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Title: Vision-based mechanisms of time perception
Author: Ayhan, I.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2010
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Perceived duration of brief intervals can be altered in a specific spatial location in the visual field by adaptation to oscillatory motion or flicker (Johnston et al, 2006, 2008). In the first experiment here, the spatial tuning of adaptation-based temporal distortions was investigated by varying the spatial separation of adaptor and test. It was found that adaptation-based apparent duration compression is tightly tuned to the location of the adaptor and that the effects of adaptation on perceived duration are dissociable from those on temporal frequency although the spatial tuning of these effects was similar. In a second experiment, the frame of reference (retinotopic versus spatiotopic) of adaptation effects was investigated using pursuit and saccadic paradigms. It was observed a robust time compression following a purely retinotopic adaptation. In two different saccadic paradigms, no significant effect was observed after spatiotopic adaptation. No interocular transfer was found. In a third experiment, the effect of the luminance signal on adaptationbased duration compression was investigated using luminance-modulated and isoluminant stimuli. It was shown that the apparent duration compression following temporal frequency adaptation is specific to luminance-modulated stimuli and that the effect disappears at isoluminance. The differences in visibility between luminance-modulated and isoluminant stimuli could not explain the discrepancy. At isoluminance, duration compression was recovered for chromatic backgrounds. The final experiments investigated the effect of simultaneous surrounds on the perceived duration of inner patches. It was found that perceived duration of a mid-temporal frequency counterphase modulated flicker is almost significantly expanded if embedded within a high temporal frequency context; whereas a low temporal frequency context can only induce a mild expansion. In an adaptation paradigm, counterphase modulated flicker was found to induce smaller duration compression compared to drifting stimuli. These results provide further evidence for a difference between mechanisms modulating duration and temporal frequency.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available