The relative importance of perceptual and memory sampling processes in determining the time course of absolute identification

In absolute identification, the extended generalized context model (EGCM; Kent & Lamberts, 2005, 2016) proposes that perceptual processing determines systematic response time (RT) variability; all other models of RT emphasize response selection processes. In the EGCM-RT the bow effect in RTs (longer responses for stimuli in the middle of the range) occurs because these middle stimuli are less isolated, and as perceptual information is accumulated, the evidence supporting a correct response grows more slowly than for stimuli at the ends of the range. More perceptual information is therefore accumulated in order to increase certainty in response for middle stimuli, lengthening RT. According to the model reducing perceptual sampling time should reduce the size of the bow effect in RT. We tested this hypothesis in 2 pitch identification experiments. Experiment 1 found no effect of stimulus duration on the size of the RT bow. Experiment 2 used multiple short stimulus durations as well as manipulating set size and stimulus spacing. Contrary to EGCM-RT predictions, the bow effect on RTs was large for even very short durations. A new version of the EGCM-RT could only capture this, alongside the effect of stimulus duration on accuracy, by including both a perceptual and a memory sampling process. A modified version of the selective attention, mapping, and ballistic accumulator model (Brown, Marley, Donkin, & Heathcote, 2008) could also capture the data, by assuming psychophysical noise diminishes with increased exposure duration. This modeling suggests systematic variability in RT in absolute identification is largely determined by memory sampling and response selection processes.