Abstract
The visual system can efficiently summarize visual scenes by grouping similar features together (e.g., average orientation of lines), providing an efficient way for the visual system to overcome the limitations of visual consciousness. Although individual and ensemble information is hierarchical, what happens to the ensemble representation as individual item information becomes less available? In this study, we explored how varying interstimulus interval (ISI) affected orientation representation at both the individual and ensemble levels. In the first experiment, observers viewed sets of four oriented gabors for 1 second, followed by a 250 ms cue to one of the four items. Observers reported the orientation of the cued item using continuous report. ISI varied from among 250 ms, 2s, and 4 s. We analyzed the precision of individual item representation as a function of time, but also examined the precision of the ensemble representation over time, which observers were not explicitly asked about. Although we expected ensemble precision to improve and individual item precision to decline as ISI increased (reflecting a greater reliance on the ensemble as memory for the individual item deteriorated), we found no change in performance over time for either the individual or the ensemble. In the second experiment, the design was similar except that observers were explicitly cued to report the orientation of a single individual or the average orientation of the whole set. Replicating the results of the first experiment, there was no change in performance as a function of ISI for either condition, although ensemble performance was slightly but consistently worse than individual item performance. Overall, these findings suggest that both ensemble and individual information is immediately and continuously accessible; the visual system seemingly has both representations simultaneously active for a surprisingly long time.