Variable processing shifts during perceptual acceleration: Evidence from temporal integration

The perception of a stimulus can be accelerated by another that precedes it. Perceptual acceleration has been observed in a range of tasks, at varying timescales, and arises by virtue of providing advance spatial and/or temporal information about upcoming stimuli. Here we examined perceptual acceleration during visual temporal integration. Temporal integration occurs when successive stimuli appear that fit together in time as well as space. As such, stimuli arriving first during temporal integration partially predict those that follow. Although temporal integration is a rapid process, we reasoned that this information may cause perceptual acceleration during temporal integration. We used multivariate pattern analysis of EEG data from a missing element task, designed to measure the visual temporal integration of two successive stimulus displays, so that we were able to precisely track the representation associated with the integrated percept in time. We manipulated the delay between our displays, and observed commensurate acceleration of the resultant integrated representation. The degree of acceleration first increased from early (100 ms after stimulus onset) to intermediate (200 ms) processing stages, before decreasing again at a later stage (400 ms). The results thus suggest that perceptual acceleration occurs during temporal integration, but is nonlinear, such that some time that is gained at one moment in the process can be lost again at another.