Electrodermal and subjective reactions to fear-relevant stimuli under threat of shock

Abstract

Three experiments investigated normal subjects' reactions to pictures of fear‐relevant stimuli (snakes, spiders, guns) and control stimuli (e.g., flowers, rabbits) under threat of electric shock. First‐interval electrodermal responses (FTRs) and shock expectancy ratings were recorded. Experiment 1 demonstrated larger FTRs and expectancy ratings to fear‐relevant stimuli, with and without threat of electric shock. In Experiment 2, trait anxious subjects showed elevated expectancy ratings that were additive with the bias associated with fear‐relevant stimuli. Experiment 3 demonstrated that reactions to fear‐relevant stimuli were not an artefact of the expectancy rating task. There were no substantial differences between biological and technological fear‐relevant stimuli. Overall, the experiments confirm that fear‐relevant stimuli elicit larger reactions in the absence of any specific manipulation, such as conditioning. The results are most consistent with cognitive models that emphasise learning rather than genetic factors, and that attribute electrodermal reactions to elevated expectancy of aversive events.