Psychophysical investigation of visual time perception. (360G-Wellcome-090369_Z_09_Z)

Traditionally time perception has been considered the product of a central, supramodal, content-independent cognitive mechanism (Creelman, 1962; Treisman, 1963): a pacemaker generates impulses at a set rate and the duration of an interval is determined by gating the impulses to an accumulator. This model attributes duration distortions to changes in state variables such as arousal. However, recent research (Johnston et al., 2006; Burr et al., 2007; Johnston et al., 2008) has shown that the appar ent duration of a visual stimulus can be compressed at a unique spatial location by a magno-specific visual adaptation (high temporal frequency, low spatial frequency flicker or drifting motion). These observations motivate a new modality-specific approach to the study of time perception. We aim to investigate how the estimated duration of a visual interval can be influenced by its content and by the adaptive state of the visual system. We will study (a) how changes in the temporal tuning charac teristics of the early visual pathway are related to adaptation-induced time distortions; (b) whether time distortions occur in a retinocentric or headcentric frame of reference; (c) what role attention plays in these effects.