An Investigation into the Mechanisms Underlying Mnemonic Precision

Mnemonic precision refers to the degree of fidelity with which we represent the details of our past experiences. Maintaining a high level of mnemonic precision allows us to distinguish between similar experiential events. Across three chapters, this thesis examines how mnemonic precision declines over time, how we might improve mnemonic precision during learning, and how the inference of perceptual details differs in a special population of people that do not experience vivid mental imagery.In Chapter One, we investigated the decline of mnemonic precision over short durations in a continuous recognition task. The ability to discriminate between studied and similar lure items was high when memory for a studied item was probed immediately after its initial presentation. However, discrimination abilities sharply declined when a single item intervened between the initial presentation of a studied item and the subsequent memory probe. Moreover, the magnitude of this decline was modulated by the similarity between studied and similar lure items. In Chapter Two, we investigated if mnemonic precision could be improved by emphasizing the differences between similar objects during encoding. During encoding, participants were encouraged to compare the features between similar objects as they studied them. We found that mnemonic discrimination was improved after comparing features between objects during encoding. Contrary to our expectations, these benefits occurred not only when similar objects were compared, but also when non-similar objects were compared, suggesting that the comparison of features during learning facilitates the encoding of object features at a high level of detail, irrespective of the difficulty of the comparison. Finally, in Chapter Three, we investigated how visual processing might differ between aphantasics—individuals who lack mental imagery—and those who have normal mental imagery. Specifically, we examined perceptual pattern completion, the process that enables us to recognize an entire object from a partial stimulus, and asked if this process is differentially impacted by visual disruption in aphantasics. We find that while aphantasics have intact pattern completion, their visual processing is more vulnerable to disruption. Together, these studies provide insight into the mechanisms of mnemonic precision and the relationship between pattern completion and mental imagery.

Department dc:contributor.department

Psychology

Year dc:date.issued

2024

Author dc:creator

• Loo, Corey Thomas

Advisor dc:contributor.advisor

• Buchsbaum, Bradley R

• aphantasia
• memory
• mnemonic precision
• pattern completion
• pattern separation

Handle dc:identifier.uri

http://hdl.handle.net/1807/140752

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/140752