A neural correlate of the visual temporal-dilation aftereffect
26.306, Saturday, May 11, 2:45 - 6:45 pm, Royal Ballroom 6-8
Jose Emmanuel Guzman-Martinez1, Laura Ortega1, Marcia Grabowecky1,2, Satoru Suzuki1,2; 1Department of Psychology, Northwestern University, Evanston, IL, USA, 2Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA
We previously showed that several seconds of adaptation to a flickered stimulus makes a subsequently presented brief static stimulus appear longer in duration (Ortega et al., 2012). We investigated a neural correlate of this temporal-dilation aftereffect by recording event-related potentials (ERPs). Research in visual time perception has shown that stimulus duration is positively correlated with the peak latency of a negative ERP deflection, known as the contingent negative variation (CNV). If the visual temporal-dilation aftereffect alters duration representation in temporal mechanisms reflected in the CNV then the delay in the latency of the CNV peak should be positively correlated with the magnitude of the temporal-dilation aftereffect. We measured the magnitude of temporal-dilation aftereffects using a temporal-bisection task in which participants classified test stimuli (ranging from 200-800 ms) as closer to a short or to a long reference duration. In this paradigm, a shorter (left-shifted) point of subjective equality (PSE) indicates a longer perceived duration. Each test stimulus was randomly preceded by a flickered or static (control) adaptor, and the difference in the PSE between these adaptors indicated the magnitude of the temporal-dilation aftereffect. When the aftereffect generated a longer duration representation, the difference in the CNV peak latency (from the test stimulus onset) between the flickered and static adaptation conditions should be positively correlated with the corresponding PSE difference across participants. Indeed, we found a robust positive correlation between the CNV latency difference and the PSE difference (r=0.758, t= 3.85, p<0.01). Thus, the CNV peak latency provides a neural correlate of temporal dilation from flicker adaptation.