Sergio Morra

This editorial presents a special collection on working memory and executive functions. Six articles are presented and their contributions to current theoretical debates are briefly discussed.

This article investigates children’s graphic representation of two complex motor skills, snowboarding and aikido, from the perspective of drawing flexibility research. In particular, the role of working memory capacity in the development of drawing flexibility is examined. A total of 127 children in the age range 5.7–11.9 years were shown short videos of snowboarding and aikido and were required to make drawings of them. In addition, participants were administered Goodenough’s Draw-a-man Test (that measures the ability to draw detail and proportion in the human figure) and two working memory tests (the Mr. Cucumber test and the Backward Digit Span). The snowboarding and aikido drawings were scored for 19 or 13 features, respectively, on which they could differ from the participant’s standard drawing of a person. The snowboarding and aikido scores were correlated, also controlling for age and Draw-a-man scores, indicating a common variance for drawing flexibility. The drawing flexibility scores increased with age, and were correlated with working memory capacity, also controlling for age and Draw-a-man scores. These results are consistent with a neo-Piagetian model of drawing flexibility development. Detailed analyses are also provided on children’s production of stick figures and “transparencies,” and on the relation of each single modified feature with age and working memory capacity.

Limited attentional capacity is essential to working memory. How its limit should be assessed is a debated issue. Five experiments compare Cowan’s 4-units and Pascual-Leone’s 7-units models of limited working memory capacity, with presentation time and attention to operative schemes as potential explanations of this discrepancy. Experiments 1a–1c used the Compound Stimuli Visual Information (CSVI) task, with long versus brief presentation. Capacity was estimated with the Bose-Einstein model, assuming a different number of attending acts in each condition. Participants’ k estimates in both conditions were highly correlated and the means were not different, indicating that the same capacity is assessed in both conditions. Experiments 2 and 3 used the 5000-msec CSVI, and the Visual Array Task (VAT) in two conditions (5000- vs. 120-msec presentation). Capacity in the VAT was estimated with Morey’s Bayesian method. Participants’ k estimates in both VAT conditions were correlated, but the mean was higher with long presentation, suggesting that the long condition benefits from recoding or chunking. The k estimate in the CSVI correlated with the short VAT and (to a lesser degree in Exp.2) with the long VAT. The mean estimate of k in the CSVI was one unit more than in the short VAT. We conclude that the CSVI and the short VAT tap the same capacity, one unit of which in the short VAT is allocated to an operative scheme; we discuss how Cowan’s and Pascual-Leone’s views on limited capacity can be reconciled.

This study aims at investigating the relationship between working memory updating and working memory capacity in preschool children. A sample of 176 preschoolers (36–74 months) was administered a working memory updating task (Magic House) along with three working memory capacity tests that specifically measure their core attentional component (M capacity, as defined in the theory of constructive operators): Backward Word Span, Mr. Cucumber, and Direction Following Task. Correlational analyses and cross-classification prediction analyses were performed. Updating and capacity were significantly correlated, although the correlations were not high when age was partialled out. Capacity increased with age, and mediated the relation between age and updating. More importantly, cross-classification prediction analysis revealed that high updating scores with low M capacity, and low updating scores with relatively high M capacity, are possible events; the only combination ruled out was a low updating score with precocious development of M capacity. These facts demonstrate that updating skills in preschoolers depends on M capacity but does not coincide with it. Therefore, in cognitive developmental theories, the constructs of working memory updating and capacity should be distinguished, and on practical grounds, different tests should be used to measure them.

Working memory capacity and executive functions play important roles in the early development of drawing and language, but we lack models that specify the relationships among these representational systems and cognitive functions in toddlers. To respond to this need, the present study investigated the relations between drawing and language in very young children, and the role of working memory capacity, inhibition, and shifting in the association between these two representational systems. The participants were 80 children, 25–37 months old. The results revealed that in toddlers (a) all the measures of working memory, inhibition, and shifting loaded on a single factor of general executive functioning; (b) language and drawing are two distinct, but substantially correlated, representational systems; and (c) the development of executive function has a strong impact on language development, which in turn influences the development of drawing.

Studying the role of individual differences in team sports performance is a challenge. The main problem is having an available measure of individual performance of each member of the team. In particular, in youth sports, where the level of specialization is reactively low, it appears appropriate that this measure takes the entire performance of the athlete into consideration (i.e., that it assesses all of the athlete’s gestures), while maintaining an ecological validity criterion. Therefore, we devised and calculated an individual assessment measure in volleyball following the subsequent steps: Firstly, we video-recorded at least three volleyball games for each of the 114 youth volleyball players who participated in the study. Then, two independent expert observers evaluated each individual performance by attributing a score to every single gesture performed by the athletes during the games. The derived individual score was adjusted and controlled for the team performance measure, namely the result of each Set the athlete participated in (and for the amount of participation of the athlete to each game). The final measure of individual performance in volleyball proved to be reliable, showing a high level of interrater agreement (r = .841, p < .001) and a significant correlation with the amount of experience in volleyball (r = .173, p < .05).

This article reconsiders Case’s theory of central conceptual structures (CCS), examining the relation between working memory and the acquisition of quantitative CCS. The lead hypothesis is that the development of working memory capacity shapes the development of quantitative concepts (whole and rational numbers). Study I, with 779 children from preschool to grade 5, validated a measure of the whole number CCS and found that children’s understanding of whole number advances by one developmental level per additional unit of working memory capacity. Study II, with 92 sixth- and seventh-graders, found that a test of the rational number CCS was predicted by working memory capacity and, to a lesser extent, by intrusion errors in the listening span. We also identified 2 subsets of items that demand a capacity of 4 or 5 units, respectively. Overall, the results support Case’s CCS theory and clarify the role of working memory in the acquisition of numerical concepts. The relevance of these results in relation to the current debate is discussed, with extensive connections to other current theories of whole or rational number comprehension.