The visual system is exquisitely adapted to the task of extracting conceptual information from visual input with every new eye fixation, three or four times a second. Here we assess the minimum viewing time needed for visual comprehension, using rapid serial visual presentation (RSVP) of a series of six or 12 pictures presented at between 13 and 80 ms per picture, with no interstimulus interval. Participants were to detect a picture specified by a name (e.g., smiling couple) that was given just before or immediately after the sequence. Detection improved with increasing duration and was better when the name was presented before the sequence, but performance was significantly above chance at all durations, whether the target was named before or only after the sequence. The results are consistent with feedforward models, in which an initial wave of neural activity through the ventral stream is sufficient to allow identification of a complex visual stimulus in a single forward pass. Although we discuss other explanations, the results suggest that neither reentrant processing from higher to lower levels nor advance information about the stimulus is necessary for the conscious detection of rapidly presented, complex visual information.

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The detection of change over time is critical to the serial integration of reality. Three pigeons, in a same/different go/no-go discrimination, were rewarded for pecking at changing stimuli that oscillated back and forth in brightness over a specific range and not at constant, unchanging stimuli randomly selected from the same range. Experiment 1 tested their capacity to detect increasingly slower rates of change against a constant control. The results indicated that pigeons retrospectively integrate past experience over approximately 20-30 s. Experiment 2 tested combinations of brightness ranges and rates to examine the possible roles of perception and memory in this discrimination. Overall, the results indicate that pigeons can detect continuous changes in brightness over different temporal durations, and several lines of evidence suggest that a combination of perception and memory mechanisms are involved. Implications for the pigeons'experience of the recent past are considered.

Enhanced perception may allow for visual search superiority by individuals with Autism Spectrum Disorder (ASD), but does it occur over time? We tested high-functioning children with ASD, typically developing (TD) children, and TD adults in two tasks at three presentation rates (50, 83.3, & 116.7 ms/item) using rapid serial visual presentation (RSVP). In the Color task, participants detected a purple target letter amongst black letter distractors. In the Category task, participants detected a letter amongst number distractors. Slower rates resulted in higher accuracy. Children with ASD were more accurate than TD children and similar to adults at the fastest rate when detecting color-marked targets, indicating atypical neurodevelopment in ASD may cause generalized perceptual enhancement relative to typically developing peers.