Investigating the Relationship Between Delay and Probability Discounting: Evidence from Healthy Aging and Focal Lesion Patients

Simple item page
dc.contributor.advisorRosenbaum, R. Shayna
dc.contributor.authorMok, Jenkin Ngo Yin
dc.date.accessioned2023-10-04T10:59:52Z
dc.date.available2023-10-04T10:59:52Z
dc.date.issued2021-09
dc.date.updated2023-10-04T10:59:52Z
dc.degree.disciplinePsychology (Functional Area: Clinical Psychology)
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractEach day, we engage in complex decisions that involve weighing different reward outcomes by considering the prolonged impact (delay discounting) or risk (probability discounting) associated with our choices. Surprisingly, the nature of the relationship between delay and probability discounting remains unclear despite their interdisciplinary relevance to trait impulsivity and future-oriented thinking. The current dissertation aims to understand whether a common mechanism underlies delay and probability discounting through a neurocognitive lens. In Study 1, I examined the neural substrates affecting delay and probability discounting by assessing both decision-making tasks in individuals with vmPFC or MTL damage and in matched controls. Overall, only vmPFC patients discounted delayed rewards more steeply, but discounted probabilistic rewards more shallowly, than controls, representing a significant negative correlation in performance between the two discounting tasks. In Study 2, the relationship between delay and probability discounting was evaluated by determining if personal event cues, which are known to modulate delay discounting, also modulate probability discounting. Similar to previous studies, event cues led to shallower discounting of delayed rewards; however, this effect was significantly less pronounced in older adults compared to young adults. In contrast, event cues had little to no effect on the discounting of probabilistic rewards for both age groups. Study 3 extended the findings from the first two studies by examining whether personal event cues modulate probability discounting in vmPFC patients, who were recently shown to reduce delay discounting when presented with event cues. When presented with cues, vmPFC patients discounted probabilistic rewards more steeply than controls. Importantly, their rates of discounting with cues were aligned with the typical discounting observed in controls without cues, suggesting a modulatory effect that also reduced their risk-taking. MTL patients, like controls, showed no differences in probability discounting with and without cues. Collectively, my dissertation provides evidence against the theory that a unitary trait of discounting underlies delay and probability discounting. Nevertheless, at a neurocognitive level, this set of studies shows that the vmPFC is central to reward discounting, and within its contributions to reward valuation and episodic future thinking, may instantiate self-schematic representations to modulate delay and probability discounting.
dc.identifier.urihttps://hdl.handle.net/10315/41458
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectNeurosciences
dc.subjectCognitive psychology
dc.subjectBehavioral sciences
dc.subject.keywordsIntertemporal choice
dc.subject.keywordsDelay discounting
dc.subject.keywordsProbability discounting
dc.subject.keywordsDecision-making
dc.subject.keywordsEpisodic simulation
dc.subject.keywordsEpisodic memory
dc.subject.keywordsEpisodic future thinking
dc.subject.keywordsPatient-lesion model
dc.subject.keywordsBrain-lesions
dc.subject.keywordsHealthy aging
dc.subject.keywordsVentromedial prefrontal cortex
dc.subject.keywordsvmPFC
dc.subject.keywordsMedial temporal lobe
dc.subject.keywordsMTL
dc.subject.keywordsHippocampus
dc.subject.keywordsSelf-schema
dc.subject.keywordsImpulsivity trait
dc.subject.keywordsRisk-taking
dc.titleInvestigating the Relationship Between Delay and Probability Discounting: Evidence from Healthy Aging and Focal Lesion Patients
dc.typeElectronic Thesis or Dissertation

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Mok_JenkinNgoYin_2021_PhD.pdf
Size:
2.53 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 2 of 2
No Thumbnail Available
Name:
license.txt
Size:
1.87 KB
Format:
Plain Text
Description:
Download
No Thumbnail Available
Name:
YorkU_ETDlicense.txt
Size:
3.39 KB
Format:
Plain Text
Description:
Download

Collections

Psychology (Functional Area: Clinical Psychology)

All items in the YorkSpace institutional repository are protected by copyright, with all rights reserved except where explicitly noted.