Individual differences of the startle response :implications of attention and arousal
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This study investigated the electromyogram eyeblink startle response in relationship to individual differences in dimensions of attention and arousability as assessed by the Cognitive Failures Questionnaire (Broadbent, Cooper, Fitzgerald & Parkes, 1982) and the Arousal Predisposition Scale (Coren, 1990). Individuals (n=48) fulfilling the cutoff criteria of the questionnaires compiled three groups: High Arousal/High Cognitive Failures, High Arousal/Low Cognitive Failures and Low Arousal/Low Cognitive Failures. The eyeblink startle response was examined in two conditions, one in which participants were instructed to attend to loud, startling acoustic stimuli and a second in which they were instructed to ignore the startling stimuli by mentally counting backwards by threes. It was hypothesized that groups would differ from each other in both amplitude and latency of their startle response. More specifically, if top-down controlled attentional processes mediated the startle response under such conditions, it was expected that those with less distractibility would exhibit less startle during the ignore task than those who were more distractible. If arousal level mediated the startle response, it was expected that those with high arousability would exhibit increased overall startle response. If the ignore condition was more arousing, it was expected that those with high arousability would exhibit more startle during the ignore condition than those with low arousability. It was expected that the startle response between men and women would differ significantly. Furthermore, it was hypothesized that those participants reporting high distractibility would demonstrate a larger Stroop Effect than those reporting low distractibility.
Results indicated that for mean startle response amplitude there was a significant Attention Group X Condition interaction but not an Arousal Group X Condition interaction. Post hoc tests did not reveal one condition to be greater in mean amplitude than another. When including sex as a factor, for mean onset latency there was a significant Attention X Gender interaction and a significant Arousal X Gender interaction. High arousal and high distractible men also showed significantly more significantly more startling than low distractible men and low distractible women. There were no significant differences of the Stroop Effect found between high and low distractible participants. Taken together, it appears that controlled top-down processing can influence the startle response when manipulations of the direction of attention are given. It also appears that men are more extreme in their responsivity than women. Implications for future research are discussed.
- Masters Theses