The Mid-Career Award

The Working Memory Model and the relationship between immediate serial recall and immediate free recall

The effects of speech-based variables on the immediate serial recall (ISR) task constitute fundamental evidence underpinning the concept of the Phonological Loop component of Working Memory. Somewhat surprisingly, the Phonological Loop has yet to be applied to the immediate free recall (IFR) task although both tasks share similar memoranda and presentation methods. We believe that the separation of theories of ISR and IFR has contributed to the historical divergence between the Working Memory and Episodic Memory literature. We review more recent evidence showing that the two tasks are approached by participants in similar ways, with similar encoding and rehearsal strategies, and are similarly affected by manipulations of word length, phonological similarity, articulatory suppression/concurrent articulation, and irrelevant speech/sound. We present new analyses showing that the outputs of the two tasks share similar runs of successive items that include the first and last items- which we term start- and end-sequences, respectively-that the remaining residual items exhibit strong recency effects, and that start- and end-sequences impose constraints on output order that help account for error transposition gradients in ISR. Such analyses suggest that similar mechanisms might convey serial order information in the two tasks. We believe that recency effects are often under-appreciated in theories of ISR, and IFR mechanisms could generate error transpositions. We hope that our review and new analyses encourage greater theoretical integration between ISR and IFR and between the Working Memory and Episodic Memory literature.

Is variability in working memory capacity related to differences in the reactivation of memory traces? A test based on the time-based resource sharing (TBRS) model

Working memory performance depends on reactivating memory traces, by rapidly switching between refreshing item representations and performing concurrent cognitive processing (time-based resource sharing (TBRS) account). Prior research has suggested that variation in the effectiveness of this process could be a plausible source of developmental changes in working memory capacity. This could conceivably extend to adults, potentially bridging the barrier between developmental and adult experimental research and providing a possible functional role for attention control and processing speed in working memory tasks. The present work was designed to replicate the finding of developmental differences in reactivation in children, and to test whether the same process could be related to individual differences in adults. Experiment 1 confirmed the finding of more effective reactivation for 14-year-old children than for 8-year-old children. Experiment 2 using the same task in adults manipulated the feasibility of reactivation within an experimental-correlational approach, and failed to find more effective reactivation for individuals with high working memory capacity, contrary to our predictions. Overall, our results support the role of reactivation as defined by the TBRS model as an important process in working memory tasks, and as a possible source of developmental increase in working memory capacity; however, they rule out the possibility that adult individual differences in the effectiveness of this process are a major cause of variability in working memory capacity, suggesting that differences between adults are of a different nature.

Speech production factors and verbal working memory in children and adults with developmental language disorder

Verbal working memory (VWM) deficits are common in individuals with developmental language disorder (DLD) but are not well understood. This study evaluated how both memory and language production factors influence VWM performance in children and adults with DLD, focusing on the influence of serial position, phonological activation (PA), and lexical frequency. Participants were 30 children with DLD and 26 with typical language (TL), and 21 adults with DLD and 23 with TL. The participants completed a listening span task in which they were asked to recall the final words of sentences in sets of increasing size. Responses (dependent variable) were coded as correct, incorrect, or no response. Final words were coded for frequency, serial position within the set, and PA (number of occurrences of the initial phoneme, vowel, and whole word in the task). These variables, along with age and language status, were entered as predictors in mixed-effects multinomial regression models. Extreme serial position, greater PA, and higher frequency reduced incorrect and no responses. These effects were attenuated for the DLD group, and the effect of greater PA varied with set size. The findings suggest that for individuals with DLD, VWM performance is affected by more limited effective language experience and by the dynamic task demands.

The development of working memory spatialization revealed by using the cave paradigm in a two-alternative spatial choice

When Western participants are asked to keep in mind a sequence of verbal items, they tend to associate the first items to the left and the last items to the right. This phenomenon, known as the spatial-positional association response codes effect, has been interpreted as showing that individuals spatialize the memoranda by creating a left-to-right mental line with them. One important gap in our knowledge concerns the development of this phenomenon: when do Western individuals start organizing their thought from left to right? To answer this question, 274 participants in seven age groups were tested (kindergarten, Grades 1, 2, 3, 4, and 5, and adults). We used a new protocol meant to be child-friendly, which involves associating two caves with two animals using a two-alternative spatial forced choice. Participants had to guess in which cave a specific animal could be hidden. Results showed that it is from Grade 3 on that participants spatialize information in working memory in a left-to-right fashion like adults.

No Evidence That Articulatory Rehearsal Improves Complex Span Performance

It is usually assumed that articulatory rehearsal improves verbal working memory. Complex span is the most used paradigm to assess working memory functioning; yet, we still lack knowledge about how participants rehearse in this task, and whether these rehearsals are beneficial. In Experiment 1, we investigated the patterns of naturally occurring overt rehearsals in a complex span task requiring processing of a non-verbal distractor task. For comparison, another group of participants completed a matched simple span task with an unfilled delay in between the memoranda. Time permitting, participants rehearsed the memory list in forward serial order, a strategy known as cumulative rehearsal. The degree of cumulative rehearsal was correlated with recall accuracy in both span tasks. Rehearsal frequency was, however, reduced in complex span compared to simple span. To assess the causal role of rehearsal in complex span, we trained a group of participants in a cumulative rehearsal strategy in Experiment 2. This instruction substantially increased the prevalence of cumulative rehearsals compared to a control group. However, the increase in cumulative rehearsal did not translate into an increase in recall accuracy. Our results provide further evidence that rehearsal does not benefit working memory performance.

Modeling the Relations Among Sustained Attention, Short-Term Memory, and Language in Down Syndrome

Sustained attention (SA) and short-term memory (STM) contribute to language function in Down syndrome (DS). We proposed models in which relations of SA to language in DS are mediated by STM. Thirty-seven youth with DS aged 10-22 years (M = 15.59) completed SA, STM, and language tasks. Cross-sectional mediation analyses were run with the bootstrapping method. We found significant indirect effects of SA separately on vocabulary and syntax through auditory STM with point estimates of -.30 and -.31, respectively. Results suggest lapses in SA compromise auditory STM, which in turn impacts vocabulary and syntax in youth with DS; however, further research is needed to confirm causality. Addressing SA and STM in language therapy with youth with DS could lead to improved outcomes.

Charting the trajectory of forgetting: Insights from a working memory period paradigm

Working memory capacity is commonly measured in terms of its item span, and much less often in terms of its time span, or “period.” The former measures how many items can be stored in working memory when carrying out episodes of concurrent processing. The latter complements this by determining the duration of processing episodes that can be tolerated while successfully storing a fixed number of items. We investigated the generality of previous evidence that working memory period varies with the distribution of longer and shorter processing episodes within a trial, and that notwithstanding such differences, a global measure of period is a reliable predictor of children’s educational attainment. We describe data from 184 children, between 7 and 11 years of age, who completed variants of an operation period task with different distributions of processing episodes together with measures of scholastic attainment. Individual differences in period scores were consistent over two test sessions, and were predictive of reading and number skills. We replicated previous effects of the order of longer and shorter processing episodes, but found that they did not generalize fully to other manipulations of order. The results point to the contribution of subtle within-trial sequence configurations for working memory. We make the case for a broader view of what constrains working memory than exists in current models.

Does articulatory rehearsal help immediate serial recall?

Articulatory rehearsal is assumed to benefit verbal working memory. Yet, there is no experimental evidence supporting a causal link between rehearsal and serial-order memory, which is one of the hallmarks of working memory functioning. Across four experiments, we tested the hypothesis that rehearsal improves working memory by asking participants to rehearse overtly and by instructing different rehearsal schedules. In Experiments 1a, 1b, and 2, we compared an instructed cumulative-rehearsal condition against a free-rehearsal condition. The instruction increased the prevalence of cumulative rehearsal, but recall performance remained unchanged or decreased compared to the free-rehearsal baseline. Experiment 2 also tested the impact of a fixed rehearsal instruction; this condition yielded substantial performance costs compared to the baseline. Experiment 3 tested whether rehearsals (according to an experimenter-controlled protocol) are beneficial compared to a matched articulatory suppression condition that blocked rehearsals of the memoranda. Again, rehearsing the memoranda yielded no benefit compared to articulatory suppression. In sum, our results are incompatible with the notion that rehearsal is beneficial to working memory.

Short-Term Storage and Executive Working Memory Processing Predict Fluid Intelligence in Primary School Children

Working memory (WM) includes short-term storage and executive processing of information. WM has been suggested to be one of the key concepts to explain individual differences in fluid intelligence (Gf). However, only a few studies have investigated the association of the two different aspects of WM in relation to Gf. Furthermore, even fewer studies have included children. Therefore, we first investigated the inter-relations between the WM aspects (verbal and visual-spatial storage, verbal and visual-spatial executive processing). Second, we explored the relation between a general WM factor and Gf. Third, we analyzed the relations between the different WM aspects and Gf while we controlled for common variance among all WM tasks. Nine- to 11-year olds had to solve simple and complex span tasks. Correlations and structural equation modeling techniques were used to examine these relations. Most inter-relations among simple and complex spans were found to be substantial and positive. The general WM factor was related to Gf. Furthermore, after controlling for common variance among all WM tasks, individual differences in verbal storage, visual-spatial storage and verbal processing still uniquely related to Gf. Visual-spatial processing, however, was not related to Gf. Results are discussed in terms of underlying mechanisms.