The present study compared the impact of symbolic equivalence and opposition relations on fear generalization. In a procedure using nonsense words, some stimuli became symbolically equivalent to an aversively conditioned stimulus while others were symbolically opposite.
The generalization of fear to equivalently and oppositely related stimuli was then measured using behavioural avoidance, retrospective US expectancy and stimulus valence ratings.
Equivalence relations facilitated fear generalization while opposition relations constrained generalization. The potential clinical implications of symbolic generalization discussed.