Title:
The influence of valid and invalid context memory cues at encoding
The influence of valid and invalid context memory cues at encoding
Author(s)
Strunk, Jonathan
Advisor(s)
Duarte, Audrey
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Abstract
Previous episodic memory studies have found that neural activity preceding a to-be-encoded event can reflect subsequent memory performance. This neural activity is thought to reflect the preparatory engagement of cognitive processes related to the specific task characteristics. It is currently unknown if the preparatory activity reflects a benefit to successful encoding or is epiphenomenal; such that trials in which the participant engages in preparatory processes are also trials for which the participant is actively engaged and more likely to successfully encode. Numerous attentional orienting and detection studies find that accurate preparation improves performance by biasing the relevant neural regions and processes. These studies also show that inaccurate preparation can bias competing regions and processes which lead to impairments in performance. This dissertation directly tests the influence of preparation on successful encoding, by manipulating the accuracy of preparation. If preparation directly influences processing the to-be-encoded information, then there should be a benefit to accurately preparing with trial relevant information and a cost to preparation with inaccurate information. But, if preparation is solely epiphenomenal, then the utility of preparation should not influence successful encoding. In the dissertation, I paired items with one of four context scenes during an associative memory task. On each trial, a prestimulus cue was presented that indicated either a context scene with a text label or an uninformative neutral label. The context label cues predicted which scene would be paired with the item. For valid cue trials the cued scene was presented with the item, and for invalid trials the cued scene was not the same as the presented scene. In order to encourage strategic use of the cues, an additional required cue condition was included where a scene was not presented with the item. This paradigm allows for the assessment of preparation without task or stimulus confounds, as it directly assesses accurate and inaccurate preparation while hold task and stimulus characteristics constant within the cue – stimulus interval across cue conditions. Before the encoding task, a familiarization task was used to associate specific context cue labels with specific scene images. During retrieval, old and new items were intermixed, and participants indicated if the item was new or selected the associated scene. A second question asked for their confidence in the retrieval decision. Neural oscillations were used to assess neural activity related to successful subsequent context memory performance. Overall, I found that accurate preparation improved context memory performance and that invalid cues placed greater demands on successfully encoding the correct context. In addition, inaccurate preparation interfered with processing the presented scene compared to trials with a valid cue. During context memory retrieval, the results suggest that participants who did not resolve the interference from the invalid cue at encoding had worse context memory performance. Thus, the utility of preparation during encoding has a direct impact on memory performance.
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Date Issued
2018-10-24
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Dissertation