Affective reactions to briefly presented pictures

Affective reactions to briefly presented pictures were investigated to dete rmine whether fleeting stimuli engage the motivational systems mediating em otional responses. Emotional and neutral pictures were presented for 500 ms : heart rate, skin conductance. corrugator EMG. and the evoked startle refl ex were measured. The time course of reflex modulation was similar to that obtained with longer (6 s) presentations, suggesting that picture processin g continues in the absence of a sensory stimulus. Affective reactions found with more sustained presentation were also obtained, with more corrugator EMG activity for unpleasant pictures, and greater skin conductance reactivi ty for emotional pictures. Heart rate modulation, however. appears to rely on the presence of a sensory stimulus. The data also suggest that brief pre sentations of unpleasant pictures may result in less defensive activation t han sustained presentation.