THE STARTLE PROBE RESPONSE AS AN INSTRUMENT FOR EVALUATING EXPOSURE EFFECTS IN SPIDER PHOBIA

Before treatment, immediately after treatment and at one week follow u p, acoustic probes eliciting eyeblink startles were presented to 37 fe male spider phobics during a behavioral approach test (BAT). To obtain control startles, the subjects also carried out a BAT with a block of wood (neutral foreground) and a BAT with tasty food items (positive f oreground). During the pretreatment assessment eyeblink startle magnit udes did not significantly differ among the three BAT conditions. For all conditions, startle responses were larger during the pre- than dur ing the post-treatment and follow-up assessments. This possibly reflec ts a general fear-induced startle potentiation during the pretreatment session, due to subjects' anticipating exposure to spiders. At one we ek follow up, the expected linear trend between affective valence (BAT conditions) and startle magnitude emerged, despite the fact that at t his time spider startles were significantly smaller than those before treatment. The self-reported startles closely mimicked the pattern of eyeblink startle responses. The present study indicates that the start le response might be a fruitful outcome variable, indexing aspects of phobia not covered by the more commonly used outcome measures. Yet, it s prognostic properties remain to be established.