Abstract
PURPOSE. We have examined the rate of acquisition of information from briefly presented pictures rated to be of different emotional valences to establish the dynamics of perception and short term memory accumulation of emotional content in real-life scenes.
METHODS. Stimuli were color photographs with emotional valence ranging from extremely negative to extremely positive, drawn from the International Affective Picture System set. We used the RSVP procedure to present 8 pictures (different valences interspersed and counterbalanced across subjects) with durations per picture ranging from 13msec to 4sec. Following each 8-picture stream, subjects were shown 16 pictures singly (8 seen and 8 new), and asked to judge whether the given picture was present in the stream they just saw. 96 naïve subjects were tested, and their accuracy data were fitted with Weibull functions to compare the time to criterion performance and the rate of information acquisition for different valence categories.
RESULTS. Asymptotic performance in this task (∼ 96% correct) is reached by 2sec of presentation per scene. Performance on both positive and negative stimuli reaches criterion significantly faster than performance on neutral stimuli, as expected given their higher arousal value. The rate of memory acquisition, however, is significantly different for negative and positive scenes. This is seen clearly by examining the derived hazard functions, which show a constant instantaneous rate of memory accumulation for positive and neutral scenes, but an accelerating function for negative scenes.
CONCLUSION. These results demonstrate that negatively tagged information is initially suppressed, but later processed more quickly than information with positive valence. We raise the possibility that human visual short-term memory is affected by a brief “freezing response,” followed by a preferential accelerated encoding of negatively tagged information.