Generalization of socially transmitted and instructed avoidance

Abstract

Excessive avoidance behavior, in which an instrumental action prevents an upcoming aversive event, is a defining feature of anxiety disorders. Left unchecked, both fear and avoidance of potentially threatening stimuli may generalize to perceptually related stimuli and situations. The behavioral consequences of generalization mean that aversive learning experiences with specific threats may lead to the inference that classes of related stimuli are threatening, potentially dangerous, and need to be avoided, despite differences in physical form. Little is known however about avoidance generalization in humans and the learning pathways by which it may be transmitted. In the present study, we compared two pathways to avoidance-instructions and social observation-on subsequent generalization of avoidance behavior, fear expectancy and physiological arousal. Participants first learned that one cue was a danger cue (conditioned stimulus, CS+) and another was a safety cue (CS-). Groups were then either instructed that a simple avoidance response in the presence of the CS+ cancelled upcoming shock (instructed-learning group) or observed a short movie showing a demonstrator performing the avoidance response to prevent shock (observational-learning group). During generalization testing, danger and safety cues were presented along with generalization stimuli that parametrically varied in perceptual similarity to the CS+. Reinstatement of fear and avoidance was also tested. Findings demonstrate, for the first time, generalization of socially transmitted and instructed avoidance: both groups showed comparable generalization gradients in fear expectancy, avoidance behavior and arousal. Return of fear was evident, suggesting that generalized avoidance remains persistent following extinction testing. The utility of the present paradigm for research on avoidance generalization is discussed.

Keywords: anxiety disorders; avoidance; fear-conditioning; generalization; instructed-learning; observational-learning.

Figure 1

Conditioning and generalization stimuli. The conditioned stimuli (CS+ and CS−) were counterbalanced across participants, such that for half of the participants (group A) the CS+ was the largest of the circles and CS− was the smallest. This was reversed for the other half (group B). The generalization stimuli were circles of intermediate sizes between CS+ and CS−, gradually increasing in size for group B and gradually decreasing in size for group A. The ΔCS− was the same for all participants. The smallest circle had a diameter of 5 cm, increasing progressively in size by 15% for each stimulus, such that the second smallest circle was 15% larger than the first and 15% smaller than the next (i.e., 5 cm, 5.8 cm, 6.6 cm, 7.6 cm, 8.7 cm). The ΔCS− had a width and height of 6.6 cm, comparable to that of the GS₂, which also remained the same across groups.

Figure 2

Instructed-learning and observational-learning of avoidance. After fear conditioning, an individual was instructed how and when to perform the avoidance response (mouse click) in the presence of CS+ (A) or observed a learning model performing the avoidance response (B).

Figure 3

Fear conditioning results. Trial by trial unconditioned stimulus (US) expectancy (A) and mean skin conductance response (SCR) (μS) (square-root transformed) (B) results for CS+ and CS− presentations during fear conditioning for the instructed-learning and observational-learning groups. Error bars indicate SEM.

Figure 4

Generalization test results. Trial by trial US expectancy (A), proportion of avoidance behavior (B), and mean SCR (μS) (square-root transformed) (C) results for conditioning (CS+ and CS−) and generalization stimuli (G₁, G₂, G₃) during generalization testing for the instructed-learning and observational-learning groups (avoidable trials only). Error bars indicate SEM. Linear and/or quadratic terms are also shown.

Figure 5

Reinstatement test results. Trial by trial US expectancy (A), proportion of avoidance behavior (B), and mean SCR (μS) (square-root transformed) (C) results for conditioning (CS+ and CS−) and generalization stimuli (G₁, G₂, G₃) during reinstatement testing for the instructed-learning and observational-learning groups (avoidable trials only). Error bars indicate SEM. Linear and/or quadratic terms are also shown.