Els Joos

Worry as a Predictor of Fear Acquisition in a Nonclinical Sample.

People seem to differ in their conditionability, that is, the ease by which fear associations (neutral stimulus–unconditioned stimulus [CS-US] contingencies) are learned. Recently, the level of trait worry has been proposed as a predictor of heightened conditionability. The current research aimed to (a) further investigate this influence of individual differences in trait worry on the strength of fear acquisition, (b) explore whether this association could be explained by trait anxiety, and (c) assess possible underlying mechanisms of this relationship. In a nonclinical sample, the amount of trait worry predicted heightened conditionability in a differential fear conditioning paradigm, both in fear ratings and in performance on a secondary probe reaction time task. A significant correlation was observed for general conditioning to the CS+ and also for differential conditioning (taking into account excitatory and inhibitory responding) in Experiment 1. These associations could not be fully explained by trait anxiety. US inflation and strengthening of the CS-US contingency through rehearsal are discussed as possible underlying mechanisms.

Generalization of conditioned responding: Effects of autobiographical memory specificity

Generalization of acquired responses appears to be a crucial, yet under investigated process in emotional disorders. Generalization occurs when a conditioned response is elicited by a stimulus different from the original conditioned stimulus. The expansion of complaints, often seen in emotional disorders, is at least in part due to processes of generalization. In the present study, generalization is approached from a memory perspective. It is hypothesized that generalization of conditioned responding is associated with autobiographical memory specificity. Higher levels of generalization are predicted for people who are characterized by limited memory specificity. In a human contingency-learning procedure, participants learned the association between two pictures of female faces and a schematic drawing of a lightning bolt. Subsequently, six morphed pictures functioning as generalization stimuli (GSs) were introduced and conditioned responses to these GSs were measured. The results showed that memory specificity was significantly associated with the extent of generalization. Participants low in autobiographical memory specificity exhibited significantly stronger conditioned responses to GSs as compared to participants high in autobiographical memory specificity.

Post-acquisition repetitive thought in fear conditioning: an experimental investigation of the effect of CS-US-rehearsal.

BACKGROUND AND OBJECTIVES Although repetitive thought (e.g., worry) is generally assumed to be a risk factor for psychopathological disorders such as anxiety disorders, the repetitive thought processes occurring after a conditioning event have not yet received much theoretical attention. However, as repetitive thought can be mimicked by (mental) rehearsal, which is well-known to enhance memory performance, it seems worthwhile to explore the role of rehearsal in conditioning. Therefore, the current study investigates the impact of rehearsing an acquired CS-US-contingency on subsequent conditioned fear responding. METHODS After acquiring two CS-US-contingencies with either a human scream or a white noise as US, participants were instructed to rehearse one of these CS-US-pairings during an experimental session as well as during the following week. RESULTS Fear responding to the CS which was previously paired with the scream persisted in the participants who rehearsed the CS-US(scream)-contingency, but decreased in those participants who rehearsed the CS-US(noise)-contingency. The same pattern emerged in the US-expectancy ratings, but the effect failed to reach significance. For the CS which was paired with the noise-US, no rehearsal effect emerged. LIMITATIONS As acquisition to the noise-US was less pronounced and less robust as compared to the scream-US, claims regarding the rehearsal effect might be hampered for the CS-US(noise)-contingency. CONCLUSIONS Repetitive post-acquisition activation of a CS-US-contingency impacts CR retention. As the USs were not rated as more intense, aversive or startling after rehearsal compared to post-acquisition, US-inflation is discarded as a possible explanation of this effect.

Repeated activation of a CS-US-contingency memory results in sustained conditioned responding

Individuals seem to differ in conditionability, i.e., the ease by which the contingent presentation of two stimuli will lead to a conditioned response. In contemporary learning theory, individual differences in the etiology and maintenance of anxiety disorders are, among others, explained by individual differences in temperamental variables (Mineka and Zinbarg, 2006). One such individual difference variable is how people process a learning experience when the conditioning stimuli are no longer present. Repeatedly thinking about the conditioning experience, as in worry or rumination, might prolong the initial (fear) reactions and as such, might leave certain individuals more vulnerable to developing an anxiety disorder. However, in human conditioning research, relatively little attention has been devoted to the processing of a memory trace after its initial acquisition, despite its potential influences on subsequent performance. Post-acquisition processing can be induced by mental reiteration of a conditioned stimulus-unconditioned stimulus (CS-US)-contingency. Using a human conditioned suppression paradigm, we investigated the effect of repeated activations of a CS-US-contingency memory on the level of conditioned responding at a later test. Results of three experiments showed more sustained responding to a “rehearsed” CS+ as compared to a “non-rehearsed” CS+. Moreover, the second experiment showed no effect of rehearsal when only the CS was rehearsed instead of the CS-US-contingency. The third experiment demonstrated that mental CS-US-rehearsal has the same effect regardless of whether it was cued by the CS and a verbal reference to the US or by a neutral signal, making the rehearsal “purely mental.” In sum, it was demonstrated that post-acquisition activation of a CS-US-contingency memory can impact conditioned responding, underlining the importance of post-acquisition processes in conditioning. This might indicate that individuals who are more prone to mentally rehearse information condition more easily.

Repetitive Thought about an Aversive Learning Experience Maintains Conditioned Responding

Clinical anxiety is often believed to be based on fear conditioning, a procedure of pairing an originally neutral stimulus (conditioned stimulus, CS) with an aversive unconditioned stimulus (US), which results in the CS eliciting a conditioned fear response in the absence of the US. Recently, it was shown that repeatedly thinking about an aversive conditioning event maintains subsequent fear responding. A crucial question is how such effects should be interpreted. Does rehearsal of a CS-US-contingency result in a strengthened memory trace of the conditioning experience or in changes in the US-representation (e.g., US-inflation or increased US-coherence)? The current study was set up to investigate the underlying mechanism of this rehearsal effect. After acquisition training with two CS+s paired with the same US, participants rehearsed one of both CS-US-contingencies. The CS+ that was part of the rehearsed contingency elicited more US-expectancy than the CS+ that was not rehearsed. As changes in the US-representation could not explain our data, we suggest that a strengthening of the memory trace of the CS-US-association underlies this effect. Repetitive thought about a conditioning experience seems to result in sustained conditioned responding due to a strengthened CS-US-association. We propose that the repetitive nature of thought processes such as worry might partly explain its unconstructive role in anxiety.