More engagement in inefficient avoidance through partial reinforcement

Working hard to avoid: Fixed-ratio response effort and maladaptive avoidance in humans

Maladaptive avoidance of safe stimuli is a defining feature of anxiety and related disorders. Avoidance may involve physical effort or the completion of a fixed series of responses to prevent occurrence of, or cues associated with, the aversive event. Understanding the role of response effort in the acquisition and extinction of avoidance may facilitate the development of new clinical treatments for maladaptive avoidance. Despite this, little is known about the impact of response effort on extinction-resistant avoidance in humans. Here, we describe findings from two laboratory-based treatment studies designed to investigate the impact of high and low response effort on the extinction (Experiment 1) and return (Experiment 2) of avoidance. Response effort was operationalised as completion of fixed-ratio (FR) reinforcement schedules for both danger and safety cues in a multi-cue avoidance paradigm with behavioural, self-report, and physiology measures. Completion of the FR response requirements cancelled upcoming shock presentations following danger cues and had no impact on the consequences that followed safety cues. Both experiments found persistence of high response-effort avoidance across danger and safety cues and sustained (Experiment 1) and reinstated (Experiment 2) levels of fear and threat expectancy. Skin conductance responses evoked by all cues were similar across experiments. The present findings and paradigm have implications for translational research on maladaptive anxious coping and treatment development.

The role of relief, perceived control, and prospective intolerance of uncertainty in excessive avoidance in uncertain-threat environments

Excessive avoidance is a key feature of pathological anxiety. However, the precise mechanisms underlying the development of excessive avoidance are still unknown. In the present study, we tested the hypothesis that excessive avoidance, especially in individuals with high Intolerance of Uncertainty (IU) is aimed at distress reduction via the enhancement of subjective perceived control in uncertain-threat environments. In our experiment, participants learned to avoid an uncertain aversive sound through a discriminated free operant procedure. In a later test phase in extinction, we manipulated the amount of avoidance responses available per trial by creating a limited and an unrestricted response condition. Nonetheless, the aversive sound could be effectively avoided in both conditions. We measured response frequency, avoidance confidence ratings and anxiety-predisposing traits such as intolerance of uncertainty, trait anxiety and distress tolerance. The degree of distress suffered during trials was inferred from post-trial relief ratings that were requested after trials in which the aversive sound had been omitted. In the avoidance acquisition phase, we found a positive association between prospective intolerance of uncertainty (P-IU) and the decline rate of distress. This relationship was not significant, however, when inhibitory intolerance of uncertainty (I-IU) was controlled for. At test, we found that the increase in avoidance responses led to distress reduction through the enhancement of avoidance confidence. Finally, we found a significant modulating role of P-IU in the effect of response limit on distress reduction that lends further support to our hypothesis. Specifically, P-IU was positively associated with the effect of response limit on distress. However, such modulating role was not significant when controlling for trait anxiety or I-IU.