Maes, E., De Filippo, G., Inkster, A., Lea, S.E.G., De Houwer, J., D'Hooge, R., Beckers, T., Wills, A.J. (2015). Animal Cognition
Humans can spontaneously create rules that allow them to efficiently generalize what they have learned to novel situations. An enduring question is whether rule-based generalization is uniquely human or whether other animals can also abstract rules and apply them to novel situations. In recent years, there have been a number of high-profile claims that animals such as rats can learn rules. Most of those claims are quite weak because it is possible to demonstrate that simple associative systems (which do not learn rules) can account for the behavior in those tasks. Using a procedure that allows us to clearly distinguish feature-based from rule-based generalization (the Shanks-Darby procedure), we demonstrate that adult humans show rule-based generalization in this task, while generalization in rats and pigeons was based on featural overlap between stimuli. In brief, when learning that a stimulus made of two components (“AB”) predicts a different outcome than its elements (“A” and “B”), people spontaneously abstract an opposites rule and apply it to new stimuli (e.g. knowing that “C” and “D” predict one outcome, they will predict that “CD” predicts the opposite outcome). Rats and pigeons show the reverse behavior – they generalize what they have learned, but on the basis of similarity (e.g. “CD” is similar to “C” and “D”, so the same outcome is predicted for the compound stimulus as for the components). Genuinely rule-based behavior is observed in humans, but not in rats and pigeons, in the current procedure.
Van Dessel, P., De Houwer, J., Gast, A., Smith, C. T., & De Schryver, M. (2016). Instructing implicit processes: When instructions to approach or avoid influence implicit but not explicit evaluation. Journal of Experimental Social Psychology, 63, 1-9.
Previous research has shown that linking approach or avoidance actions to novel stimuli through
mere instructions causes changes in the implicit evaluation of these stimuli even when the actions
are never performed. In two high-powered experiments (total N = 1147), we examined whether
effects of approach-avoidance instructions on implicit evaluations are mediated by changes in
explicit evaluations. Participants first received information about the evaluative properties of two
fictitious social groups (e.g., Niffites are good; Luupites are bad) and then received instructions to
approach one group and avoid the other group. We observed an effect of approach-avoidance
instructions on implicit but not explicit evaluations of the groups, even when these instructions
were incompatible with the previously obtained evaluative information. These results indicate
that approach-avoidance instructions allow for unintentional changes in implicit evaluations. We
discuss implications for current theories of implicit evaluation.
Schmidt, J. R., & De Houwer, J. (in press). Contingency learning tracks with stimulus-response proportion: No evidence of misprediction costs. Experimental Psychology.
We investigate the processes involved in human contingency learning using the colour-word contingency learning paradigm. In this task, participants respond to the print colour of neutral words. Each word is most often presented in one colour. Results show that participants respond faster and more accurately to words presented in their expected colour. In Experiment 1, we observed better performance for high relative to medium frequency word-colour pairs, and for medium relative to low frequency pairs. Within the medium frequency condition, it did not matter whether the word was predictive of a currently-unpresented colour, or the colour of a currently-unpresented word. We conclude that a given word facilitates each potential response proportional to how often they co-occurred. In contrast, there was no evidence for costs associated with violations of high-frequency expectancies. Experiment 2 further introduced a novel word baseline condition but also did not provide evidence for competition between retrieved responses.
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).
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., & 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.
Boddez Y., De Houwer J., Beckers T. (2017). The inferential reasoning theory of causal learning: Towards a multi-process propositional account. In: Waldmann M. (Eds.), The Oxford Handbook of Causal Reasoning, Chapt. 4, (pp. 1-22). Oxford: Oxford University Press.
Bennett M., Vervoort E., Boddez Y., Hermans D., Baeyens F. (2015). Perceptual and conceptual similarities facilitate the generalisation of instructed fear. Journal of Behavior Therapy and Experimental Psychiatry, 48, 149-155.
Vanbrabant K., Boddez Y., Verduyn P., Mestdagh M., Hermans D., Raes F. (2015). A new approach for modeling generalization gradients: A case for hierarchical models. Frontiers in Psychology, 6, art.nr. 652, 1-10.