Personality Correlates of Startle Habituation: An Examination in Three Separate Samples

Personality traits have been shown to longitudinally predict the onset of anxiety disorders (Clark, Watson, & Mineka, 1994; Hayward, Killen, Kraemer, & Taylor, 2000). One process that may be at the core of the personality-anxiety relation is a deficit in habituation, or the decrease in response to repeated aversive stimuli over time (Harris, 1943). Past research suggests that individuals with anxiety disorders show reduced physiological habituation to aversive stimuli, including galvanic skin response (Lader & Wing, 1964; Rothbaum, Kozak, Foa, & Whitaker, 2001) and acoustic startle response (Ludewig et al., 2005). Less is known about the relationship between personality and habituation. However, if individuals with anxiety disorders show patterns of disrupted physiological habituation, and certain personality traits (i.e. AS and/or N) are known to correlate highly with (and often predict) anxiety disorders, it is possible that personality would predict differences in habituation. The present study examined whether AS and/or N was associated with habituation during a 9-blink, 2.5 minute baseline startle period in three separate samples of undergraduates (total N=284). Additionally, because of the widely varying methodological definitions of physiological habituation used in past studies (LaRowe, Patrick, Curtin, & Kline, 2006; Rothbaum et al., 2001), three definitions of startle habituation were examined in hopes of eliciting the most appropriate measure of the construct. Results indicated that higher levels of AS but not N evidenced reduced startle habituation, but the strength of this relationship was dependent on the definition of habituation used. The most robust definition of habituation involved an examination of the individual slopes across each of the nine blinks, which revealed significant linear and quadratic effects. Clinical implications are discussed relating the present findings to an understanding of the pathogenesis of anxiety disorders in high-risk populations.