DOCUMENTS

Mertens, G., Raes, A. K., & De Houwer, J. (In press). Can prepared fear conditioning result from verbal instructions? Learning and Motivation.

Evolutionary fear-relevant stimuli such as snakes or spiders are thought to be prepared to elicit fear reactions. This implies that the acquisition of conditioned fear responses is facilitated when these stimuli serve as conditioned stimuli (CSs). Moreover, extinction of conditioned fear responses is delayed when CSs are prepared stimuli. The research presented in this article addresses the question whether such selective learning effects can be obtained even when participants do not experience pairings of CSs and US but receive only instructions about those pairings. Two experiments were conducted in which participants were verbally informed about the relationship between fear-relevant and fear-irrelevant CSs and the presence of an electrical stimulus (US). However, CSs were never actually paired with the US. US expectancy ratings and skin conductance responses were recorded during multiple CS only trials. In the first experiment, we observed acquisition, extinction and reinstatement of fear on the basis of instructions, but these effects were not modulated by the fear-relevance of the CSs. In the second experiment, we manipulated whether participants actually experienced the CS-US contingencies or were merely instructed. We obtained facilitated acquisition for the merely instructed fear-relevant CS+. We discuss these results in relation to the evolutionary fear learning model of Öhman and Mineka (2001) and the expectancy bias model of Davey (1992).

The ability to follow new instructions is crucial for acquiring behaviors and the cultural
transmission of performance-related knowledge. In this article, we discuss the observation
that successful instruction following seems to require both the capacity to understand verbal
information, but also the ability to transform this information into a procedural format. Here
we review the behavioural and neuroimaging literature on following new instructions and
discuss how it contributes to our understanding of the functional mechanisms underlying
instruction following. Based on this review, we distinguish three phases of instruction
following. In the instruction phase, the declarative information of the task instruction is
transformed into a task model consisting of a structured representation of the relevant
condition-action rules. In the implementation phase, elements of this task model are
transformed into a highly accessible state guiding behaviour. In the application phase, the
relevant condition-action rules are applied. We discuss the boundary conditions and capacity
limits of these phases, determine their neural correlates, and relate them to recent models
of working memory.

Unlike other animals, humans have the unique ability to share and use verbal instructions to prepare
for upcoming tasks. Recent research showed that instructions are sufficient for the automatic, reflexlike activation of responses. However, systematic studies into the limits of these automatic effects of
task instructions remain relatively scarce. In this study, we set out to investigate whether this
instruction-based automatic activation of responses can be context-dependent. Specifically,
participants performed a task of which the stimulus-response rules and context (location on the screen)
could either coincide or not with those of an instructed to-be-performed task (whose instructions
changed every run). In two experiments, we showed that the instructed task rules had an automatic
impact on performance – performance was slowed down when the merely instructed task rules did not
coincide, but, importantly, this effect was not context-dependent. Interestingly, a third and fourth
experiment suggests that context dependency can actually be observed, but only when practicing the
task in its appropriate context for over sixty trials or after a sufficient amount of practice on a fixed
context (the context was the same for all instructed tasks). Together, these findings seem to suggest
that instructions can establish stimulus-response representations that have a reflexive impact on
behavior, but are insensitive to the context in which the task is known to be valid. Instead, contextspecific task representations seem to require practice.

Learning fear via the experience of contingencies between a conditioned stimulus (CS) and an
aversive unconditioned stimulus (US) is often assumed to be fundamentally different from
learning fear via instructions. An open question is whether fear-related brain areas respond
differently to experienced CS-US contingencies than to merely instructed CS-US contingencies.
Here, we contrasted two experimental conditions where subjects were instructed to expect the
same CS-US contingencies while only one condition was characterized by prior experience with
the CS-US contingency. Using multi-voxel pattern analysis of fMRI data, we found CS-related
neural activation patterns in the right amygdala (but not in other fear-related regions) that
dissociated between whether a CS-US contingency had been instructed and experienced versus
merely instructed. A second experiment further corroborated this finding by showing a
category-independent neural response to instructed and experienced, but not merely instructed,
CS presentations in the human right amygdala. Together, these findings are in line with
previous studies showing that verbal fear instructions have a strong impact on both brain and
behaviour. However, even in the face of fear instructions, the human right amygdala still shows
a separable neural pattern response to experience-based fear contingencies.

Van Dessel, P., De Houwer, J., & Gast, A. (2016). Approach-avoidance training effects are moderated by awareness of stimulus-action contingencies. Personality and Social Psychology Bulletin, 42, 81-93.

Prior research suggests that repeatedly approaching or avoiding a stimulus changes the liking of
that stimulus. In two experiments, we investigated the relationship between, on the one hand,
effects of approach-avoidance (AA) training on implicit and explicit evaluations of novel faces
and, on the other hand, contingency awareness as indexed by participants’ memory for the
relation between stimulus and action. We observed stronger effects for faces that were classified
as contingency aware and found no evidence that AA training caused changes in stimulus
evaluations in the absence of contingency awareness. These findings challenge the standard view
that AA training effects are (exclusively) the product of implicit learning processes, such as the
automatic formation of associations in memory.