Attended objects are perceived differently than unattended objects. Spatial attention is consistently associated with an enhancement in spatial resolution. However, the relation between spatial attention and temporal resolution is not as straightforward. Some studies have shown that attention enhances temporal resolution, and others have shown that attention degrades temporal resolution. The motivation of the present work was to investigate the source of this discrepancy. In particular, the research herein examines the
hypothesis that attention degrades temporal resolution when the target stimuli are easily integrated (i.e., according to the Gestalt principles of grouping), and that attention enhances temporal resolution when the targets are easy to perceptually segregate. Temporal resolution was assessed by the mean just noticeable difference (the minimum temporal interval in milliseconds required by observers to perform the task at 75%
accuracy) in a visual temporal order judgment (TOJ) task. Trials involved the
presentation of two targets, at randomly varying stimulus onset asynchronies, and observers reported which one they perceived first. The primary research questions concerned the effect of perceptual grouping on temporal resolution, and the influence of attention on that relation. Grouping processes were manipulated using a variety of Gestalt principles and attention was investigated under conditions of automatically-and voluntarily-driven orienting. Three main findings emerged: temporal resolution is worse
for grouped than ungrouped targets; attention modulates the effect of grouping on temporal resolution on a continuum - strong grouping effects produce large impairments on temporal resolution, and weaker grouping effects produce smaller impairments; and automatic and voluntary spatial orienting affect the relation between grouping and temporal resolution differently - automatic orienting augments the relation, while
voluntary orienting does not. I conclude that the discrepant findings in the previous research are due to object-based factors pertaining to the target stimuli and propose an object-based theory of temporal perception. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16642 |
| Date | 09 1900 |
| Creators | Nicol, Jeffrey R. |
| Contributors | Shore, D.I., Psychology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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