Fragile memories for fleeting percepts

Abstract

Our perceptual systems are exceptionally good at searching our sensory environments for salient stimuli. A key question is the extent to which this search is performed subliminally. Consistent with our tokenized-percept theory, we hypothesis that it is. We explore this using Rapid Serial Visual Presentation (RSVP), by comparing detection performance with the memory left for distractors, the stimuli that have to be rejected as non-targets in the process of searching for targets. In agreement with our hypothesis, our findings are that “immediate” free recall of arbitrary distractors at RSVP rates is very poor, with a severe recency effect. Recognition performance was higher and less subject to recency, but still substantially lower than detection performance. These findings suggest that the brain does indeed subliminally search for salient stimuli, providing evidence for the tokenized-percept hypothesis, which links conscious perception to the process of episodically marking experiences.