Aging and Feature-Binding in Visual Working Memory: The Role of Verbal Rehearsal

Age-related decline in ability to bind and remember conjunctions of features has been proposed as an explanation for the pronounced decline of visual working memory (WM) in healthy aging. However, evidence that older adults exhibit greater visual feature-binding deficits than younger adults has been mixed. Binding deficits in older adults are often observed using paradigms with easy-to-label features. Labeling and rehearsing single features may result in apparent binding deficits if older adults rely on comparatively intact verbal memory to compensate for declining visual WM. This strategy would be more useful for single features (e.g., red), than for conjunctions of features (e.g., red triangle), which are more cumbersome to rehearse, and thus visual feature-binding paradigms that do not prevent verbal strategies may unintentionally measure verbal load differences. Across 3 experiments (total N = 150), we investigated the role of verbal rehearsal by manipulating ease of stimulus labeling for visually presented single features and conjunctions of 2 features. Overall, visual memory for difficult-to-label, noncategorical, visual information appeared especially limited for older adults, likely because it impedes engagement of other systems. such as verbal WM or long-term memory. Therefore, comparing younger- and older-adult task performance may not straightforwardly reveal age-related visual WM decline, but instead reflect applications of different strategies that tap different cognitive mechanisms. We discuss implications for the feature-binding literature and the wider visual WM literature.