EMOTIONAL MODULATION OF THE STARTLE REFLEX IN TWINS - PRELIMINARY FINDINGS

This study investigated twin similarity in general startle reflex reac tivity and emotional modulation. Seventeen monozygotic (MZ) and 12 diz ygotic (DZ) male twin pairs received startling acoustic stimuli while viewing emotionally positive, negative and neutral slides. Electromyog raphic (EMG) responses were recorded from the orbicularis oculi. Membe rs of MZ twin pairs had similar response amplitudes under all three va lence conditions. In addition, modulation scores for the positive and negative conditions, representing the percent change in response ampli tude between the affective and the neutral conditions, also showed sig nificant similarity within MZ twin pairs. Overall, members of DZ twin pairs were not found to be significantly similar on any of the measure s. These preliminary findings suggest that emotional modulation of the startle reflex shows familial resemblance within MZ pairs. Given the lack of resemblance between DZ twins, it is tentatively suggested that affective modulation may be under partial genetic control. (C) 1997 E lsevier Science B.V.