Decisions are based on multiple sources of information. For example, sensory information encoding environmental features may be combined with prior experience to bias judgements in visual behaviour. With the goal of characterizing the rules by which sensory and non-sensory variables combine to direct saccade selection processes monkeys were trained in a visual search task where the discriminability of a visual target and reward outcome for correct foveation varied systematically. Target discriminability was manipulated across three levels of luminance contrast while reward was manipulated by 'tagging' a spatial location such that target foveation at the tagged location yielded one, two or four times the liquid reward available at all other locations. The location and discriminability of the search target amongst seven distractor stimuli varied randomly from trial-to-trial while the magnitude of reward at the tagged location was fixed for each experimental block.
Reward was found to have a large effect on search behaviour when target discriminability was low, but as discriminability increased, the effect of reward diminished. More specifically, reward increased choice probability and reduced the latency of saccades to target and distractor stimuli appearing in the tagged location. Together, the results suggested the effects of reward and luminance on saccade selection were dependent on one another.
To characterize the nature of this interaction search psychophysics were couched in saccade selection processes using signal detection theory. Signals carrying target and distractor related information were modelled and taken to capture an actual discrimination process implemented by the brain. It was found that a response bias in saccade selection processes could largely reproduce monkey choice behaviour for both correct and incorrect trials. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2010-08-03 22:22:15.825
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/5957 |
| Date | 06 August 2010 |
| Creators | Warfe, Michael |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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