EXPLORING RELATIONSHIPS BETWEEN TEMPORAL PROCESSING DEFICITS AND PSYCHOSIS USING THE PEAK INTERVAL TASK
Persons with schizophrenia commonly report distortions in their subjective experience of time. Mirroring these subjective experiences are findings that persons with schizophrenia are both less accurate, and precise, in detecting time in the range of seconds to minutes (interval timing). However, the mechanisms which give rise to these deficits in interval timing remain unknown as previous studies have relied on paradigms which do not allow us to easily dissect the influence of timing processes from memory, and decision making, on task performance. In addition, these studies have typically depended on samples who are taking antipsychotic medications making it difficult to determine whether deficits in interval timing are related to psychosis specifically or the consequences of antipsychotic medication. To address these concerns, I developed an online peak interval task. The peak interval task is a gold standard paradigm in which participants are instructed to learn, and reproduce, an unknown duration of time; analysis of trial-by-trial reproductions of this duration allows for the relative influence of internal clock, memory, and decision-making processes on temporal processing to be teased apart. In a series of studies, I tested the validity of this newly developed task and then tested the extent to which temporal processing deficits could predict psychosis-risk status in a non-clinical sample. In Experiment 1, 524 undergraduate students completed an online peak interval task in which they were asked to learn, and reproduce, two durations of time (6s and 20s) over multiple trials. Performance on this task was compared to that of 14 rats completing an analogous task. Data from humans broadly aligned with the general principles of interval timing, attesting to the validity of the paradigm. While the general pattern of performance was similar in rats and humans, there were some quantitative differences: the human sample was more accurate and precise than the rodents. This improved performance was related to a greater influence of memory and decision-making processes on performance. In Experiment 2, I recruited 61 individuals who were classified as at-risk for psychosis, had no formal psychotic disorder, and were not taking antipsychotic medications. The peak interval performance of these individuals was compared against 90 randomly selected controls. Timing accuracy and precision in reproducing the 6s duration predicted risk-group membership. Additionally, timing accuracy in reproducing the 6s duration explained significant variance in the presence of positive, and negative, schizotypal traits across the sample. These findings suggest that disruptions in temporal processing may be a risk marker for schizophrenia which may help illuminate illness mechanisms.
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- In Collections
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Electronic Theses & Dissertations
- Copyright Status
- Attribution 4.0 International
- Material Type
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Theses
- Authors
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Roberts, Dominic Trevor
- Thesis Advisors
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Thakkar, Katharine
- Committee Members
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Johnson, Alex
Moser, Jason
Ingersoll, Brooke
- Date Published
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2025
- Subjects
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Social sciences
Clinical psychology
- Program of Study
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Psychology - Doctor of Philosophy
- Degree Level
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Doctoral
- Language
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English
- Pages
- 71 pages
- Permalink
- https://doi.org/doi:10.25335/v8hs-zc83