No abstract

Theories of working memory often disagree on the relationships between processing and storage, particularly on how heavily they rely on an attention-based limited resource. Some posit separation and specialization of resources resulting in minimal interference to memory when completing an ongoing processing task, while others argue for a greater overlap in the resources involved in concurrent tasks. Here, we present four experiments that investigated the presence or absence of dual-task costs for memory and processing. The experiments were carried in an adversarial collaboration in which researchers from three opposing theories collaboratively designed a set of experiments and provided differential predictions in line with each of their models. Participants performed delayed recall of aurally and visually presented letters and an arithmetic verification task either as single tasks or with the arithmetic verification task between presentation and recall of letter sequences. Single- and dual-task conditions were completed with and without concurrent articulatory suppression. A consistent pattern of dual-task and suppression costs was observed for memory, with smaller or null effects on processing. The observed data did not fit perfectly with any one framework, with each model having partial success in predicting data patterns. Implications for each of the models are discussed, with an aim for future research to investigate whether some combination of the models and their assumptions can provide a more comprehensive interpretation of the pattern of effects observed here and in relevant previous studies associated with each theoretical framework.

Three experiments investigated younger (18-25 yrs) and older (70-88 yrs) adults' temporary memory for colour-shape combinations (binding). We focused upon estimating the magnitude of the binding cost for each age group across encoding time (Experiment 1; 900/1500 ms), presentation format (Experiment 2; simultaneous/sequential), and interference (Experiment 3; control/suffix) conditions. In Experiment 1, encoding time did not differentially influence binding in the two age groups. In Experiment 2, younger adults exhibited poorer binding performance with sequential relative to simultaneous presentation, and serial position analyses highlighted a particular age-related difficulty remembering the middle item of a series (for all memory conditions). Experiments 1-3 demonstrated small to medium binding effect sizes in older adults across all encoding conditions, with binding less accurate than shape memory. However, younger adults also displayed negative effects of binding (small to large) in two of the experiments. Even when older adults exhibited a greater suffix interference effect in Experiment 3, this was for all memory types, not just binding. We therefore conclude that there is no consistent evidence for a visual binding deficit in healthy older adults. This relative preservation contrasts with the specific and substantial deficits in visual feature binding found in several recent studies of Alzheimer's disease.

Relative to younger adults, older adults tend to perform more poorly on tests of both free recall and item recognition memory. The age difference in performance is typically larger for recall tasks relative to those involving recognition. However, there have been reports of comparable age-related differences in free recall and item recognition performance. Further, a differential performance cost does not necessarily mean that processes involved in recall are specifically affected by age. Here we present a meta-analysis of 36 articles reporting 89 direct comparisons of free recall and item recognition in younger and older groups of participants. Standardized effect sizes reveal that age differences are larger for recall tasks (Hedges' g = 0.89, 95% confidence intervals [0.75, 1.03]) than for recognition tasks (0.54, [0.37, 0.72]). Further, Brinley analyses of the data suggest that distinct functions are needed to relate younger and older performance for the two tasks. These functions differ in intercept pointing to a disproportionate age difference in recall relative to recognition. This is in line with theories of memory and aging which posit specific deficits in processes related to search and retrieval from memory.

There is a theoretical disagreement in the working memory literature, with some proposing that the storage and processing of information rely on distinct parts of the cognitive system and others who posit that they rely, to some extent, on a shared attentional capacity. This debate is mirrored in the literature on working memory and aging, where there have been mixed findings on the ability of older adults to perform simultaneous storage and processing tasks. We assess the overlap between storage and processing and how this changes with age using a procedure in which both tasks have been carefully adjusted to produce comparable levels of single-task performance across a sample (N = 164) of participants aged 18–81. By manipulating incentives to perform one task over the other, this procedure was also capable of disentangling concurrence costs (single- versus dual-task performance) from prioritization costs (relative payoffs for storage versus processing performance) in a theoretically meaningful manner. The study revealed a large general cost to serial letter recall performance associated with concurrent performance of an arithmetic verification processing task, a concurrence cost that increased with age. For the processing task, there was no such general concurrence cost. Rather, there was a prioritization effect in dual-task performance for both tasks, irrespective of age, in which performance levels depended on the relative emphasis assigned to memory versus processing. This prioritization effect was large, albeit with a large residual in performance. The findings place important constraints on both working memory theory and our understanding of how working memory changes across the adult lifespan.

A large body of research has clearly demonstrated that healthy ageing is accompanied by an associative memory deficit. Older adults exhibit disproportionately poor performance on memory tasks requiring the retention of associations between items (e.g., pairs of unrelated words). In contrast to this robust deficit, older adults' ability to form and temporarily hold bound representations of an object's surface features, such as colour and shape, appears to be relatively well preserved. However, the findings of one set of experiments suggest that older adults may struggle to form temporary bound representations in visual working memory when given more time to study objects. However, these findings were based on between-participant comparisons across experimental paradigms. The present study directly assesses the role of presentation time in the ability of younger and older adults to bind shape and colour in visual working memory using a within-participant design. We report new evidence that giving older adults longer to study memory objects does not differentially affect their immediate memory for feature combinations relative to individual features. This is in line with a growing body of research suggesting that there is no age-related impairment in immediate memory for colour-shape binding.

There are few examples of an extended adversarial collaboration, in which investigators committed to different theoretical views collaborate to test opposing predictions. Whereas previous adversarial collaborations have produced single research articles, here, we share our experience in programmatic, extended adversarial collaboration involving three laboratories in different countries with different theoretical views regarding working memory, the limited information retained in mind, serving ongoing thought and action. We have focused on short-term memory retention of items (letters) during a distracting task (arithmetic), and effects of aging on these tasks. Over several years, we have conducted and published joint research with preregistered predictions, methods, and analysis plans, with replication of each study across two laboratories concurrently. We argue that, although an adversarial collaboration will not usually induce senior researchers to abandon favored theoretical views and adopt opposing views, it will necessitate varieties of their views that are more similar to one another, in that they must account for a growing, common corpus of evidence. This approach promotes understanding of others’ views and presents to the field research findings accepted as valid by researchers with opposing interpretations. We illustrate this process with our own research experiences and make recommendations applicable to diverse scientific areas.

Recent theoretical development of working memory has emphasized the role of attention in several active processes supporting maintenance. Although this development is certainly welcome and has accounted for a number of phenomena, there are findings that cannot be readily accounted for through the active use of attention in refreshing or removal of information. We review these findings and suggest that, whenever the circumstances allow, participants attempt to reduce the load on attention by making use of stored concepts in long-term memory (LTM) or off-loading new configurations, forming new long-term memories. Newly formed groups and configurations in LTM constitute a list- or array-wide version of the consolidation of information into memory to prevent forgetting in a manner that reduces the need for continued attention to the material. This suggestion leads to a number of interesting questions at the behavioral and neural levels, which we also discuss.