Examining the Self-Reference Effect in Healthy Aging and Amnestic Mild Cognitive Impairment
Carson, Nicole Rosanna
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This dissertation investigates the Self-Reference Effect (SRE), enhanced memory for self-related information, in terms of its ability to enhance episodic memory in healthy aging and amnestic Mild Cognitive Impairment (aMCI). Additionally, the persistence of the SRE over time is examined in healthy aging and aMCI. The dissertation furthermore explores the ability of self-referential processing to enhance recollection memory in healthy aging and aMCI (known as the Self-Reference Recollection Effect), and whether stimuli valence influences memory in these populations. In Experiment 1, the SRE was studied in healthy aging and aMCI for trait adjectives, the most common form of stimuli utilized in SRE research. Results indicated that while the healthy aging group benefitted from self-referential encoding in terms of overall recognition memory and enhanced recollection, the aMCI group did not specifically benefit from self-referential processing over that of semantic encoding, indicating an effect of deep encoding in general. Stimuli valence was not shown to influence memory in either group. In Experiment 2, the SRE was investigated in healthy aging and aMCI for narrative information, thought to be more meaningful than individual trait adjective words. A test of narrative cued recall showed an SRE in healthy aging but not in aMCI. The SRE was found in both populations on a test of recognition. Additionally, while self-referential encoding improved recollection for narrative material in healthy aging, it did not show effects over and above that of semantic encoding in aMCI. Cued recall was higher for negative versus positive details in both groups, however there was no influence of valence on recognition of narrative details. Experiment 3 examined whether the benefits of self-referential processing continue to appear following a one-week delay in healthy aging. The SRE for both trait adjectives and narrative information was shown to persist following the delay, and improved recollection also remained present for self-referenced material. Cued recall of narrative details did not show extra benefit for self-referenced material at follow-up testing. Enhanced recall was specifically evident for negatively valenced narrative details, as was improved recollection. Experiment 4 investigated whether the persistence of the SRE found in Experiment 3 in healthy aging extends to those with aMCI. Results indicated that while individuals with aMCI did show a mnemonic advantage for self-referenced narrative material following a one-week time delay, they still benefitted from deep encoding in general. Recollection similarly continued to improve with deep encoding processes following a delay. In cases where valence preferences were found, they were in the direction of a negativity bias. The dissertation findings presented here extend previous research and uniquely contribute to our understanding of the SRE and deep encoding strategies in healthy aging and in aMCI by demonstrating the following: 1) The SRE reliably extends to narrative information; 2) The SRE specifically advantages memory over time in healthy aging; 3) In aMCI, observation of an SRE may be dependent on the type of information to be encoded (for example, trait adjective versus narrative information); and 4) Deep encoding strategies in general appear to benefit memory over time in aMCI.