Effects of varied-stimulus exposure training on fear reduction and return of fear.

The current investigation assessed the relative treatment benefits of persistence with one specific stimulus vs exposure to multiple versions of a stimulus. The study was a 2 (type of stimulus) x 3 (assessment occasion) design, in which two spider-fearful groups (N = 28) were compared across three different occasions: pre-treatment, post-treatment, and follow-up. Exposure trials were conducted with the same tarantula for participants in the control group, whereas experimental participants were exposed to four novel tarantulas. As predicted, the control group demonstrated significantly more habituation than the experimental group across exposure trials, yet showed a clear return of fear in response to a control spider at a 3-week follow-up assessment whereas the experimental group showed no increase in fear. These findings offer support for the beneficial effects of varying the stimulus during exposure, and challenge the reliance on indices of fear activation and habituation as accurate signals of the permanence of fear reduction.