The effects of single-session exposure treatment for spider fear on emotional modulation of startle
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Although uncontrolled evidence suggests that potentiation of the startle eyeblink during phobia-relevant stimuli is sensitive to the effects of behavior therapy, no previous work has included a control group. The present study addressed this gap by investigating affective startle modulation among 48 spider fearful adults (36 women, 18 men) who were randomized to 1 hour of either in-vivo exposure therapy with a live spider or quiet reading (wait-list control). Pre- and post-treatment/control assessments included standard phobia-relevant questionnaires and psychophysiological (startle and heart rate), subjective (valence and arousal ratings), and behavioral (viewing time) measures gathered as participants watched a series of spider, negative, neutral and positive pictures. Analyses of all self-report measures demonstrated robust treatment effects. Although startle was reliably potentiated during spider compared with neutral materials overall, the effect was weak and nonsignificant during the pre-treatment assessment, making treatment effects difficult to assess. Nonetheless, spider-potentiated startle was reliably correlated with self-reported fear of spiders at pre and, among the treatment group, change in startle responding was significantly correlated with change in self-reported fear. Supplemental analysis of the more commonly used spider versus positive affective comparison yielded the expected pattern: fear-potentiated startle in both groups at pre, and in the control group but not the treatment group at post; however, the critical interaction only approached significance when the sample was restricted based on treatment response on questionnaires. These data provide modest support for the utility of the startle reflex as a psychophysiological index of treatment effects in specific phobia.