Biological vs experiential factors in phobic conditioning

The present study was performed as a test of phobic conditioning being a case of prepared learning (Seligman, 1971). Skin conductance responses were conditioned in three groups of subjects to either slides of snakes and spiders; electric outlets; or geometric shapes, as conditioned stimuli (CSs) with shock to the forearm as the unconditioned stimulus (UCS). The purpose of the experiment was to compare electrodermal conditioning to potentially phobic CSs, i.e. snakes and spiders, with conditioning to fear-relevant, but non-phobic, CSs, i.e. electric outlets.Each subject saw two pictures, either a snake or a spider; or two different slides of electric outlets; or two different geometric shapes. Only one of the two cues (the CS + ) was immediately followed by the shock-UCS during the acquisition phase. Thus, a differential paradigm was used. There were 4 habituation, 12 acquisition, and 16 extinction trials. The duration of the pictures was 8 sec with an intertrial interval of between 35–45 sec.The results showed reliable effects of conditioning in all three groups during the acquisition phase. Furthermore, a significant interaction during extinction is reported, indicating responses to potentially phobic CSs to be more resistant to extinction than responses to the other two classes of stimuli. It is concluded that the present results favor an interpretation of phobic conditioning in terms of biologically prepared learning.