De Houwer, J. (2014). A Propositional Model of Implicit Evaluation. Social and Personality Psychology Compass, 8, 342-353.
Implicit evaluation can be defined as the automatic effect of stimuli on evaluative responses. A major advantage of this definition is that it is neutral with regard to the mental processes and representations that mediate implicit evaluation. Whereas many existing models postulate that implicit evaluation is mediated by the automatic spreading of activation along associations in memory, it is also possible to entertain the idea that implicit evaluation is due to the automatic formation or activation of propositions. In line with such a propositional model of implicit evaluation, evidence suggests that implicit evaluation (a) can be based on instructions and inferences, (b) is sensitive to information about how stimuli are related, and (c) can reflect several propositions that differ only with regard to how stimuli are related. Although it might be difficult to differentiate between propositional models on the one hand and association-activation or dual-process models on the other hand, merely considering the idea that implicit evaluation might be mediated by propositions offers a new perspective on existing findings and leads to novel predictions about the conditions under which implicit evaluation occurs.
Raes, A. K., De Houwer, J., De Schryver, M., Brass, M., & Kalisch, R. (2014). Do CS-US pairings actually matter? A within-subject comparison of instructed fear conditioning with and without actual CS-US pairings. PLoS ONE 9(1): e84888. doi:10.1371/journal.pone.0084888
Previous research showed that instructions about CS-US pairings can lead to fear of the CS even when the pairings are never presented.In the present study, we examined whether the experience of CS-US pairings adds to the effect of instructions by comparing instructed conditioning with and without actual CS-US pairings in a within-subject design. Thirty-two participants saw three fractals as CSs (CS+1, CS+2, CS-) and received electric shocks as USs. Before the start of a so-called training phase, participants were instructed that both CS+1 and CS+2 would be followed by the US, but only CS+1 was actually paired with the US. The absence of the US after CS+2 was explained in such a way that participants would not doubt the instructions about the CS+2-US relation. After the training phase, a test phase was carried out. In this phase, participants expected the US after both CS+s but none of the CS+s was actually paired with the US. During test, self-reported fear was initially higher for CS+1 than for CS+2, which indicates that the experience of actual CS-US pairings adds to instructions about these pairings. On the other hand, the CS+s elicited similar skin conductance responses and US expectancies. Theoretical and clinical implications are discussed.
Van Dessel, P. , De Houwer, J., Roets, A., & Gast, A. (2016). Failures to change stimulus evaluations by means of subliminal approach and avoidance training. Journal of Social and Personality Psychology, 110, e1-e15.
Previous research suggests that the repeated performance of approach and avoidance (AA) actions in response to a stimulus causes changes in stimulus evaluations. Kawakami, Phills, Steele, and Dovidio (2007) and Jones, Vilensky, Vasey, and Fazio (2013) provided evidence that these AA training effects occur even when stimuli are presented only subliminally. We also examined whether reliable AA training effects can be observed with subliminal stimulus presentations but added more sensitive checks of perceptual stimulus discriminability. Three experiments, including a direct replication of the study by Kawakami et al. (2007), failed to provide any evidence for effects of subliminal AA training on implicit or explicit evaluations. Bayesian analyses indicated that our data provide robust evidence that subliminal AA training does not cause changes in evaluations. In contrast, we observed changes in evaluations when participants were provided with (either correct or incorrect) information about the stimulus-action contingencies in the subliminal AA training task and when participants performed a supraliminal AA training task that allowed participants to detect these contingencies. These findings support the idea that contingency awareness is necessary for the occurrence of AA training effects.
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.
Mertens, G., Kuhn, M., Raes, A. K., Kalisch, R., De Houwer, J., & Lonsdorf, T. B. (In press). Fear expression and the return of fear following threat instruction with or without direct contingency experience. Cognition and Emotion.
Prior research showed that mere instructions about the contingency between a Conditioned Stimulus (CS) and an Unconditioned Stimulus (US) can generate fear reactions to the CS. Little is known, however, about the extent to which actual CS-US contingency experience adds anything beyond the effect of contingency instructions. Our results extend previous studies on this topic in that it included fear potentiated startle as an additional dependent variable and examined return of fear following reinstatement. We observed that CS-US pairings can enhance fear reactions beyond the effect of contingency instructions. Moreover, for all measures of fear, instructions elicited immediate fear reactions that could not be completely overridden by subsequent situational safety information. Finally, return of fear following reinstatement for instructed CS+s was unaffected by actual experience. In sum, our results demonstrate the power of contingency instructions and reveal the additional impact of actual experience of CS-US pairings.
Mertens, G., & De Houwer, J. (2016). Potentiation of the startle reflex is in line with contingency reversal instructions rather than the conditioning history. Biological Psychology, 113, 91-99.
In the context of fear conditioning, different psychophysiological measures have been related to different learning processes. Specifically, skin conductance responses (SCRs) have been related to cognitive expectancy learning, while fear potentiated startle (FPS) has been proposed to reflect affective learning that operates according to simple associative learning principles. On the basis of this two level account of fear conditioning we predicted that FPS should be less affected by verbal instructions and more affected by direct experience than SCRs. We tested this hypothesis by informing participants that contingencies would be reversed after a differential conditioning phase. Our results indicate that contingency reversal instructions led to an immediate and complete reversal of FPS regardless of the previous conditioning history. This change was accompanied by similar changes on US expectancy ratings and SCRs. These results conform with an expectancy model of fear conditioning but argue against a two level account of fear conditioning.
Mertens, G., & De Houwer, J. (2016). The impact of a context switch and context instructions on the return of verbally conditioned fear. Journal of Behavior Therapy and Experimental Psychiatry, 51, 10-18.
Background and Objectives: Repeated exposure to a conditioned stimulus can lead to a reduction of conditioned fear responses towards this stimulus (i.e., extinction). However, this reduction is often fragile and sensitive to contextual changes. In the current study, we investigated whether extinction of fear responses established through verbal threat instructions is also sensitive to contextual changes. We additionally examined whether verbal instructions can strengthen the effects of a context change.
Methods: Fifty-two participants were informed that one colored rectangle would be predictive of an electrocutaneous stimulus, while another colored rectangle was instructed to be safe. Half of these participants were additionally informed that this contingency would only hold when the background of the computer screen had a particular color but not when it had another color. After these instructions, the participants went through an unannounced extinction phase that was followed by a context switch.
Results: Results indicate that extinguished verbally conditioned fear responses can return after a context switch, although only as indexed by self-reported expectancy ratings. This effect was stronger when participants were told that CS-US contingency would depend on the background color, in which case a return of fear was also observed on physiological measures of fear.
Limitations: Extinction was not very pronounced in this study, possibly limiting the extent to which return of fear could be observed on physiological measures.
Conclusions: Contextual cues can impact the return of fear established via verbal instructions. Verbal instructions can further strengthen the contextual control of fear.
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).
