Covariation bias and electrodermal responding in spider phobics before and after behavioural treatment

Abstract

The present study investigated whether a covariation bias is present in severe spider phobics and whether such bias is modified by successful treatment. In addition, this study sought to examine whether a covariation bias is linked to differential autonomic responding. Subjects were 20 untreated phobics, 19 treated phobics, and 18 no-fear controls. Subjects were exposed to a series of 72 slides comprising three categories: spiders (fear-relevant), mushrooms, and flowers. At slide offset one of three possible outcomes occurred: a shock, a tone, or nothing at all. All slide-outcome combinations occurred equally frequent. The results show that an equally strong covariation bias is present in severe spider phobics, in successfully treated phobics, and in no-fear controls. Thus, the present data only partially sustain earlier findings of Tomarken A.J., Mineka S. & Cook M. (1989) (Journal of Abnormal Psychology, 98, 381–394). The covariation bias appeared to be mimicked by differentially heightened autonomic responding. The current data suggest that both the covariation bias and the heightened physiological responding reflect a “beloningness” between spider slides and aversive outcome.