Does Presentation Duration Modulate the Effect of Task on Perceptual Organization?

Visual symmetry activates the extrastriate cortex. This symmetry activation generates an Event Related Potential (ERP) named the Sustained Posterior Negativity (SPN). The SPN is larger when participants engage in regularity discrimination tasks than luminance discrimination tasks. Two recent studies suggest that the type of task matters more when the stimulus is presented briefly. We tested this claim with a new sample of 52 participants in a within-subjects design. As predicted, the SPNs were larger in Regularity tasks than Luminance tasks. However, contrary to predictions, the effect of the task was very similar in long and short presentation duration blocks. It remains unclear what factors modulate the task effect. However, presentation duration is not as important as previous results suggest.