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Abstract

ABSTRACT

The following set of experiments investigates the fundamental mechanism proposed to underlie interval timing and addresses a key question in timing research pertaining to the underlying functional architecture. Numerous models have been proposed in an attempt to illustrate and explain timing performance, some based on dedicated features employing a specialised mechanism, whilst others suggest that time perception is inherent in neural dynamics. An influential set of models posit that the brain contains a mechanism akin to a mental stopwatch which can be started, stopped and paused at will. This premise was tested in the first experimental chapter, the expected decline in performance was calculated in line with model predictions. The observed deterioration significantly exceeded the calculated predictions indicating that human timing is not akin to that of a ‘stopwatch’ when timing short durations and is incongruent with the predictions of a pacemaker accumulator type mode that can be paused at will. Psychophysical methods have revealed that interval timing conforms to a fundamental property in sensory processing known as Weber’s Law. Lawful relationships such as these are important because they inform and constrain models of human interval timing. The adherence to this property was investigated across a range of durations using two comparable tasks in the following experiment. Although violations across certain durations were observed, these were not mirrored in both the utilised tasks to a statistically significant degree. The results could tentatively be argued to suggest certain constraints on the scalar model albeit a firm conclusion cannot be asserted. The second question pertaining to multimodal processing across a range of tasks and durations, indicative of the underlying architecture of interval timing, (i.e. ‘one clock or many’) was addressed via transfer of learning and correlation in the two final experiments. Perceptual learning and the generalisation to untrained durations and temporal tasks was assessed in the first of these two chapters. Training was observed to improve performance at a few of the practised durations with a more global improvement for one participant across untrained durations. Generalisation to the motor tasks from the perceptual task was observed consistently in two of the longer trained durations for all three participants pointing to a partially shared or overlapping interval timing structure. The next study further addressed some of the dichotomies reported in timing literature, with a key focus on explicit and implicit timing. Particular attention was also bestowed on timing in language: the language task based on phoneme closure duration and not overly reliant on contextual cues was observed to have a significant association with both motor and perceptual timing tasks. The results of the conducted experiments when taken together point to independent mechanisms which nonetheless possess a significant overlap.

Publication Type:	Thesis (Doctoral)
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Departments:	School of Health & Psychological Sciences > Psychology

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