Duration adaptation modulates EEG correlates of subsequent temporal encoding

Repetitive exposure to relatively long or short sensory events has been shown to shorten or lengthen the perceived duration of a subsequent event. However, the neural basis of this phenomenon, called duration adaptation, remains unclear. In this study, we used electroencephalography (EEG) to investigate whether duration adaptation could modulate the subsequent temporal encoding represented by the contingent negative variation (CNV). Participants were asked to reproduce the duration of a test stimulus after adapting duration (Experiment 1) or after anchor duration (Experiment 2). We found that both adapting duration and anchor duration affected the reproduction duration of a subsequently presented test stimulus. The simultaneously recorded event-related potentials (ERPs) revealed that test stimuli evoked clearly identifiable Ni, P2 and CNV components in the fronto-central scalp. Further analyses showed that the CNV amplitude was modulated by duration adaptation: adaptation to shorter duration (200 ms) increased whereas adaptation to longer duration (800 ms) decreased the CNV amplitude. These findings suggest that the neural correlates of temporal encoding represented by the CNV amplitude reflect the duration aftereffect. Additionally, the duration adaptation effect observed on the P2 component also suggests an early expectancy effect on subsequent encoding processes. Finally, no effect of anchor duration was observed on the CNV amplitude, which implies that different mechanisms underlie the duration aftereffect and the anchor effect.