Abstract
The preparedness theory of phobias holds that responses conditioned to fear-relevant stimuli are insensitive to cognitive-instructional variables. This hypothesis was tested in an electrodermal conditioning experiment in which 16 college students were presented with two fear-relevant stimuli, a picture of a snake and a picture of a spider. One stimulus was reinforced with shock while the other was not. After discrimination training, the subjects were informed that the CS-US contingencies were reversed. They were told that shock would no longer follow the previously reinforced stimulus but might follow the previously nonreinforced stimulus. Actually, no further shocks were delivered. The instructional manipulation produced an immediate reversal of the conditioned electrodermal response curves. The results are inconsistent with the hypothesis that responses conditioned to fear-relevant stimuli are insensitive to cognitive-instrumental variables.