Does the extension of free time trigger spontaneous elaborative strategies in working memory?

Elaboration has emerged as a potential maintenance mechanism involved in the substantial contribution of long-term memory (LTM) to working memory (WM) performance. The objective of the current study was to determine whether elaborative strategies could be spontaneously implemented under favorable conditions. Across four experiments, the distribution of free-time periods was manipulated in a complex span task, while keeping the total amount of free time and cognitive load constant. As elaboration requires time to be set up, Experiment 1 elicited better WM performance in a condition with fewer long free-time periods compared to a condition with many short free-time periods. However, because this benefit did not persist during delayed recall, the following experiments aimed to further investigate this effect by manipulating factors supposed to modulate elaboration. In Experiment 2, half of the participants received no specific instructions regarding strategies whereas the other half were encouraged to use elaborative strategies. In Experiment 3, the to-be-maintained stimuli did or did not have LTM representations that are essential for elaboration (i.e., words or pseudowords). Finally, the last experiment used a self-strategy report to better understand the nature of the WM maintenance strategies spontaneously employed by participants. Despite a consistent effect of free time manipulation on WM recall, the explanatory assumption of elaboration was challenged by the unexpected lack of effect on LTM recall and on the type of strategy reported. Alternative explanations stemming from well-known factors influencing WM performance are discussed, and emphasis is placed on the potential contribution of direct semantic maintenance in WM.

Performance on the processing portion of complex working memory span tasks is related to working memory capacity estimates.

Individual differences in working memory capacity (WMC) have long been known to relate to performance in domains outside of WM, including attentional control, long-term memory, problem-solving, and fluid intelligence to name a few. Complex span WM tasks, composed of a processing component and a storage component, are often used to index WMC in these types of investigations. Capacity estimates are derived from performance on the storage component only, while processing performance is often largely ignored. Here, we explore the relationship between processing performance and WMC in a large dataset for each of three complex span tasks to better characterize how the components of these tasks might be related. We provide evidence that enforcing an 85% or better accuracy criterion for the processing portion of the task results in the removal of a disproportionate number of individuals exhibiting lower WMC estimates. We also find broad support for differences in processing task performance, characterized according to both accuracy and reaction time metrics, as a function of WMC. We suggest that researchers may want to include processing task performance measures, in addition to capacity estimates, in studies using complex span tasks to index WMC. This approach may better characterize the relationships between complex span task performance and performance in disparate domains of cognition.

Measuring working memory capacity in children using adaptive tasks: Example validation of an adaptive complex span.

Working memory tasks designed for children usually present trials in order of ascending difficulty, with testing discontinued when the child fails a particular level. Unfortunately, this procedure comes with a number of issues, such as decreased engagement from high-ability children, vulnerability of the scores to temporary mind-wandering, and large between-subjects variations in number of trials, testing time, and proactive interference. To circumvent these problems, the goal of the present study was to demonstrate the feasibility of assessing working memory using an adaptive testing procedure. The principle of adaptive testing is to dynamically adjust the level of difficulty as the task progresses to match the participant's ability. We used this method to develop an adaptive complex span task (the ACCES) comprising verbal and visuo-spatial subtests. The task presents a fixed number of trials to all participants, allows for partial credit scoring, and can be used with children regardless of ability level. The ACCES demonstrated satisfying psychometric properties in a sample of 268 children aged 8-13 years, confirming the feasibility of using adaptive tasks to measure working memory capacity in children. A free-to-use implementation of the ACCES is provided.

How a high working memory capacity can increase proactive interference.

Previous findings suggested that a high working memory capacity (WMC) is potentially associated with a higher susceptibility to proactive interference (PI) if the latter is measured under high cognitive load. To explain such a finding, we propose to consider susceptibility to PI as a net effect of individual executive processes and the intrinsic potential for PI. With the latter, we refer to the amount of information that is activated at a given time and that has the potential to exert PI subsequently. In two studies deploying generalized linear mixed models, susceptibility to PI was modeled as the decline of performance over trials of a complex span task. The results revealed that a higher WMC was associated with a higher susceptibility to PI. Moreover, the number of stimuli recalled in one trial as a proxy variable for the intrinsic potential for PI negatively affected memory performance in the subsequent trial.

The composite complex span: French validation of a short working memory task.

Most studies in individual differences in the field of working memory research use complex span tasks to measure working memory capacity. Various complex span tasks based on different materials have been developed, and these tasks have proven both reliable and valid; several complex span tasks are often combined to provide a domain-general estimate of working memory capacity with even better psychometric properties. The present work sought to address two issues. Firstly, having participants perform several full-length complex span tasks in succession makes for a long and tedious procedure. Secondly, few complex span tasks have been translated and validated in French. We constructed a French working memory task labeled the Composite Complex Span (CCS). The CCS includes shortened versions of three classic complex span tasks: the reading span, symmetry span, and operation span. We assessed the psychometric properties of the CCS, including test-retest reliability and convergent validity, with Raven's Advanced Progressive Matrices and with an alpha span task; the CCS demonstrated satisfying qualities in a sample of 1,093 participants. This work provides evidence that shorter versions of classic complex span tasks can yield valid working memory estimates. The materials and normative data for the CCS are also included.

Evaluation of children's cognitive load in processing and storage of their spatial working memory.

Working memory performance affects children's learning. This study examined objective (task performance), subjective (self-report), and physiological (pupil dilation) cognitive load (CL) while children completed a spatial working memory complex span task. Frist, 80 Taiwanese 11-year-olds (40 boys) who participated in Experiment 1 confirmed the suitability of the materials. Then, 72 Taiwanese 11-year-olds (35 boys) were assigned to high and low complexity groups to participate in Experiment 2 to test the study hypothesis. Children had to recall at the end of a dual-task list and answer two questions regarding the difficulty and mental effort involved in processing and storage. Their pupil diameters were recorded using an eye-tracker. Two-way mixed ANOVA found that the processing requirements and memory load reduced storage and aggravated the subjective CL of storage; the subjective CL of processing was higher under highly complex conditions. Stepwise regression analysis indicated that subjective CL of processing predicted memory performance in low CL conditions, and physiological CL of processing predicted it in high CL conditions.

Working memory complex span tasks and fluid intelligence: Does the positional structure of the task matter?

The complex span task used to evaluate working memory (WM) capacity has been considered to be the most predictive task of fluid intelligence. However, the structure of the complex span tasks varies from one study to another, and it has not been questioned yet whether these variants could influence the predictive power of these tasks. Previous studies have typically used either structures based on alternating processing-storage patterns or alternating storage-processing patterns. We present one experiment in which the participants were submitted to both the processing-storage vs. storage-processing types. After completing both types of complex span tasks, the participants performed a reasoning test (Matrix Reasoning of the Wechsler Adult Intelligence Scale - WAIS-IV). The results showed a significant difference in the WM spans between the two conditions, with higher spans observed in the processing-storage alternating structure, and different serial position curves. However, the correlations showed that both types of tasks remained equally predictive of performance in the reasoning test. These results are discussed in regard to the time-based resource-sharing model.

The association of eye movements and performance accuracy in a novel sight-reading task.

The present study investigated how eye movements were associated with performance accuracy during sight-reading. Participants performed a complex span task in which sequences of single quarter note symbols that either enabled chunking or did not enable chunking were presented for subsequent serial recall. In between the presentation of each note, participants sight-read a notated melody on an electric piano in the tempo of 70 bpm. All melodies were unique but contained four types of note pairs: eighth-eighth, eighthquarter, quarter-eighth, quarter-quarter. Analyses revealed that reading with fewer fixations was associated with a more accurate note onset. Fewer fixations might be advantageous for sight-reading as fewer saccades have to be planned and less information has to be integrated. Moreover, the quarter-quarter note pair was read with a larger number of fixations and the eighth-quarter note pair was read with a longer gaze duration. This suggests that when rhythm is processed, additional beats might trigger re-fixations and unconventional rhythmical patterns might trigger longer gazes. Neither recall accuracy nor chunking processes were found to explain additional variance in the eye movement data.

Aging Influences the Efficiency of Attentional Maintenance in Verbal Working Memory.

OBJECTIVES: Numerous studies reported an age-related deficit in verbal working memory (WM). Beyond the well-established general factors of cognitive aging, the alteration of the specific WM maintenance mechanisms may account for this deficit. This paper aims to investigate the hypothesis that WM attentional maintenance is impaired with age. METHOD: In a WM task adapted to individual short-term memory and processing speed, younger and older participants maintained letters while verbally responding to a concurrent processing task, in order to constrain the use of rehearsal. Critically, the opportunity to use attentional maintenance was manipulated by varying the cognitive load (CL) of the concurrent processing via its nature and pace. RESULTS: Younger participants outperformed older participants and, in both groups, recall performance decreased as the CL increased. Importantly, in line with our predictions, the CL effect was modulated by age. Older adults benefited less from free pauses that allowed participants to engage in attentional maintenance of WM traces. DISCUSSION: Although still effective in normal aging, WM attentional maintenance seems to be altered. It could therefore be a good candidate to account for WM age-related deficits.

Revealing the Electrophysiological Correlates of Working Memory-Load Effects in Symmetry Span Task With HHT Method.

Complex span task is one of the commonly used cognitive tasks to evaluate an individual's working memory capacity (WMC). It is a dual task consisting of a distractor subtask and a memory subtask. Though multiple studies have utilized complex span tasks, the electrophysiological correlates underlying the encoding and retrieval processes in working memory span task remain uninvestigated. One previous study that assessed electroencephalographic (EEG) measures utilizing complex span task found no significant difference between its working memory loads, a typical index observed in other working memory tasks (e.g., n-back task and digital span task). The following design constructs of the paradigm might have been the reason. (1) The fixed-time limit of the distractor subtask may have hindered the assessment of individual WMC precisely. (2) Employing a linear-system-favoring EEG data analysis method for a non-linear system such as the human brain. In the current study, the participants perform the Raven Advanced Progressive Matrices (RAMP) task on 1 day and the symmetry span (Sspan) task on the other. Prior to the formal Sspan task, the participants were instructed to judge 15 simple symmetry questions as quickly as possible. A participant-specific time-limit is chartered from these symmetry questions. The current study utilizes the Sspan task sequential to a distractor subtask. Instead of the fixed time-limit exercised in the previous study, the distractor subtask of the current study was equipped with the participant-specific time-limit obtained from the symmetry questions. This could provide a precise measure of individual WMC. This study investigates if the complex span task resonates EEG patterns similar to the other working memory tasks in terms of working memory-load by utilizing ensemble empirical mode decomposition (EEMD) of Hilbert-Huang transform (HHT). Prior expectations were to observe a decrement in the P300 component of event-related mode (ERM) and a decrement in the power of alpha and beta band frequency with increasing working memory-load. We observed a significantly higher P300 amplitude for the low-load condition compared to the high-load condition over the circumscribed brain network across F4 and C4 electrodes. Time-frequency analysis revealed a significant difference between the high- and low-load conditions at alpha and beta band over the frontal, central, and parietal channels. The results from our study demonstrate precise differences in EEG data pertaining to varied memory-load differences in the complex span task. Thus, assessing complex span tasks with the HHT-based analysis may aid in achieving a better signal to noise ratio and effect size for the results in working memory EEG studies.

What makes working memory traces stable over time?

Understanding the factors that make working memory (WM) traces stable over time is important because WM is the keystone of general cognitive achievement. Two views of attentional WM maintenance have been suggested to account for the long-term retention of WM information. First, the distractors in a WM task are thought to foster the creation of episodic memory cues through covert retrieval. Second, the cognitive load (CL) of the distractors is thought to vary long-term memory instantiation. In this study, we propose an additional parsimonious perspective: the total time during which each trace is under the control of attention in WM is the key to long-term retention. Participants performed a complex span task in which the CL and number of distractors were orthogonally manipulated, and thereafter the participants performed a delayed recall test. Similar to previous findings, the results showed effects of the number of distractors and of CL on delayed recall. Our results went further, however, by showing a non-linear relationship between delayed recall performance and the free time accumulated between encoding and immediate recall. The role of time in episodic memory performance and the underlying WM maintenance mechanism are discussed.