Cortical thickness in the right inferior frontal gyrus mediates age-related performance differences on an item-method directed forgetting task

Does stereotype threat influence age-related differences on directed forgetting tasks?

Objectives

The Directed Forgetting paradigm has proven to be a powerful tool to explore motivated forgetting in the lab. Past work has shown that older adults are less able to intentionally suppress information from memory relative to younger adults, which is often attributed to deficits in inhibitory abilities. Instructions in traditional Directed Forgetting tasks contain terms that may elicit stereotype threat in older adults, which may negatively impact memory. Here, we tested whether the instructions in a Directed Forgetting task affected older adults' ability to appropriately control the contents of memory.

Methods

In two experiments that differed in the number of words presented (30 vs. 48 items), younger and older adults were randomized into one of four crossed Conditions of a Directed Forgetting task. At encoding, participants were either instructed to remember/ forget items, or to think about/not think about items. At test, they were either asked whether the memory probe was old or new, or whether they had seen it before (yes/no). Each experiment contained data from 100 younger (18- 40 years) and 98 older (60+ years) adults, with ~25 participants per Condition. All participants were recruited from Prolific and tested online.

Results

In neither Experiment 1 nor Experiment 2 did we find evidence of a stereotype threat effect, or age-related effects of directed forgetting. We did find that performance for to-be-forgotten items was worse in conditions with encoding instructions that contained words that might trigger stereotype threat relative to conditions that did not contain such words: when explicitly told to forget items, both older and younger adults forgot more items than did participants who were cued to not think about the words and put them out of mind. However, we found no such difference across the two different remember instructions: regardless of whether participants were told to remember or to think about items, recognition memory for to be retained items was high. The pattern of results across the two experiments was similar, except, not surprisingly, participants performed worse in Experiment 2 than Experiment 1. Interestingly, we found that higher accuracy for to be remembered items was associated with a more positive outlook of one's own memory relative to others.

Discussion

These results suggest that directed forgetting may not always be impaired in older adults.

Uncertainty drives exploration of negative information across younger and older adults

Although individuals generally avoid negative information, recent research documents that they voluntarily explore negative information to resolve uncertainty. However, it remains unclear (a) whether uncertainty facilitates exploration similarly when exploration is expected to lead to negative, neutral, or positive information, and (b) whether older adults seek negative information to reduce uncertainty like younger adults do. This study addresses the two issues across four experimental studies (N = 407). The results indicate that individuals are more likely to expose themselves to negative information when uncertainty is high. In contrast, when information was expected to be neutral or positive, the uncertainty surrounding it did not significantly alter individuals' exploration behavior. Furthermore, we found that uncertainty increased the exploration of negative information in both older and younger adults. In addition, both younger and older adults chose to explore negative information to reduce uncertainty, even when there were positive or neutral alternatives. In contrast to the age-related similarities in these behavioral measures, older adults demonstrated reduced scores in questionnaires on sensation seeking and curiosity, relative to their counterparts who were younger. These results suggest that information uncertainty has a selective facilitation effect on exploration for negative information and that normal aging does not alter this tendency, despite age-related reductions in self-reported measures of personality traits relevant to information seeking.

Older adults compensate for switch, but not mixing costs, relative to younger adults on an intrinsically cued task switching experiment

Introduction

Aging negatively impacts the ability to rapidly and successfully switch between two or more tasks that have different rules or objectives. However, previous work has shown that the context impacts the extent of this age-related impairment: while there is relative age-related invariance when participants must rapidly switch back and forth between two simple tasks (often called "switch costs"), age-related differences emerge when the contexts changes from one in which only one task must be performed to one in which multiple tasks must be performed, but a trial-level switch is not required (e.g., task repeat trials within dual task blocks, often called "mixing costs"). Here, we explored these two kinds of costs behaviorally, and also investigated the neural correlates of these effects.

Methods

Seventy-one younger adults and 175 older adults completed a task-switching experiment while they underwent fMRI brain imaging. We investigated the impact of age on behavioral performance and neural activity considering two types of potential costs: switch costs (dual-task switch trials minus dual-task non-switch trials), and mixing costs (dual-task non-switch minus single-task trials).

Results

We replicated previous behavioral findings, with greater age associated with mixing, but not switch costs. Neurally, we found age-related compensatory activations for switch costs in the dorsal lateral prefrontal cortex, pars opercularis, superior temporal gyrus, and the posterior and anterior cingulate, but age-related under recruitment for mixing costs in fronto-parietal areas including the supramarginal gyrus and pre and supplemental motor areas.

Discussion

These results suggest an age-based dissociation between executive components that contribute to task switching.

Value-directed memory selectivity relies on goal-directed knowledge of value structure prior to encoding in young and older adults

People are generally able to selectively attend and remember high-value over low-value information. Here, we investigated whether young and older adults would display typical value-based memory selectivity effects for to-be-learned item-value associations when goal-directed information about the meaning of associated values was presented before and after encoding. In two experiments, both young and older adults were presented with one (Experiment 1) or multiple (Experiment 2) lists of words that were arbitrarily paired with different numerical values (e.g., "door-8") or font colors (e.g., "door" presented in red), which indicated each word's value. In Experiment 1, participants were told that the numerical value indicated the relative importance of each item either before they studied the list (preencoding), after they studied it (postencoding), or not at all (no value control instructions). Older adults were significantly more selective in the preencoding condition relative to the other conditions, whereas younger adults were not selective in any condition on this single-list (numerical) value task of Experiment 1. In Experiment 2, young and older adults were tested on four additional lists of both pre- and postencoding trials each after studying and recalling four lists of words without any value instructions. Results from Experiment 2 revealed that both young and older adults selectively prioritized high-value words on the preencoding trials, but not on postencoding trials, on this color-based categorical (low-medium-high) value task. The present study highlights a critical role of goal-directed knowledge of value-based instructions prior to encoding to facilitate typically observed value-directed memory selectivity for important information. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Principal component analysis suggests multiple dimensions of memory inhibition that are differentially affected by age

Background

Cognitive inhibition is among the executive functions that decline early in the course of normal aging. Failures to be able to inhibit irrelevant information from memory may represent an essential factor of age-associated memory impairment. While a variety of elaborate behavioral tasks have been developed that presumably all index memory inhibition, the extent to which these different tasks measure the same underlying cognitive construct that declines with age has not been well explored.

Methods

In the current study, 100 and 75 cognitively healthy younger (n = 71; age = 30.7 ± 5.4 years, 56.7% female) and older (n = 104, age = 69.3 ± 5.9 years, 66.2% female) adults with equivalent educational attainment performed three computer-based memory inhibition tasks: the Retrieval Induced Forgetting task, the Suppress task, and the Directed Forgetting task. We conducted a principal component analysis using scores derived from different components of these tasks to explore whether and how the tasks relate to one another. We further investigated how age, sex and education, along with, in a subsample of the participants, a neuropsychological measure of episodic memory, impacted both the task scores individually, and the principal components derived from the exploratory analysis.

Results

We identified 3 distinct sources of variability which represent potentially independent cognitive processes: memory retrieval facilitation, and two memory inhibition processes that distinguished themselves by the degree of volitional initiation of memory suppression. Only the memory retrieval component correlated with a neuropsychologically-derived episodic memory score, and both memory inhibition principal components were age dependent.

Conclusion

Our findings provide support for a distinction in memory suppression processes between those 'instructed' to be performed and those which happen without explicit instruction. This distinction adds nuance to the dichotomous classification of controlled vs. automatic inhibitory mechanisms, which have been shown in previous work to vary as a function of the degree of frontal involvement. Our findings further demonstrate that while both of these measures of inhibition were affected by age, the episodic memory component was not, suggesting that inhibitory impairments may precede memory deficits in healthy aging.