your friendship. Now, we have
a new cognition that reduces the initial inconsistency.
After more than 50 years of research since the initial formulation of the
theory, a rich research framework has emerged. The most important paradigms
that have been explored are :
• The Induced-compliance paradigm
• The Effort justification paradigm
• The Misattribution paradigm
6
Figure 1: Attractiveness of the chosen and rejected alternatives following a decision. Source: Adapted from Brehm (1956), from Joel Cooper Cognitive
Dissonance : fifty years of Classic Theory
• The Free-choice paradigm
In the present work we use the free-choice paradigm which was developed
by Jack Brehm in the 1950’s [Brehm, 1956]. In its original version, subjects
(that were exclusively female), were asked to rate households gadgets, as mixer,
blenders, etc... Then, he told them that the research firm allowed him to let the
subjects go with one gadget and asked subjects to make a choice between two
items.
According to Festinger’s theory, if one’s make a choice between two things
that they like similarly, they will be subject to a feeling of discomfort due to
the facts that : First, they reject something that they would have liked to have,
second, they say that they prefer something compared to the other thing, but
that could be untrue in case the two items turn out to be actually liked equally.
Thus, subjects could adopt two strategies. Firstly, they could change their
behavior by choosing none of the items. Obviously, it would not be the most
profitable strategy. Secondly, they can modify their attitude towards those
items, and this can be evaluated by asking subjects to rate all the items a
second time.
And this is exactly what is asked of subjects in this paradigm : participants
are asked to rate all the gadgets all over again in a second Rating.
Two conditions are then compared
• The Hard Decision condition : both items were rated similarly
• The Easy Decision condition : both items were rated very differently
Once again, according to Festinger’s theory, the Hard Decision condition
is supposed to create more dissonance for the participant for the reasons that
7
were previously explained. Thus, subjects would be even more driven to regulate
their dissonance in the Hard Decision condition. This leads us to the following
prediction : the difference in rating between the first rating and the second
rating for the items that have been chosen or rejected (also called spread of
the alternatives), should be bigger for the Hard Decision condition than for the
Easy Decision condition. This is indeed what Brehm observed as summarized
in the Figure 1.
The spread is calculated in the following way :
Spread = (Rating2chosen -Rating1chosen )-(Rating2rejected -Rating1rejected )
Brehm’s study used the free-choice paradigm to examine the mechanism
of choice-induced preference change, and it was in total accordance with the
Cognitive Dissonance theory.
This is how one of the main paradigms of the theory was born and led
to decades of research on the topic. The theory was considered as one of the
strongest in social psychology. All studies tended to confirm the existence of this
phenomenon. This experimental success that was robustly replicated in many
different laboratories around the world can be seen as the strongest property of
this theory : its reproducibility.
However, this experimental success could be attributed to another cause :
a methodological flaw that tends to drive the results in the same significant
direction each time. And this is precisely what Chen and Risen discovered and
demonstrated in 2010.
8
Figure 2: Regression to the mean.Adapted from [Chen and Risen, 2010]
1.2
A methodological revolution
Hard time for cognitive dissonance
In 2010, Chen and Risen [Chen and Risen, 2010] published a seminal article in
the history of the free-choice paradigm (FCP). They reported that the spread
observed in the FCP could be observed even under conditions of stable preferences. Their claim relies on two assumptions :
• Rating are noisy measures of subjects’ real preferences.
• Subjects’ choice give additional information about their real preferences
Under these assumptions if one rates the items A and B equally, and decides
to choose item B when he has to make a choice, it would mean that he actually
prefers item B compared to item A, and that he respectively overestimated and
underestimated their rating for the item A and B. Then, as a result of regression
to the mean, during the second rating, the new rating would decrease for item
A, and increase for item B. (Figure 2)
In order to test this assumption, Chen & Risen have proposed a simple and
ingenious test : they suggest that in addition to the original condition RatingChoice-Rating (RCR), a new control condition Rating-Rating-Choice (RRC)
should be added. According to their hypothesis, they made the prediction that
there would be no significant difference in spreading alternatives between the
two conditions. In other words if the classically obtained result only reflects
noise, one would expect the noise to be equal in both RCR and RRC condition.
And this is exactly what they found : whether there was a choice between the
two ratings (RCR) or no choice between the two ratings (RRC) the change
in ratings from rating 1 to rating 2 was not different. This led them to the
conclusion that the choice-induced preference change either doesn’t exist (and
was only a measure of noisy ratings), or that it is at least much weaker than
previously thought.
9
Figure 3:
Behavioral results for
[Izuma et al., 2010]. Bars indicate the change
preference
change
from
in preference for foods from Preference
task 1 to Preference Task 2 (Ratings in Preference task 2 minus those in Preference task 1) in each
condition. *p¡0.05; ***p¡0.001, paired t-test one-tailed.
A new hope for cognitive dissonance
Since Chen and Risen major study, the use of such a control condition seems
to be a prerequisite for the study of the free-choice paradigm and results can
only be interpreted in light of this new control condition. Only a few studies
have taken Chen & Risen’s criticism into account and tested the paradigm with
a control condition.
For exemple, Izuma and al [Izuma et al., 2010], found a genuine effect of
choice-induced preference change despite Chen and Risen’s criticism. In other
words they report a significantly larger spread in the RCR condition than in
the RRC condition. However when examined more closely during the second
rating of the RCR sequence of Izuma et al.’s study each item was labeled with a
reminder of the choice the subject had previously made on that item (e.g.: ’you
rejected it’). Obviously, such a reminder was delivered only in the RCR sequence,
given that in the RRC sequence the choice was made after the second rating.
As a consequence, Izuma et al. did not contrast RCR with RRC conditions, but
they rather compared ‘RCR+explicit choice reminder’ versus RRC condition.
This asymmetry between RCR and RRC conditions makes it simply impossible
to draw clear conclusions. In addition, the results obtained by Izuma et al.
with the reminder shows that there might be a link between the availability
of the choice information (episodic memory in a more ecological context) and
choice-induced preference change. And this link falls within a bigger theoretical
debate.
10
1.3
A theoretical debate
Indeed, despite the fact that the free-choice paradigm has been used for several decades, the precise mechanisms subtending such choice-induced preference
changes remain unclear. We can easily divide the literature in two opposite
theoretical accounts.
On the one hand, we can find many different models calling for high-level
processes, self-related or metacognitive top-down accounts of choice-induced
preference change. The original theory [Festinger, 1957] belongs to those types
of models (even if Festinger does not give any account for precise mechanisms,
as well as other reformulations of it, for a review see [Cooper, 2007]). Moreover,
choice-induced preference change could also be explained by other models departing from cognitive dissonance. For example, we can cite models such as selfconsistency theory [Aronson, 1968], and self-affirmation theory [Steele, 1988].
Despite differences between those two, they both argue that choice-induced
preference change result from discrepancies between one’s self concept and
one’s decision. Self-Perception model postulates that choice-induced preference change exists without any discomfort due to any inconsistency, but as a
result of inferences of his own behavior without any direct access to an encapsulated value system [Bem, 1973]. Furthermore, neuroimaging investigations
showed the implication of executive network such as the anterior cingulate cortex ([Izuma et al., 2010], [Van Veen et al., 2009]). These findings support the
idea that high-level processes are involved for choice-induced preference change.
On the other hand, other studies support the idea that choice-induced preference change does occur without involving any high-level process such as memory
or executive controls, and without any involvement of the concept of self, in a
very automatic way. Indeed, regarding to memory, choice-induced preference
change have been found in amnesic patients [Lieberman et al., 2001], and in normal controls with very long delays between the two ratings [Sharot et al., 2012].
Moreover, studies showed same effects in young infants and Capucin monkeys,
who are supposed to have a less developed sense of the concept of self and a less
effective executive control [Egan et al., 2007]. Additionally, other neuroimaging
studies have found correlations between choice-induced preference change and
the activity in sub-cortical regions such as the striatum, itself included in the
motivation network, that support the idea of a genuine modification of values
[Izuma et al., 2010], [Sharot et al., 2009]
However, most of these studies were conducted before Chen and Risen’s
criticism. Thus, they show methodological flaws that do not allow us to draw
any reliable conclusions.
11
Figure 4: Experimental paradigm for the ‘Reminder’ and ‘No reminder’ groups [Salti et al., 2014]. The experimental paradigm included 5 stages:
Rating 1, Choice 1, Rating 2, Choice 2 and Memory test. The procedure differed between the
‘Reminder’ and ‘No reminder’ groups in Rating 2 and Memory test. In Rating 2, previous choice
(either subject’s or computer) was indicated for the ‘Reminder’ group (left panel) but not for the
‘No reminder’ group (right panel). Additionally, subjects in the ‘No reminder’ group performed a
memory test designed to check whether they have remember the information corresponding to the
reminder present in Rating 2 for the ‘Reminder’ group
1.4
Cognitive dissonance : a link to the past
In order to shed some light on this theoretical debate, it seemed mandatory to
replicate Izuma’s experiment in a more controlled manner but also to disentangle
the link between memory and choice-induced preference change. To this aim
Salti and al. [Salti et al., 2014] designed experiments that could address these
questions.
Their first experiment had two objectives. Firstly, replicate Izuma’s results
with the reminder and compare it with a condition without reminder. Secondly,
investigate the effect of memory on the spreading of alternatives. In order
to test both of these objectives, they replicated Izuma’s experiment, with two
crucial differences. Two groups of participants had been tested. One of them
did exactly the same experiment as Izuma did. The second group differed in
the facts that, first, they did not have any reminder during their Rating 2,
second, they had to perform a memory test at the very end of the experiment.
During this memory test, for each destination that had been coupled during the
first choice, participants were asked if they remembered if they had chosen or
rejected the currently displayed destination (see figure 4)
This experiment showed two mains results. First, they replicated Izuma’s
results. But their design allowed them to test the interaction of the condition
(RCR/RRC) and the presence of the reminder (reminder/no reminder). This
ANOVA showed a critical interaction between those factors : the reminder made
12
Figure 5: Effect of memory on spreading of alternatives. Salti 2014
interaction between the sequence (RCR/RRC) and the memorization of the choices was significant
(* p = 0.019). The difference between the spread in the RCR and the RRC sequences was significant
only in pairs for which the choice was remembered (** p,0.01, paired t test, two tailed).
subjects show a greater choice induced-preference than those who hadn’t seen
any reminder, only for the RCR condition. Moreover, there was still an effect
of choice-induced preference change without the reminder. One could wonder
whether this effect was due to the availability of choice information during the
second rating. This question can be assessed by subjects performance during
the memory block. The second main result of the experiment is that RCR
remembered choices showed a greater spread than RCR forgotten, and than
RRC (both forgotten and remembered) choices.
This experiment reveals the importance of the availability of choice information in relation to the magnitude of preference changes. Another experiment was done in the same article with very few differences in order to do a
proper analysis of the two factors : condition (RCR/RRC), and memory (remembered/forgotten). In this second experiment, the memory block did not
only concern the choices made in the Choice 1 block, but also the choices made
in the Choice 2 block. This second experiment showed a critical interaction
between the two factors condition, and memory (See figure 5)
These findings add a very new factor to the understanding of choice-induced
preference change : its correlation with episodic memory.
1.5
An automatic process ?
So far, we see that in spite of the pre-Chen and Risen findings that tend to
show that low-level cognitive abilities are involved in choice-induced preference
change, there are several arguments suggesting that this phenomenon relies on
high-level process. First, Chen and Risen’s [Chen and Risen, 2010]argument
supports the idea that the choice induced preference change effect observed
13
in the free-choice paradigm results from a progressive accumulation of evidence
about one’s own real preferences. Second, the fact that Izuma’s [Izuma et al., 2010]
reminder has a strong influence on the magnitude of preference change. Third,
Salti [Salti et al., 2014] showed a strong link between preference change and
memory. Fourth, Chammat et al. (in prep) shows that the activation of the
hippocampus (as shown both in the fMRI and SEEG) correlates with the interaction between the two factors condition and memory.
Taken together these different lines of evidence tend to go against the lowlevel automatic view of choice-induced preference change. Rather than being
an automatic process, choice-induced preference change seems to be influenced
by high level processes. In order to further examine the automaticity of this
phenomenon one may wonder whether this phenomenon can be influenced by external manipulations. Indeed if one can influence subjects’ tendency to change
their preferences according to their choice then it would constitute evidence
against the automaticity of choice-induced preference change. According to
cognitive dissonance theory, this would mean that rather than automatically resolving their dissonance by changing their preferences, subjects’ behavior would
be influenced by external factors.
Several studies have shown that our behavior can be oriented, influenced, or
primed by different types of external simulations (images, sounds, smells etc...
[Kuzyakov et al., 2000]). Notably, it has been shown that our judgments can
also be influenced. Tversky and Kahneman have identified several heuristics and
biases that orient our judgments [Tversky and Kahneman, 1974]. For example,
the estimation of one value deviates from a starting point to a final estimation.
This starting point can be suggested, and lead to a final answer that would have
been different than if the starting point had not been suggested. This bias is
called anchor bias.
Many other researchers have shown that one’s behavior can be influenced
by simple sentences about stereotypes. Indeed, sentences about how subjects
should perform on a given task seem to influence their performance on this task
[Cheryan and Bodenhausen, 2000]. Sentences can also influence future behavior
without that subjects realized any relationship between sentences and the task
they performed ([Bargh et al., 1996], [Nelson and Norton, 2005]).
More specifically, the concept of stereotypical threat has been created to describe how the stereotypes can influence one’s performance by suggesting how
they should act. This suggestion creates motivation not to conform to it, which
adds some pressure and leads to a decreased performance [Steele and Aronson, 1995].
Indeed, expectancy effects seem to have an influence on cognitive operations,
from basic stimulus processing to higher cognitive functions [Schwarz et al., 2016],
[Schwarz and Büchel, 2015].
As it is possible for one’s behavior to be influenced by conscious influences
such as simple sentences, one can wonder whether choice-induced preference
change effects are also suggestible.
The question of the automaticity of the choice induced-preference change is
still subject to debate, and notably, the question of inter-individual differences.
It seems very intuitive that people can react differently to cognitive dissonance,
and one can wonder whether those differences are due to one’s own tendency
to be coherent. One way to address this question would be to test whether coherence tendency manipulation might affect the resolution of dissonance. More
specifically one could orient subjects in a way to reinforce or decrease their ten14
dency to be coherent with their choices. If manipulating one’s own tendency
to be coherent can modulate whether they show a choice-induced preference
change, this would show that, firstly, choice-induced preference change relies on
one’s own tendency to be coherent, secondly, this phenomenon is not necessarily
an automatic one.
To this aim we designed an experiment with 3 groups, including 2 groups of
interest manipulated in order to increase or decrease their coherence tendency
depending on the group and 1 control group. This experiment is composed of
2 parts, including a first control part without any manipulation and a second
part with manipulation.
First, we predicted no differences between the three groups within the first
part. Moreover, we predicted that increasing one’s own tendency to be coherent would increase choice-induced preference change effect, and vice versa, and
that we will find this difference only in the part B across the different groups.
According to all the literature exposed in this introduction, we predicted to find
a difference of the interaction of the two factors Condition and Memory across
the different groups.
15
2
Method
Ethics Statement
This experiment has been approved by the Pitie-Salpêtrière ethical committee. All the 73 subjects gave their written informed consents, and were paid
10 Euros to participate in the experiment. All investigations were conducted
according to the principles expressed in the Declaration of Helsinki.
Participants
27 healthy participants were included in the Control group (12 women; age
M=23.25 years old; STD=3.02), 24 healthy participants were included in the
Coherence group (13 women; age M=22.95; STD=2.83), and 22 healthy participants were included in the Incoherence group (11 women, age M=23.36;
STD= 3.07) leading to a total of 73 participants. They reported normal, or
corrected-to-normal, visual acuity.
Stimuli
Stimuli consisted of 160 (80 for each part : A & B) equalized images of
holiday destination (subtended 5.3 ˘ of the visual field), with the name of the
destination written underneath it, on the center of the screen (font size=30).
In ’Rating’ blocks, one image appeared at the center of the screen in each trial,
whereas in ’Choice’ blocks, two targets were presented 4.8 ˘ off-center, to the
left and to the right, in each trial1 . Manipulation stimuli were quotes written
in french displayed on the desktop background.
Procedure
The experiment was composed of 9 blocks and a manipulation period : 4 blocks of
rating (Rating 1-A, Rating 2A, Rating 1-B, Rating 2-B), 4
blocks of choice (Choice 1-A,
Choice 2-A, Choice 1-B, Choice
2-B), and a memory block for
every groups of subject (Control - Coherence - Incoherence).
The only difference between
the groups was the content of
the manipulation (See figure 6).
The part A of this experiment
serves as an intra-group control
in order to be able to find the
classical choice-induced preference change effect in each group
before subjecting them to any
kind of manipulation.
The
block B is in fact the block of
Figure 6: Experimental paradigm
interest in which we predicted to find differences across the three groups.
1 See
preliminary preparations to see how we decided the number of stimuli
16
• Part A:
Rating 1-A: The experiment started with a first rating (Rating 1-A),
which included 80 trials. Each trial began with a fixation point presented during 1.5-seconds. Then one vacation destination was centrally presented for 3 seconds, followed by a blank screen lasting till
subjects gave their response. Subjects were requested to report how
much they would like to spend their vacation in this destination using an eight-point scale (1 = ‘I do not want to go there at all’, 8
= ‘I definitely want to go there’). Subjects responded using the 1–8
number pad buttons of a regular keyboard.
Choice 1-A: The first block was followed by a choice (Choice 1-A), which
included 20 trials (40 destinations were coupled). In this block, every trial started with a fixation point presented during 1.5 second.
Then, two destinations were presented side-by-side for 5 seconds.
Subjects had to report manually their choice using the left/right arrows keyboard keys. Importantly, destinations was coupled according
to Rating 1-A block. Each couple of destinations was composed of
destinations noted similarly.
Rating 2-A: Then, subjects had to perform another block of rating (Rating 2-A). They had to rate the same destinations that has been rated
during Rating 1-A.
Choice 2-A: This Rating 2-A was followed by a new choice (Choice 2A). This time, subjects had to perform a choice between the other
40 destinations that had not showed during Choice 1-A. In the same
way, those destinations were coupled according to Rating 1-A.
• Part B:
Rating 1-B: This block followed the very same description that Rating
1-A block except that 80 new destinations were concerned.
Choice 1-B: This block followed the very same description than Choice
1-A, except that destinations were coupled according to Rating 1-B
block.
Manipulation A confederate appeared in the experimental room asking
the examiner for a urgent help to the examiner. The examiner accepted to go and help him but asked the confederate to stop put the
experiment on pause while he went and checked the problem. The
experimenter didn’t pause the experiment himself for two reasons:
first in pretending that it would gain time (while the experimenter
checked out the problem, the confederate paused the experiment),
second and more crucially in order to remain blind to the group the
subject was assigned to. In fact the real purpose of this cover story
was to allow the confederate to set a desktop background with one
of the quote categories (control-coherence- incoherence) that would
then stream on the screen for 3 minutes. There were 3 quotes per
category each appearing twice during 30 seconds. Once the quotes
were set, subjects were left in the room for 3 minutes. This design allowed a clear double blind whereby neither subjects not experimenter
17
knew which category the subjects were in. Only the confederate had
that information.
In each of the three categories (Coherence/Incoherence/Control) three
quotes were presented. These quotes were invented and they were
attributed to famous figures such as Einstein, Buddha and Socrates.
Therefore all three groups of subjects saw three quotes from these
three figures. The only difference was in the content of the quotes.
Coherence quotes praised coherence, incoherence quotes praised incoherence and control quotes were neutral and descriptive of poetry
and music.
Quotes used in the experiment
– For the Coherence group :
∗ ”La rigueur intellectuelle est la clé du succès.” Einstein
∗ ”La dignité n’existe que dans le respect de ses propres actions.” Socrates
∗ ”Le passé ne peut être changé, oublié, édité ou effacé. Tu te
dois de l’accepter.” Buddha
– For the Incoherence group :
∗ ”L’imbécile n’est pas celui qui a tort, mais celui qui refuse
de changer d’avis.” Einstein
∗ ”L’intelligence naı̂t de la contradiction.” Socrates
∗ ”Sois spontané et tu seras toi-même.” Buddha
– For the Control group :
∗ ”La musique est une mathématique sonore.” Einstein
∗ ”Un poème prend sens dans la voix du poète.” Socrates
∗ ”Ecoutez le vent comme vous écoutez la musique.” Buddha
Translation of the quotes in english
– For the Coherence group :
∗ ”Intellectual rigor is the key to success.” Einstein
∗ ”Dignity only exists in the respect of one’s own actions.”
Socrates
∗ ”Past can not be changed, forgotten, edited or erased. You
must accept it.” Buddha
– For the Incoherence group :
∗ ”The fool is not the wrong, but the one who refuse to change
his mind.” Einstein
∗ ”Intelligence stems from contradiction.” Socrates
∗ ”Be spontaneous and you will be yourself.” Buddha
– For the Control group :
∗ ”Music is sonorous mathematics.” Einstein
∗ ”A poem makes sense in the poet’s voice.” Socrates
∗ ”Listen to the wind as you listen to music.” Buddha
Rating 2-B: Then, subjects had to perform another block of rating (Rating 2-B). They had to rate the same destinations that has been rated
during Rating 1-B.
18
Choice 2-B This Rating 2-B was followed by a new choice (Choice 2B). This time, subjects had to perform a choice between the other
40 destinations that had not shown during Choice 1-B. In the same
way, those destinations were coupled according to Rating 1-B.
• Memory block: The subject was asked, for each destination if he has chosen it or rejected. Then, the subject was asked whether he was sure of
his answer. For both question, subjects had to answer manually using
the left/right keyboard arrows. As we were interested in testing whether
the subjects remembered the episode of the choice they made, we considered as remembered only the couples of destinations which had been both
correctly reported by the subject as chosen or rejected.
Statistical Method
According to our previous studies [Salti et al., 2014], choice-induced preference shows a strong correlation with memory that can be measured in the
interaction between the two factors Condition (RCR/RRC) and Memory (remembered, forgotten). As we mainly focused on this interaction, we tested the
effect of memory in this task using a linear mixed-effects model including the
spread for each pair of items for each subject, with the ‘Condition’ (RCR/RRC)
and the ‘Memory’ (remembered/forgotten) factors defined as fixed factors and
subjects defined as a random factor. Indeed, as opposed to a classical ANOVA,
such a model does not require prior averaging of the spread for each subject
and thus offer the possibility to handle the heteroskedasticity related to the unbalanced number of items in each condition [Baayen et al., 2008]. Significance
of the fixed effects was assessed using the Kenward-Roger approximation for
degrees of freedom of the denominator, with the ‘lmerTest’ package in R.
Selection
At the end of the experiment subjects filled a regret scale (translated from
Schwartz 2002) and then filled a debriefing form. They were asked whether they
had realized that the interruption was planned, or if he read the quotes, if he
could write them down, or if had felt any influence of those quotes on him. They
were also asked whether they had read the quotes and whether they felt that
the quotes had an influence on their behavior. They were then asked to write
the quotes such as they remembered them. In this experiment, we excluded
of the analysis of the Part B all subjects that reported being suspicious about
the interruption because this might mean that they were not influenced by the
quotes(4 subjects in the control group, 3 subjects in the coherence group, 4
subjects in the incoherence group). Moreover, in order to have a proper control
group, we excluded all participants that reported having felt an influence of the
citations in the Control group (5 subjects).
19
Figure 7: Figure showing spread of alternatives function of Condition,
Memory, Part, and Group.
3
3.1
Results
Manipulation of choice-induced preference change
Effect of manipulation
First of all, we tested the effect of manipulation. All subjects reported
having read the quotes. The interaction of the three factors ’Condition’, ’Memory’ and ’Group’ within the part B was significant (F(2,2259)=3.53, p=0.03).
Comparison between the Incoherence group and Control group was significant
(F(1,1426)=5.97, p=0.015), as well as comparison of the Incoherence group and
Coherence group (F(1,1545)=4.46, p=0.03). Comparison between Coherence
group and Control group was not significant (F(1,1546)=0.24, p=0.62). As we
can see in figure 7, The significant interaction between the groups Control and
Incoherence follows our prediction. Moreover, even if the interaction between
the groups Control and Coherence is not significant, we can see that the pattern
observed follows the direction of our predictions.
Restricted analysis in the remembered trials showed a significant interaction
of the factors ’Group’ and ’Condition’ (F(2,1166)=4.89, p=0.008). The same
analysis performed in the forgotten trials was not significant (F(2,1067)=0.28,
p=0.75).
Choice-induced preference change depends on memory of quotes
Furthermore, we made the prediction that the more subjects paid attention
to the quotes, the stronger the effect of the quotes, and the more subjects would
remember.
20
Figure 8: Figure showing spread of alternatives function of Condition,
Memory, Quotes, and Group for Control and Incoherence group.
In order to test this prediction, at the end of the experiment, we asked
subjects to write down the 3 quotes that appeared on the screen. We applied
the following criteria and created for each subject a quote-memory-score.
• 1 point if the quote was perfectly or almost perfectly remembered
• 0.5 point if some crucial words were remembered
• 0.25 point if only the author was remembered
• 0 point if nothing relevant was remembered
Our prediction was that if a group showed a difference in their interaction
of the factor ’Condition’ and ’Memory’ from the others group, this difference
should be correlated with the quote-memory-score.
Mean
1.58
Quote-memory-score descriptive statistics
Median
Standard Deviation
1.50
0.80
We wondered whether the differences between the different groups in their
interaction of the factors ’Condition’ and ’Memory’ could be interacting with
subjects’ memory of the quotes.
However, in order to prevent from potential confounds between the interaction of the factors ’Condition’ and ’Memory’ and the quote-memory-score due to
the episodic memory (Chammat and al. in prep), we performed a linear-model
to test to what extent the interaction of the factors ’Condition’ and ’Memory’
can be explained by the memory of quotes, controlling for the covariate ’Memory Performance’ (sum of remembered choices in Part B). First of all, the effect
of quotes was not significant in the Incoherence group (t= -1.179 , p=0.26).
However, we can notice that the tendency follows our predictions. The effect
was far from significance in the Control group (t= 0.094, p=0.93). In order
to perform a proper comparison of those effects, we performed the same test
21
but adding a factor group. Thus, we tested the interaction between the factor
’group’ and the effect of the memory of quotes on the interaction of the factors
’Condition’ and ’Memory’, controlling for the covariate ’Memory Performance’.
This test returned not significant (t= 1.17, p=0.25).
We assigned to each subject a new factor ’Quotes-memory’ (high/low) in
order to classify them as in the 1st half or in the 2nd half of the quote-memoryscore. See figure 8 We tested the interaction of the factors ’Condition’, ’Memory’, ’Group’, and ’Quotes-memory’ in the part B. This interaction was significant (F(1,2251)=3.16, p=0.04). Post-hoc analyses were done in order to identify
which groups were differing from the other in their interaction of the factors
’Memory’, ’Condition’ and ’Quotes’. Comparison between Incoherence group
and Control group was significant (F(1,1419)=5.96, p=0.015).Comparison between Control group and Coherence group was not significant (F(1,1541)=2.27,
p=0.13) as well as comparison between Incoherence group and Coherence group
(F(1,1541)=1.23, p=0.27).
At least, the Incoherence group and the Control group differed in their interaction between the factors ’Condition’, ’Memory’ and ’Quotes-memory’. Restricted analyses shows that, as expected, this interaction is significant within
the Incoherence group (F(1,710)=8.40, p=0.003), and is not within the Control
group (F(1,710)=0.25, p=0.61).
22
Figure 9: Figure showing spread of alternatives function of Condition,
Memory in the Part A across all-subjects
3.2
The choice-induced preference change in the control
condition (Part A)
First of all, we found a significantly larger spread in the RRC condition as
compared to 0 in the whole part A (t(72)=15.8, p¡10−25 ), which confirms the
artifact developed by Chen and Risen [Chen and Risen, 2010].
We also verified that the interaction of the factors ’Condition’ and ’Memory’
was not interacting with the factor ’Group’ in the control part of the experiment
(Part A). This interaction was unsignificant (F(2,2900)=0.58, p=0.56)
Then, we tested the quadruple interaction of the factors condition (RCR/RRC),
memory (remembered/forgotten), part (Part A/Part B) and group (group control/ group coherence/ group incoherence). This interaction was significant
(F(2, 4522)=4.15, p=0.015). We performed post-hoc ANOVA in order to identify which group were differing from the other groups in his interaction between
the factors ’Condition’, ’Memory’ and ’Part’. The comparison between the
Coherence group and the Control group was unsignificant (F(1,3100)=0.001,
p=0.97). However the comparison between Incoherence group and Control
group was significant (F(1,2848)=5.86, p=0.015) as well as the comparison
between Incoherence group and Coherence group (F(1,3096)=6.78, p=0.009).
We then performed restricted analyses in each group: the triple interaction of
the factors ’Condition’, ’Memory’ ’Part’ was unsignificant for the Coherence
group (F(1,1672)=1.59, p=0.20) and for the Control group (F(1,1426)=1.19,
p=0.27). However, this triple interaction was significant for the Incoherence
group (F(1,1422)=5.57 p=0.018).
Then, we pooled all groups together in order to test the existence of choice-
23
induced preference change in the absence of manipulation. We predicted that interaction of the factors ’Condition’ and ’Memory’ would be significant in the part
A, across all groups according to the literature [Salti et al., 2014]. On the contrary, this interaction across 72 subjects was not significant (F(1,2908.6)=0.477,
p=0.48). See Figure 9.
We hypothesized that the major difference between our experiment and
Salti’s experiment namely the delay between the second choice and the memory
test was at the origin of the absence of replication of Salti’s results.
According to the literature and to this hypothesis, we made two predictions.
First, that the interaction of interest should be present within the part B. Second, that subjects should have significantly less memory of the choices they
performed during the part A than memory of choices they performed during
during the part B.
All the tests that we performed earlier didn’t show any differences between
the two groups Coherence and Control. Thus, we decided to regroup these
two in order to have a better statistical power, that would lead to a better
understanding of the phenomenon.
We first tested the interaction across these two groups (n=39) of the factors
’Condition’ and ’Memory’. This interaction was significant (F(1,1550)=5.20,
p=0.023), according to the literature [Salti et al., 2014].
Secondly, we ran a t-test comparing the quantity of remembered pairs for
each subject in part A and in part B. This t t-test was significant (t(38)=-5.2297,
p ¡ 10−5 ).
In order to identify if our hypothesis was true, we developed several strategies.
24
1st Strategy : Compare subjects according to their memory performance
We regrouped all subjects and
calculated their memory performance (how many choices
they remembered correctly) across
the two conditions within the
part A (mean = 17.24, median=17, std=4.8442).
We
separated them in 4 quartiles according to their memory
performance (Q1=14, Q2=17,
Q3=21). Figure 10 shows the
spread function of ’Condition’
and ’Memory’ for each quartile. As we can see there is
a tendency for the spread in
the RCR condition to become
greater in comparison with the
RRC condition when subjects
have a better memory, and
this tendency seems to be even
more salient when we focus
on the items that were correctly remembered. In order
to test this tendency, we performed a global interaction of
the three factors ’Condition’,
’Memory’ and ’Quartiles’. This Figure 10: Spread of alternatives funcinteraction was unsignificant tion of Condition, Memory for each
(F(3,2900.27)=0.859, p=0.46). quartile in the part A
One-tailed comparison between
the 1st and the 4th quartile was close to significance (F(1.1430,87)=2.431,
p=0.055).
Nevertheless, this latter test strengthens our belief that the absence of interaction between the factors ’Condition’ and ’Memory’ was due to a memory
issue.
2nd Strategy : Simulation of forgetting
The next attempt to understand whether (decreased) memory was the cause of
this absence of interaction in the part A, was to simulate a progressive forgetting
from trials in part B.
In this simulation, we simulated the forgetting of certain choices (randomly).
We simulated that each subject would forget their choices incrementally. After this transformation, we calculated the interaction between the two factors
’Condition’ and ’Memory’. We did this procedure 5000 times for each point,
and calculated the proportion of iterations that showed a significant interaction
of the factors ’Condition’ and ’Memory’.
25
Figure 11: Simulation of significance of interaction of the factors ’Condition’ and ’Memory’ function of loss of memory
Figure 11 shows us that when subjects forget randomly the choice they
made, the interaction of the factors ’Condition’ and ’Memory’ progressively
looses significance. Moreover, we know that subjects had precisely 17.8 % less
memory of the part A than part B. If this loss of memory explained fully the
absence of interaction, we should see an important drop of significance at this
point (x=18). We find that f(18)=60.64, which means that, if subjects loose
18% of memory, we will find 40% less times the interaction of interest, if we
make the hypothesis that our dataset is representative of the phenomenon.
This give us another argument to think that memory could be the cause of
the phenomenon we are trying to understand. But this simulation has a main
limit, that is that it is unlikely that every choices have the same probability to
be forgotten. This limit leads us to the next strategy.
3rd Strategy : Dissociating the impact of forgetting according to
ratings difference (R2-R1)
Another strategy is to wonder whether some choices that have been made are
more likely to be forgotten than others. As far as there is no significant differences between the spread observed in the two conditions RCR and the RRC
condition remembered (t(38)=0.39, p=0.69), which is also not in accordance
with the literature, it is likely to think that choices that led to a big change in
preference have been more forgotten than others.
In this section, we are not dealing anymore with the spread that has been
created between two ratings in accordance with the choice corresponding, but
we are dealing with the difference between the two ratings for one given item.
The question that we want to answer in this section is the following : do
subjects forget the choices they made on some items more than other items, and
if so, can this forgetting explain the reason of the lack of replication of what is
observed in the literature ?
We performed a Kolmogorov-Smirnov test on the distributions of difference
between Rating 2 and Rating 1 for each item in the RCR remembered condition,
and compared the distributions in the Part A and the distribution in the part
B. This test was significant (D=0.0677, p=0.01375), whereas the same test
performed on the RRC remembered was not significant (D=0.0325, p=0.5734).
26
Figure 12: Proportion of items remembered function of the Rating 2
minus Rating 1 in the RCR condition
Those two tests argue in the favor of the hypothesis that choices made in
the RCR condition are not kept in memory (and forgotten) in the same way
than items in the RRC condition.
We can see in Figure 12 that our prediction that some high Rating 2 minus
Rating 1 in absolute value should be more forgotten in part A than in part B
was true. More specifically, this phenomenon concerns simply items for which
Rating 2 was superior to rating 1.
This argument strongly strengthens the idea that the subjects do not show
the interaction of the factors ’Condition’ and ’Memory’ because of a specific forgetting of the choices made on items that produced a choice-induced preference
change, while performing the Memory task.
4th Strategy : combine the 2nd strategy and the 3rd strategy
As it has been said before, a major criticism of the 2nd strategy is that we
simulate the forgetting randomly. The 3rd strategy showed us that some the
choices made on some items are more specifically remembered, and others are
more specifically forgotten.
In this last strategy, we simulated the forgetting of the subjects regarding
the change in ratings of the items we are considering. In other words, for the
RCR condition, we made the subjects preferentially forget the items that had a
positive Rating 2 minus Rating 1, then the items that had a null Rating 2minus
Rating 1, and finally, the items that had a negative Rating 2 minus Rating
1. Whereas, for the RRC condition, we made the subjects forget the items
regardless of their change in ratings.
Figure 13 shows that the significance of the interaction of the factors ’Condition’ and ’Memory’ drops drastically. Moreover, we see that this new simulation
27
Figure 13: Simulation of significance of interaction of the factors
’Condition’ and ’Memory’ function of forgetting. In this new simulation (red curve), positive RCR remembered are forgotten prioritarily, whereas
RRC remembered are forgotten randomly. Blue curve corresponds to the first
simulation
(red curve) decreases the significance of the interaction in a stronger way than
the first simulation (blue curve).
The comparison of those two simulations is an argument to support the
idea that the non significance of the interaction of the factors ’Condition’ and
’Memory’ in the control part (Part A) was due to the specific forgetting of the
choices.
28
4
Discussion
In this study we explore several aspects of choice-induced preference change in
the free-choice paradigm.
Synthesis
First of all, we replicated the existence of the artifact described by Chen
and Risen [Chen and Risen, 2010]. Indeed, spreads in the RRC condition were
systematically significantly larger than 0.
Our results also replicated the results obtained by Salti et al. [Salti et al., 2014]
namely that : a genuine choice-induced preference change effect is exclusively
found for remembered items.
However, the main result of the present study is that rather than being
automatic choice-induced preference change can be modulated by an external
factor: quotes. Moreover, the influence of these quotes on subjects’ behavior
went in the predicted direction : suggestion of the ”Incoherence” significantly
decreased the choice-induced preference change, whereas the reverse effect was
observed with the ”Coherent” suggestion. As detailed later, this suggestibility effect seemed to be mostly driven by the results of the Incoherence group
in which choice induced preference change seems to be canceled. Our results
therefore demonstrate that choice-induced preference change is suggestible.
We also discovered that this effect was strongly related to the memory of
the quotes. Therefore, and in sharp contrast with automatic theories of choiceinduced preference change, we show here that there are at least two modes of
choice-induced preference change modulation exerted through episodic memory: memory of previous choices, as well as memory of the current contextual
influence mediated by the quotes.
Finally, we found that subjects tend to forget more items associated with an
increase of ratings (R2-R1) than items with a reverse profile. This last result
is reminiscent of loss aversion effects previously reported in the field of decision
making [Tversky and Kahneman, 1991].
Mechanism of the manipulation
We showed that choice-induced preference change effect depends on several
top-down effects. Some have an internal source, such as episodic memory, or an
external source, such as external quotes.
However, the precise role of the memory is difficult to interpret. First,
episodic memory seems to correlate with the spread as it is represented by the
significant main effect of memory (p ¡ 10− 7). The higher spread in the RRC
remembered condition reflects this correlation between memory and spread.
However, Chammat and al. (in prep.) are currently reporting the necessary
role of memory of the choice in the choice-induced preference change effect.
In other terms, unlike the RRC remembered condition, the RCR remembered
condition captures two phenomena : the correlation of the spread with memory
and the necessity of memory on choice-induced preference change.
Nevertheless, in spite of this complex role of memory, the results show that
choice-induced preference change has been canceled in the Incoherence group,
which demonstrate that choice-induced preference change is suggestible.
29
A manipulation that correlates with the memory of quotes
Our next result brings supplementary evidence in support of choice-induced
preference change being a suggestible phenomenon.
Indeed, we found that the influence of the quotes depended on the memory
of the quotes. In other words, it seems that memory of the current contextual
influence mediated choice-induced preference change effects.
However, the interpretation of this result requires an understanding of the
underlying mechanisms. Indeed, according to other studies that we are currently
working on (Chammat and al, in prep), memory has a causal role in choiceinduced preference change. In other words, during the second rating, subjects
have to remember the choice they made in order to show a choice-induced preference change. According to this idea, if a subject has a good memory, on the
one hand, he should show a greater interaction of the factors ’Condition’ and
’Memory’ (we can see that this is the tendency in the 1st strategy of 3.2), and
on the other hand, he should remember better the citations that appeared on
the screen. Thus, it might not be the memory of the citations that influences
the interaction, but the global memory that correlates with the memory of the
citations and the interaction of the factors ’Condition’ and ’Memory’.
In trying to understand the effect of memory of the quotes on choice-induced
preference change (CIPC), two contradictory hypothesis can be made. First, one
can make the hypothesis that in the incoherence group subjects that have the
best memory of quotes should show a smaller choice-induced preference change
effect, because of the influence of the quotes. Second one can hypothesize that
these subjects should show a greater choice- induced preference change because
they have a better memory which would in turn lead to a greater choice-induced
preference change effect. In an effort to test these hypotheses we compared the
incoherence and control groups by looking at the Influence of memory of quotes
on CIPC. Our results show that indeed that influence of memory of quotes on
CIPC is significantly higher in the incoherence group as compared to the control
group.
Taken together, these results strengthen the idea that choice-induced preference change is not an automatic process. Indeed, according to models postulating automatic updating of values, the spread should not be affected by
such external simple sentences. More specifically, we show that choice-induced
preference change depends on one’s own tendency to be coherent and that this
tendency is suggestible. More precisely, we demonstrate that the focused attention on this influence correlates with the magnitude of this influence.
Asymmetric importance of choosing or rejecting items
Part A of our experiment showed a pattern of results that is different from
the classical results found in the literature ([Salti et al., 2014], Chammat and
al (in prep.) etc.). In order to understand this difference we hypothesized that
it might by caused by the longer than usual interval between the second choice
and the memory test compared to these other studies but also to part B’s of our
experiment. In order to find arguments validating or refuting this hypothesis,
we developed several strategies. First, we saw that there is a tendency for best
memory performers to show a greater interaction of the factors ’Condition’ and
’Memory’ in the predicted way. In other words the time interval might have
indeed affected this difference of pattern. Second, we simulated an incremental
forgetting of the choices. In other words we simulated situations in which sub30
jects would forget more and more choices. This simulation makes the interaction
of the ’Condition’ and ’Memory’ factors progressively less significant. Third, we
tried to identify the items that were specifically remembered. We found that
items that were under-rated during rating 2 compared to rating 1 were prone to
be better memorized. Finally, we ran a new simulation showing that forgetting
specifically the choices made on those items decreases the significance of the
interaction of the factors ’Condition’ and ’Memory’ even more than forgetting
the choices randomly.
These results reveals an asymmetry of the memory trace of the choice and
supports the theory of loss aversion. Indeed, it might be possible that subjects
better memorized the items that they rejected (these are the items that have a
lower rating 2 compared to rating 1) due to the loss aversion bias. Indeed loss
aversion refers to people’s tendency to strongly prefer avoiding losses to acquiring gains. [Tversky and Kahneman, 1991].The central assumption of the theory
is that losses and disadvantages have greater impact on preferences than gains
and advantages. A wide array of studies of human judgment and decision making indicate that avoiding loss carries greater psychological impact than attaining an equivalent gain ([Dreher, 2007] [Tversky and Kahneman, 1981]]. Additionally, processing losses is linked to differential brain activity relative to attaining gains ([Knutson et al., 2000]; [Pessiglione et al., 2006];[Wheeler and Fellows, 2008]).
A recent study has also found that memory was enhanced for loss-threatening
incentives as compared to opposite [Krawczyk and D’Esposito, 2013]
Nature of the choice-induced preference change
Another related question concerns the nature of the preference change effect. First is this mechanism low-level or high-level mechanism? Also, is CIPC
driven by the inconsistency of choices? Indeed, according to models claiming for
an automatic low-level updating of values, if the preference change effect was
exclusively driven by the inconsistency of the choice, the encoding of new values
in one’s value system should occur automatically after the choice. If this hypothesis were correct, and that subjects automatically modify their preferences
after the choice then our manipulation (which occurs after the choice is made)
should not have any impact on any of the subjects’ behavior. However our results show an impact of the manipulation and therefore are not in accordance
with these models. On the contrary they tend to support models suggesting
that the choice-induced preference change effect depends on high-level cognitive functions such as executive control and episodic memory. However within
this high-level process subjects might have behaved in two different ways. First
subjects might have changed their preference during the first choice such as predicted by Festinger’s model of cognitive dissonance theory. And in this case our
manipulation might have influenced subjects’ value updating a posteriori. Alternatively it is argued that the genuine mechanism occurring in the free-choice
paradigm might be simple tendency for consistency between present and past
action. Therefore in our experiment we might have influenced this tendency for
consistency. Accordingly, when subjects perform their Rating 2 following the
choice, they would seek to be as coherent as possible with the choice they just
made. Our results support both of these possibilities and further studies would
be needed in order to distinguish between them.
More generally our results are in accordance with Chammat and al. (in prep)
which shows the engagement of the hippocampus during the second rating. We
31
have therefore gathered lines of evidence in support of choice-induced preference
change being a high-level process and that this change in preference is more
likely to occur during Rating 2 than during the Choice.
5
General Conclusion and Perspectives
In conclusion our experiment adds a new property to choice-induced preference
change which is that this phenomenon is prone to external influence and therefore non-automatic. Since its initial formalization several findings show that this
phenomenon is more complex than previously thought. Firstly, it depends on
the availability of the information about the choice, secondly, it depends on executive control, thirdly, it is suggestible by conscious influences. These properties
share strong links with consciousness. Once could perhaps draw the following
analogy : since all of these properties share a strong link with consciousness,
this must mean that the subject is conscious of this phenomenon. This analogy would however be wrong. Indeed, most subjects do not report having been
coherent with (or influenced by) their choice. This mismatch between subjects
metacognition of this phenomenon and the high-level cognitive processes that
it engages calls for future studies to further characterize this mechanism and its
links with consciousness.
References
[Aronson, 1968] Aronson, E. (1968). Dissonance theory: Progress and problems.
[Baayen et al., 2008] Baayen, R. H., Davidson, D. J., and Bates, D. M. (2008).
Mixed-effects modeling with crossed random effects for subjects and items.
Journal of memory and language, 59(4):390–412.
[Bargh et al., 1996] Bargh, J. A., Chen, M., and Burrows, L. (1996). Automaticity of social behavior: Direct effects of trait construct and stereotype
activation on action. Journal of personality and social psychology, 71(2):230.
[Bem, 1973] Bem, D. J. (1973). Self-perception theory1.
[Brehm, 1956] Brehm, J. W. (1956). Postdecision changes in the desirability of
alternatives. The Journal of Abnormal and Social Psychology, 52(3):384–389.
[Chen and Risen, 2010] Chen, M. K. and Risen, J. L. (2010). How choice affects and reflects preferences: Revisiting the free-choice paradigm. Journal of
Personality and Social Psychology, 99(4):573.
[Cheryan and Bodenhausen, 2000] Cheryan, S. and Bodenhausen, G. V. (2000).
When positive stereotypes threaten intellectual performance: The psychological hazards of “model minority” status. Psychological Science, 11(5):399–402.
[Cooper, 2007] Cooper, J. (2007). Cognitive dissonance: 50 years of a classic
theory. Sage.
[Dreher, 2007] Dreher, J.-C. (2007). Sensitivity of the brain to loss aversion
during risky gambles. Trends in cognitive sciences, 11(7):270–272.
32
[Egan et al., 2007] Egan, L. C., Santos, L. R., and Bloom, P. (2007). The origins
of cognitive dissonance evidence from children and monkeys. Psychological
science, 18(11):978–983.
[Festinger, 1957] Festinger, L. (1957). A theory of cognitive dissonance, volume 2. Stanford university press.
[Izuma et al., 2010] Izuma, K., Matsumoto, M., Murayama, K., Samejima, K.,
Sadato, N., and Matsumoto, K. (2010). Neural correlates of cognitive dissonance and choice-induced preference change. Proceedings of the National
Academy of Sciences, 107(51):22014–22019.
[Knutson et al., 2000] Knutson, B., Westdorp, A., Kaiser, E., and Hommer, D.
(2000). Fmri visualization of brain activity during a monetary incentive delay
task. Neuroimage, 12(1):20–27.
[Krawczyk and D’Esposito, 2013] Krawczyk, D. C. and D’Esposito, M. (2013).
Modulation of working memory function by motivation through loss-aversion.
Human brain mapping, 34(4):762–774.
[Kuzyakov et al., 2000] Kuzyakov, Y., Friedel, J., and Stahr, K. (2000). Review of mechanisms and quantification of priming effects. Soil Biology and
Biochemistry, 32(11):1485–1498.
[Lieberman et al., 2001] Lieberman, M. D., Ochsner, K. N., Gilbert, D. T., and
Schacter, D. L. (2001). Do amnesics exhibit cognitive dissonance reduction?
the role of explicit memory and attention in attitude change. Psychological
Science, 12(2):135–140.
[Nelson and Norton, 2005] Nelson, L. D. and Norton, M. I. (2005). From student to superhero: Situational primes shape future helping. Journal of experimental social psychology, 41(4):423–430.
[Pessiglione et al., 2006] Pessiglione, M., Seymour, B., Flandin, G., Dolan,
R. J., and Frith, C. D. (2006). Dopamine-dependent prediction errors underpin reward-seeking behaviour in humans. Nature, 442(7106):1042–1045.
[Salti et al., 2014] Salti, M., Karoui, I. E., Maillet, M., and Naccache, L. (2014).
Cognitive dissonance resolution is related to episodic memory. PLoS ONE,
9(9):1–8.
[Schwarz and Büchel, 2015] Schwarz, K. A. and Büchel, C. (2015). Cognition
and the placebo effect–dissociating subjective perception and actual performance. PloS one, 10(7):e0130492.
[Schwarz et al., 2016] Schwarz, K. A., Pfister, R., and Büchel, C. (2016). Rethinking explicit expectations: Connecting placebos, social cognition, and
contextual perception. Trends in cognitive sciences, 20(6):469–480.
[Sharot et al., 2009] Sharot, T., De Martino, B., and Dolan, R. J. (2009). How
choice reveals and shapes expected hedonic outcome. The Journal of Neuroscience, 29(12):3760–3765.
33
[Sharot et al., 2012] Sharot, T., Fleming, S. M., Yu, X., Koster, R., and Dolan,
R. J. (2012). Is choice-induced preference change long lasting? Psychological
science, 23(10):1123–1129.
[Steele, 1988] Steele, C. M. (1988). The psychology of self-affirmation: Sustaining the integrity of the self. Advances in experimental social psychology,
21(2):261–302.
[Steele and Aronson, 1995] Steele, C. M. and Aronson, J. (1995). Stereotype
threat and the intellectual test performance of african americans. Journal of
personality and social psychology, 69(5):797.
[Tversky and Kahneman, 1974] Tversky, A. and Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. science, 185(4157):1124–1131.
[Tversky and Kahneman, 1981] Tversky, A. and Kahneman, D. (1981). The
framing of decisions and the psychology of choice. Science, 211(4481):453–
458.
[Tversky and Kahneman, 1991] Tversky, A. and Kahneman, D. (1991). Loss
aversion in riskless choice: A reference-dependent model. The quarterly journal of economics, pages 1039–1061.
[Van Veen et al., 2009] Van Veen, V., Krug, M. K., Schooler, J. W., and Carter,
C. S. (2009). Neural activity predicts attitude change in cognitive dissonance.
Nature neuroscience, 12(11):1469–1474.
[Wheeler and Fellows, 2008] Wheeler, E. Z. and Fellows, L. K. (2008). The human ventromedial frontal lobe is critical for learning from negative feedback.
Brain, 131(5):1323–1331.
34
Figure 14: Simulation of t-test on
the dataset function of number of
choices
Figure 15: Simulation of interaction
on the dataset function of number of
choices
Appendix
Preliminary simulation
As we didn’t want to make the experiment twice longer than it was in our
latest version of the free-choice paradigm [Salti et al., 2014], we ran simulations
on data of previous experiment (Chammat and al. in prep). The purpose of
those simulations were to modelize the power of each part with even with less
trials per block. We made the hypothesis that our data were representative of
the phenomenon in the global population. Thus, with enough participants, the
power of our experiment should be predicted by this simulation. As we wanted
to decrease the number of trials per block, we constructed a graph representing
how many times the main interaction (condition and memory) and the main
t-test (spread in the RCR condition versus RRC condition for the choice that
were remembered) would be significant in function of the number of trials per
’Choice’ block. (See figure 14 and 15) Since the power of the statistic tests drop
drastically function of the number of choices, we made the decision to keep 20
choices per block of choices instead of 25 as it was before, in order to make the
experiment have an acceptable duration and not to loose too much statistical
power.
35
Manipulation Stimuli
36
Figure 16: Stimuli used as desktop background in order to influence subjects’
coherence tendency for the Coherence and the Incoherence. The quotes were
supposed not to influence subjects’ coherence tendency in the Control group
37