Aging and directed forgetting: Evidence for an associative deficit but no evidence for an inhibition deficit.

Abstract

Intentional forgetting aims to prevent unwanted information from being stored in long-term memory. Surprisingly, past research has shown that, relative to younger adults, older adults recall and recognize more to-be-forgotten information. It has been suggested that this occurs because older adults have a deficient ability to inhibit information. In two experiments, we examined memory differences between older and younger adults in an item-method directed forgetting task. Participants viewed words one at a time during a study phase, each followed by a cue to remember (R) or to forget (F). In Experiment 1, participants' later recognition of both types of items was assessed, followed by a separate source discrimination test for the cue that had been associated with each word at study. In Experiment 2, memory was assessed using a threeresponse recognition test, indicating whether each word was either new or previously studied and, if previously studied, whether it was associated with an R cue or an F cue. In both experiments, older and younger adults recognized more to-be-remembered items than to-be-forgotten items, the typical directed forgetting effect (DFE). Contrary to past reports, older adults did not remember more to-be-forgotten items than did younger adults, inconsistent with an inhibitory deficit. Older adults were, however, less accurate than younger adults in identifying cue associations for both R and F items, consistent instead with an associative memory deficit. Public Significance StatementIntentional forgetting allows us to update the contents of our memory with the most current information. Previous research suggested that older adults are not as efficient as younger adults in filtering out stored information that is no longer relevant (e.g., an expired phone number). Here, we demonstrate that, in fact, older adults can intentionally forget information just as well as younger adults. Older adults, however, were less able to form the associations between necessary for identifying which information should be remembered and which should be forgotten.

Reward motivation more consistently modulates memory for younger compared to older adults in a directed forgetting task.

“…Our general findings are similar to a recently published itemmethod directed forgetting study with an online sample who also reported an overall directed forgetting effect, but no age-related deficits in forgetting compared to younger adults (Tanberg et al, 2022). There are other empirical exceptions to age-related deficits in forgetting, including when the older participant is not personally responsible for remembering the information, TBF information is not goal relevant, or TBF is presented in a more applied context (e.g., McGillivray & Castel, 2017;Murphy & Castel, 2022).…”

“…The cognitive mechanisms used in an item-method directed forgetting task, particularly in older age, are still debated. Explanations include differential encoding for TBR versus TBF items (Basden, 1996; Basden et al, 1993; Bjork, 1989; Bjork & Woodward, 1973; MacLeod, 1989, 1999, 2012; Sahakyan et al, 2008; Titz & Verhaeghen, 2010) particularly attentional inhibition and suppression of TBF information (Rizio & Dennis, 2013, 2014; Van Hooff et al, 2009; Zacks et al, 1996, 2000), cognitive load and working memory capacity limits (Popov et al, 2019), and deficits in associative binding in older age (Tanberg et al, 2022), as well as evidence that the mechanisms or strategy may change depending on the specifics of the experimental design (Lee, 2012; Sego et al, 2006). The strategies used to remember and forget may be different and may not interact with reward in the same way, but we did not design our experiments to test these different mechanisms.…”

“…According to the influential inhibitory theory (Hasher & Zacks, 1988), age-related declines in control over inhibitory memory processes that suppress further processing of TBF items at encoding is the underlying cause of age-related difficulties with intentional forgetting in item-level directed forgetting tasks (Gallant et al, 2018; Rizio & Dennis, 2013, 2014; Sahakyan et al, 2008; Titz & Verhaeghen, 2010; Van Hooff et al, 2009; Zacks et al, 1996, 2000). Empirical evidence indicates that declines in attentional inhibition and suppression of TBF information (Rizio & Dennis, 2013, 2014; Van Hooff et al, 2009; Zacks et al, 1996, 2000) leads to difficulty forgetting in older age, while other evidence suggests that declines in working memory capacity limits (Popov et al, 2019) or deficits in associative binding (Tanberg et al, 2022) are responsible for age-related deficits in intentional forgetting.…”