MANIPULATING AFFECTIVE STATE USING EXTENDED PICTURE PRESENTATIONS

Separate, extended series of positive, negative, and neutral pictures were presented to 24 (12 men, 12 women) undergraduates. Each series wa s presented on a different day, with full counterbalancing of presenta tion orders. Affective state was measured using (a) orbicularis oculi activity in response to acoustic startle probes during picture present ation, (b) corrugator supercilii activity between and during picture p resentation, and (c) changes in self-reports of positive and negative affect. Participants exhibited larger eyeblink reflex magnitudes when viewing negative than when viewing positive pictures. Corrugator activ ity was also greater during the negative than during the positive pict ure set, during both picture presentation and the period between pictu res. Self-reports of negative affect increased in response to the nega tive picture set, and self-reports of positive affect were greatest fo llowing the positive picture set. These findings suggest that extended picture presentation is an effective method of manipulating affective state and further highlight the utility of startle probe and facial e lectromyographic measures in providing on-line readouts of affective s tate.