Adult age differences in subjective context retrieval in dual-list free recall

Abstract

Age-related episodic memory deficits imply that older and younger adults differentially retrieve and monitor contextual features that indicate the source of studied information. Such differences have been shown in subjective reports during recognition and cued recall as well as process estimates derived from computational models of free recall organisation. The present study extends the subject report method to free recall to characterise age differences in context retrieval and monitoring, and to test assumptions from a context-based computational model. Older and younger adults studied two lists of semantically related words and then recalled from only the first or second list. After each recall, participants indicated their subjective context retrieval using remember/know judgments. Compared to younger adults, older adults showed lower recall accuracy and subjective reports of context retrieval (i.e., remember judgments) that were less specific to correct recalls. These differences appeared after first-recall attempts. Recall functions conditioned on serial positions were more continual across correct recalls from target lists and intrusions from non-target lists for older than younger adults. Together with other analyses of context retrieval and monitoring reported here, these findings suggest that older adults retrieved context less distinctively across the recall period, leading to greater perceived similarity for temporally contiguous lists.

Keywords: Aging; context; episodic memory; free recall; recollection.

Figure 1. Experimental Design Schematic

Note. Schematic of the procedure for the dual-list free recall task. Participants completed 3 blocks of four trials (12 trials total) with each block including two trials for each of the recall conditions. Although the schematic above only includes three exemplars per list, the actual experiment included four exemplars from three categories per list (12 words total). Words were presented within their respective categories above to demonstrate the list composition but were randomized within lists for the experimental trials.

Figure 2. Correct Recalls and Intratrial Intrusions Overall and for Remember/Know Judgments

Note. Mean frequencies of correct recalls (top panels) and intratrial intrusions (bottom panels) for all responses (left panels) and joint probabilities of responses given remember (middle panels) and know judgments (right panels) in each recall list condition for younger and older adults. Colored points show individual participant frequencies, the widths of the half violin plots show the proportion of data at each frequency, box plots show medians and interquartile ranges, white diamonds show model-estimated frequencies, and corresponding error bars are 95% confidence intervals.

Figure 3. Serial Position Curves for Correct Recalls and Intratrial Intrusions

Note. Smoothed serial position curves displaying model-estimated mean frequencies of correct recalls and intratrial intrusions as a function of input position for tests of List 1 (top panels) and List 2 (bottom panels) for younger and older adults. The gray shaded box highlights the connection between correct recalls from the last serial position and intratrial intrusions from the first serial position (Recall List 1; top panels) and intratrial intrusions from the last serial position and correct recalls from the first serial position (Recall List 2; bottom panels). Error bars are 95% confidence intervals.

Figure 4. Serial Position Curves for Correct Recalls Conditionalized on Remember/Know Judgments

Note. Smoothed serial position curves displaying model-estimated mean frequencies of correct recalls as a function of input position conditionalized on remember (darker points) and know judgments (lighter points) for tests of List 1 (left panels) and List 2 (right panels) for younger and older adults. The probabilities for the remember and know functions sum to the overall probabilities for correct recalls displayed in Figure 3. Error bars are 95% confidence intervals.

Figure 5. Probability of First Recall Curves

Note. Smoothed probability of first recall curves displaying model-estimated mean frequencies of first-recalled items as a function of input position for tests of List 1 (left panel) and List 2 (right panel) for younger and older adults. Error bars are 95% confidence intervals.

Figure 6. Probability of First Recall Curves Conditionalized on Remember/Know Judgments

Note. Smoothed probability of first recall curves displaying model-estimated mean frequencies of first-recalled items as a function of input position conditionalized on remember (darker points) and know judgments (lighter points) for tests of List 1 (left panels) and List 2 (right panels) for younger and older adults. The probabilities for the remember and know functions sum to the overall probabilities displayed in Figure 5. Error bars are 95% confidence intervals.

Figure 7. Output Profiles for Correct Recalls and Intratrial Intrusions

Note. Output profiles displaying model-estimated mean output frequencies of correct recalls (circles) and intratrial intrusions (triangles) for tests of List 1 (left panel) and List 2 (right panel) for younger and older adults. Error bars are 95% confidence intervals.

Figure 8. Output Profiles for Remember-Correct Recalls

Note. Output profiles displaying model-estimated mean output frequencies of correct recalls conditionalized on remember judgments for tests of List 1 (left panels) and List 2 (right panels). Error bars are 95% confidence intervals.