Failure to detect meaning in RSVP at 27 ms per picture.

The human visual system has the remarkable ability to rapidly detect meaning from visual stimuli. Potter, Wyble, Hagmann, and McCourt (Attention, Perception, & Psychophysics, 76, 270-279, 2014) tested the minimum viewing time required to obtain meaning from a stream of pictures shown in a rapid serial visual presentation (RSVP) sequence containing either six or 12 pictures. They reported that observers could detect the presence of a target picture specified by name (e.g., smiling couple) even when the pictures in the sequence were presented for just 13 ms each. Potter et al. claimed that this was insufficient time for feedback processing to occur, so feedforward processing alone must be able to generate conscious awareness of the target pictures. A potential confound in their study is that the pictures in the RSVP sequence sometime contained areas with no high-contrast edges, and so may not have adequately masked each other. Consequently, iconic memories of portions of the target pictures may have persisted in the visual system, thereby increasing the effective presentation time. Our study addressed this issue by redoing the Potter et al. study, but using four different types of masks. We found that when adequate masking was used, no evidence emerged that observers could detect the presence of a specific target picture, even when each picture in the RSVP sequence was presented for 27 ms. On the basis of these findings, we cannot rule out the possibility that feedback processing is necessary for individual pictures to be recognized.