A Conceptual and Theoretical Analysis of Evaluative Conditioning
Evaluative conditioning is best defined as an effect, that is, as a change in the valence of a stimulus
that results from pairing the stimulus with another stimulus. This definition has several advantages
that are made explicit in this paper. One of the advantages is that it clarifies that evaluative
conditioning can be due to multiple processes. Therefore, the conditions under which evaluative
conditioning is observed can depend on the processes that underlie a particular manifestation of
evaluative conditioning. This could explain why there are so many conflicting results about the
conditions under which evaluative conditioning can be found. Future research should adopt a
meta-conditional approach that focuses not only on whether a certain condition is crucial for
obtaining evaluative conditioning but should also examine when a certain condition is crucial.
The preparation of this paper was made possible by Grant BOF/GOA2006/001 of Ghent University.
I thank the SEPC (Sociedad Española de Psicología Comparada -Spanish Society of Comparative Psychology-) for inviting me to
write this paper. I dedicate this paper to my mentor, Paul Eelen, who introduced me to evaluative conditioning, to the distinction between
procedure, effect, and theory, and to good food and drinks, to name just a few things. I benefited greatly from many discussions with
Agnes Moors regarding the concepts “automaticity” and “functional characteristics.” Many thanks also to Tom Beckers and Agnes Moors
for their comments on a first draft of this paper.
One of the most influential ideas in psychology is that
preferences are an important determinant of behavior (e.g.,
Allport, 1935; Martin & Levy, 1978). To give just a few
examples from daily life, people tend to seek the company
of persons they like and avoid being in the company of
persons they do not like; they buy products that they like
more often than those that they do not like; people vote for
the politicians that they find sympathetic but not those that
repel them; they will pay to do the things they like but need
to be paid to do the things that they dislike. Furthermore,
preferences influence attention, memory, and judgments,
and form the basis of our emotional life. In order to
understand, predict, and influence behavior, it is thus crucial
to understand how preferences are formed and can be
influenced. Evaluative conditioning is generally considered
to be one of the approaches to influence liking. Studies on
evaluative conditioning have shown that the liking of a
neutral stimulus can be changed by pairing it with another,
liked or disliked, stimulus. The first stimulus is often called
the conditioned stimulus or CS whereas the second stimulus
is often called the unconditioned stimulus or US. Typically,
a CS will become more positive when it has been paired
with a positive US than when it has been paired with a
negative US. Well known real-life examples of evaluative
conditioning are the “have-a-Coke-and-a-smile” ads of the
Coca-Cola Company. In these ads, the Coke brand name
(CS) is repeatedly presented together with images of smiling
people having fun (US). It is assumed that this will increase
the liking of the brand.
Evaluative conditioning has been examined in a large
number of studies (see De Houwer, Thomas, & Baeyens,
2001, for an extensive review, and De Houwer, Baeyens, &
Field, 2005, for an update). Nevertheless, our understanding
of the phenomenon is still very limited. There now is general
agreement about the fact that evaluative conditioning is a
genuine phenomenon (an agreement that has been reached
only recently; see De Houwer, Baeyens, et al., 2005). It also
seems safe to conclude that evaluative conditioning can be
found with various kinds of stimuli and procedures. At the
same time, genuine failures to find evaluative conditioning
suggest that certain boundary conditions need to be fulfilled
before evaluative conditioning can emerge (see De Houwer
et al., 2001, for a review). There is little else that evaluative
conditioning researchers agree about. For instance, whereas
some results suggest that the effect can be found even when
participants are not aware of the CS-US contingencies (e.g.,
Baeyens, Eelen, & Van den Bergh, 1990; Dickinson &
Brown, 2007), the results of other studies suggest that
evaluative conditioning does crucially depend on contingency
awareness (e.g., Pleyers, Corneille, Luminet, & Yzerbyt,
2007). Likewise, whereas some argue that evaluative
conditioning is unaffected by extinction (i.e., presentations
of the CS in isolation after the CS-US pairings; e.g.,
Baeyens, Crombez, Van den Bergh, & Eelen, 1988; Diaz,
Ruis, & Baeyens, 2005), others have reported data showing that extinction does affect evaluative conditioning (e.g.,
Lipp, Oughton, & LeLievre, 2003).
In the current paper, I present a conceptual and
theoretical analysis that clarifies why so little progress has
been made in the study of evaluative conditioning and how
this can be remedied in future research. I will first argue
that evaluative conditioning is best defined as an effect rather
than as a specific procedure or theoretical process. This
conceptual analysis has important theoretical implications.
When defined as an effect, it becomes clear that different
kinds of processes could produce evaluative conditioning
effects (also see De Houwer, Baeyens, et al., 2005). This
insight sheds new light on many contradictory findings that
have been reported in the literature. It also implies that future
research should not only test whether a certain condition is
crucial for obtaining evaluative conditioning but should also
examine when a certain condition is crucial.
A Conceptual Analysis
The Distinction between Procedure, Effect, and Theory
The starting point of the present analysis is the distinction
between procedure, effect, and theory (see Bolles, 1979;
Eelen, 1980). Before applying this distinction to the concept
“evaluative conditioning,” I will try to explain the distinction
and illustrate it with regard to the well known concept
“priming”. A procedure is simply an objective list of actions,
a set of guidelines about what to do. It specifies the manner
in and conditions under which stimuli are presented and
responses registered. For example, a priming procedure most
often involves: (a) presenting on each trial a prime stimulus
and a target stimulus that are either related (e.g., NURSEDOCTOR)
or unrelated (e.g., WALL-DOCTOR) and (b)
registering how long participants need to respond to the
target. An effect, on the other hand, is the result of a
procedure. More specifically, it is an observation that is
attributed to a certain abstract, core feature of the procedure.
For instance, the observation in priming tasks that responses
to the target DOCTOR are fast when it is preceded by the
prime NURSE can be labeled a priming effect if this
observation is attributed to the relatedness of the prime and
target. The core feature “relatedness” is abstract in that it
applies to a range of stimuli under a variety of conditions.
An observation becomes an effect only when there is
evidence showing that the core element of the procedure is
responsible for the observation. In the case of a priming
effect, this implies comparing reaction times on trials with
related prime-target pairs to reaction times on trials with
equivalent prime-target pairs that are not related in the same
manner. In practice, using the term effect thus requires a
comparison of observations in situations that differ only
with regard to the core procedural element that is thought
to be crucial for the effect. Finally, the term theory can be understood in this context as referring to the theoretical
processes that are assumed to be responsible for an effect.
For example, priming effects are often attributed to activation
that spreads in a semantic network from the representation
of the prime to the representation of the target, thus
facilitating responses to the target. A theory therefore implies
not only that a certain observation is due to a core element
of a procedure (e.g., relatedness of prime an target), it also
makes assumptions about the processes by which the core
elements of the procedure lead to the observed behavior
(e.g., spreading of activation).
Because concepts can be used to refer to a procedure,
effect, or theoretical process, it is important to always make
explicit the manner in which a term is used. For instance,
saying that NURSE primes DOCTOR can mean that the
word NURSE is presented briefly before the word DOCTOR
(priming as a procedure), that the presentation of NURSE
speeds up responses to DOCTOR because the two words
are related (priming as an effect), or that NURSE speeds
up responses to the related word DOCTOR because
activation spreads from the representation of the concept
“nurse” to the representation of the concept “doctor”
(priming as a theoretical process). To avoid confusion, one
needs to clarify which of the three meanings is appropriate
Applying the Distinction between Procedure, Effect,
and Theory to Evaluative Conditioning
Like the concept “priming,” the concept “evaluative
conditioning” can be used to refer to a procedure, an effect,
or a theoretical process. Let us return to the example of the
“have-a- Coke-and-a-smile” ads. To say that this is an
example of evaluative conditioning can mean several things.
First, it could imply that the marketeers behind the ad
campaign used a certain procedure that is in essence identical
to the procedure used in evaluative conditioning studies.
Both in the ads and in lab studies, stimuli (e.g., a brand
name and pictures of smiling people) are presented together
in a certain manner and it is ass