Does fear expectancy prime fear? An autonomic study in spider phobics.

This study investigated whether fear expectancy in phobic individuals induces priming of the defensive system, thus generating a "blind" phobic response even to non-phobic stimuli. We employed a paradigm in which two different visual cues signalled the upcoming picture presentation of either a spider or an innocuous animal (congruent condition). Unknown to the participants, the visual cue was incorrectly followed by a picture from the opposite category on two additional trials (incongruent condition). Cardiac and skin conductance responses were recorded from young adults with (n=15) or without (n=14) spider phobia during both the expectation and exposure of these pictures in the congruent and incongruent conditions. In the congruent condition, the autonomic responses during expectation matched the responses during exposure. In particular, non-phobic controls showed an orienting response (bradycardia and moderate skin conductance increase) to both picture categories, while spider phobics showed an orienting response to the innocuous animals and a defence response (tachycardia and marked skin conductance increase) to spiders. In the incongruent condition, the autonomic responses during exposure were driven by the affective content of the pictures, and their amplitude was greater than in the congruent condition, likely due to the signal-stimulus discrepancy. In particular, the response to the innocuous picture of phobic participants expecting a spider did not shift in the direction of the defence response. Thus, spider phobics did not show priming of the defensive system but maintained discrimination between phobic and innocuous stimuli. Finally, the greatly amplified response to the incorrectly signalled spider in phobics suggests a discrepancy-phobia interaction.