PERSONALITY AND MODULATION OF THE STARTLE REFLEX BY EMOTIONALLY-TONEDFILMCLIPS

Several researchers have found that pleasant foreground stimuli attenu ate the eyeblink component of the startle reflex while unpleasant fore ground stimuli potentiate it. The effects of personality factors on su ch modulation of the eyeblink response, as measured by electromyograph ic (EMG) activity in reaction to loud acoustic startle probes, were ex amined in subjects viewing emotionally-toned (pleasant, unpleasant and neutral) filmclips. During the main part of the experiment, introvert s had higher baseline EMG activity and lower response probability than extraverts; no differences were observed at the beginning of the expe riment, during an acclimatization session. Reflex modulation, as measu red by response latency, was influenced by the Psychoticism (P) factor of the Eysenck Personality Questionnaire: subjects high on P showed l onger latencies to eyeblink onset when probed during Viewing of pleasa nt filmclips than subjects low on this dimension; no significant diffe rences were observed between subjects low and high on P for neutral an d unpleasant filmclips. No influence of personality factors was found on affective modulation as measured by response amplitude/magnitude. T he results are discussed in relation to Gray's and Eysenck's theories of personality. Copyright (C) 1996 Elsevier Science Ltd.