Modelling Working Memory Capacity: Is the Magical Number Four, Seven, or Does it Depend on What You Are Counting?

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.

Children's representation of specialized skilled movements: The cases of snowboarding and aikido.

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.

Effect of a quality improvement program on compliance to the sepsis bundle in non-ICU patients: a multicenter prospective before and after cohort study.

Objective: Sepsis and septic shock are major challenges and economic burdens to healthcare, impacting millions of people globally and representing significant causes of mortality. Recently, a large number of quality improvement programs focused on sepsis resuscitation bundles have been instituted worldwide. These educational initiatives have been shown to be associated with improvements in clinical outcomes. We aimed to evaluate the impact of a multi-faceted quality implementing program (QIP) on the compliance of a "simplified 1-h bundle" (Sepsis 6) and hospital mortality of severe sepsis and septic shock patients out of the intensive care unit (ICU). Methods: Emergency departments (EDs) and medical wards (MWs) of 12 academic and non-academic hospitals in the Lombardy region (Northern Italy) were involved in a multi-faceted QIP, which included educational and organizational interventions. Patients with a clinical diagnosis of severe sepsis or septic shock according to the Sepsis-2 criteria were enrolled in two different periods: from May 2011 to November 2011 (before-QIP cohort) and from August 2012 to June 2013 (after-QIP cohort). Measurements and main results: The effect of QIP on bundle compliance and hospital mortality was evaluated in a before-after analysis. We enrolled 467 patients in the before-QIP group and 656 in the after-QIP group. At the time of enrollment, septic shock was diagnosed in 50% of patients, similarly between the two periods. In the after-QIP group, we observed increased compliance to the "simplified rapid (1 h) intervention bundle" (the Sepsis 6 bundle - S6) at three time-points evaluated (1 h, 13.7 to 18.7%, p = 0.018, 3 h, 37.1 to 48.0%, p = 0.013, overall study period, 46.2 to 57.9%, p < 0.001). We then analyzed compliance with S6 and hospital mortality in the before- and after-QIP periods, stratifying the two patients' cohorts by admission characteristics. Adherence to the S6 bundle was increased in patients with severe sepsis in the absence of shock, in patients with serum lactate <4.0 mmol/L, and in patients with hypotension at the time of enrollment, regardless of the type of admission (from EDs or MWs). Subsequently, in an observational analysis, we also investigated the relation between bundle compliance and hospital mortality by logistic regression. In the after-QIP cohort, we observed a lower in-hospital mortality than that observed in the before-QIP cohort. This finding was reported in subgroups where a higher adherence to the S6 bundle in the after-QIP period was found. After adjustment for confounders, the QIP appeared to be independently associated with a significant improvement in hospital mortality. Among the single S6 procedures applied within the first hour of sepsis diagnosis, compliance with blood culture and antibiotic therapy appeared significantly associated with reduced in-hospital mortality. Conclusion: A multi-faceted QIP aimed at promoting an early simplified bundle of care for the management of septic patients out of the ICU was associated with improved compliance with sepsis bundles and lower in-hospital mortality.

Multiple influences of working memory capacity on number comprehension: The interplay with metacognition and number-specific prerequisites.

A wide literature has studied the predictors of number comprehension and early math learning by considering both domain-general and number-specific prerequisites. However, a consensus has not been reached regarding the specific contribution of these prerequisites. This study aimed to analyze the contribution and interplay of two domain-general functions, working memory (WM) and metacognitive abilities, and number-specific prerequisites in determining number comprehension. The participants, 126 Italian first-graders, were tested on two WM capacity tasks, an early metacognition questionnaire, five number-specific prerequisites tasks (e.g., quantity and/or size comparison; placement of Arabic numeral), and the Number Knowledge Test for whole-number comprehension. We hypothesized that WM capacity would predict number comprehension both directly and indirectly via metacognition and domain-specific prerequisites. This is because both metacognition and domain-specific prerequisites might place an information load on WM to establish schemes for declarative metamemory and metacognitive monitoring and for emerging counting skills, respectively. The results confirmed these hypotheses. WM capacity was positively associated with number comprehension both directly and via increased metacognition and domain-specific prerequisites. These findings offer a model for interpreting the interplay between domain-general and number-specific predictors of whole-number comprehension, but they also underline the multiple ways in which WM capacity affects it.

On the Relation between the Development of Working Memory Updating and Working Memory Capacity in Preschoolers.

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.

Executive Function, Language, and the Toddler's Discovery of Representational Drawing.

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.

A working memory span task for toddlers.

This study presents a new working memory measure for toddlers, inspired by the Spin-the-Pots (Hughes & Ensor, 2005), which we modified structuring it as a memory span task. As in the original task, we required toddlers to retrieve objects hidden in little boxes; however, in our Memory Span Spin-the-Pots (MSSP) we used smaller numbers of targets, and we systematically manipulated memory load, covering or not the display, and rotating it or not. Two experiments involved participants between 18 months and three years. In Experiment 1 we examined the effects of covering and rotation on toddlers' memory. Either covering or rotating the stimuli hindered their performance, and combining both transformations yielded an under-additive interaction. Moreover, the effect of covering decreased in the second half of the procedure. In Experiment 2 we validated the MSSP as a working memory measure by comparing it with the Imitation Sorting Task (IST; Alp, 1994). We found that the MSSP correlated with the IST, also with age partialled out, although the IST was easier. In both experiments, the scores increased with age. Overall, this research sheds light on some variables that affect toddlers' performance on the MSSP, and shows that it can be used as a valid working memory measure for toddlers. The results are discussed considering the attentional processes presumably involved.

Assessing Individual Performance in Team Sports: A New Method Developed in Youth Volleyball.

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).

Which tasks measure what? Reflections on executive function development and a commentary on Podjarny, Kamawar, and Andrews (2017).

This article provides a selective review of the literature on executive function development and related topics, focusing on the conceptual and terminological confusions that might hinder communication among researchers in the field. The distinctions between working memory and updating, and between shifting and flexibility, are discussed. Methodological problems, which have implications regarding whether a certain task can be considered a measure of a psychological construct, are also discussed. Research on preschoolers is examined with particular attention because it is a rapidly growing but controversial field that seems in particular need of greater conceptual clarity. As a specific touchstone case, we discuss whether the Multidimensional Card Selection Task (MCST) created by Podjarny, Kamawar, and Andrews (2017) should better be considered a measure of concurrent cognitive flexibility or working memory capacity. It is argued that connecting tasks to theoretical constructs is not warranted unless based on rigorous empirical testing of well-formulated models.

How do we learn to "kill" in volleyball?: The role of working memory capacity and expertise in volleyball motor learning.

This study examines young volleyball players' learning of increasingly complex attack gestures. The main purpose of the study was to examine the predictive role of a cognitive variable, working memory capacity (or "M capacity"), in the acquisition and development of motor skills in a structured sport. Pascual-Leone's theory of constructive operators (TCO) was used as a framework; it defines working memory capacity as the maximum number of schemes that can be simultaneously activated by attentional resources. The role of expertise in motor learning was also considered. The expertise of each athlete was assessed in terms of years of practice and number of training sessions per week. The participants were 120 volleyball players, aged between 6 and 26 years, who performed both working memory tests and practical tests of volleyball involving the execution of the "third touch" by means of technical gestures of varying difficulty. We proposed a task analysis of these different gestures framed within the TCO. The results pointed to a very clear dissociation. On the one hand, M capacity was the best predictor of correct motor performance, and a specific capacity threshold was found for learning each attack gesture. On the other hand, experience was the key for the precision of the athletic gestures. This evidence could underline the existence of two different cognitive mechanisms in motor learning. The first one, relying on attentional resources, is required to learn a gesture. The second one, based on repeated experience, leads to its automatization.

Drawing a dog: The role of working memory and executive function.

Previous research suggests that young children draw animals by adapting their scheme for the human figure. This can be considered an early form of drawing flexibility. This study investigated preschoolers' ability to draw a dog that is different from the human figure. The role of working memory capacity and executive function was examined. The participants were 123 children (36-73 months old) who were required to draw both a person and a dog. The dog figure was scored on a list of features that could render it different from the human figure. Regression analyses showed that both working memory capacity and executive function predicted development in the dog drawing; the dog drawing score correlated with working memory capacity and executive function, even partialling out age, motor coordination, and drawing ability (measured with Goodenough's Draw-a-Man test). These results suggest that both working memory capacity and executive function play an important role in the early development of drawing flexibility. The implications regarding executive functions and working memory are also discussed.

Speeded Probed Recall Is Affected by Grouping.

Most of the evidence from previous studies on speeded probed recall supported primacy-gradient models of serial order representation. Two experiments investigated the effect of grouping on speeded probed recall. Six-word lists, followed by a number between 1 and 6, were presented for speeded recall of the word in the position indicated by the number. Grouping was manipulated through interstimulus intervals. In both experiments, a significant Position × Grouping interaction was found in RT. It is concluded that the results are not consistent with models of order representation only based on a primacy gradient. Possible alternative representations of serial order are also discussed; a case is made for a holistic order representation.

[Acute coronary syndrome and cancer: which therapeutic option first?]. / Sindrome coronarica acuta e neoplasia: quale iter scegliere?

Cardiovascular disease and cancer are the leading causes of mortality worldwide. We report our experience in a cancer patient with acute coronary syndrome successfully treated by hybrid revascularization, i.e. off-pump coronary artery bypass grafting, followed by surgical removal of the tumor and percutaneous coronary intervention. The concomitant presence of cancer and acute coronary syndrome is not rare, ranging from 1.9% to 4.2%. Usually, the most life-threatening disease should be treated first, more frequently coronary artery disease. There are several therapeutic approaches to patients with cancer and coronary artery disease and cancer, including percutaneous coronary intervention, surgical treatment of cancer, or coronary artery bypass grafting. Each of these options should consider the severity of cardiac disease, the stage of malignancy and the clinical conditions of the patient.

How do subvocal rehearsal and general attentional resources contribute to verbal short-term memory span?

Whether rehearsal has a causal role in verbal STM has been controversial in the literature. Recent theories of working memory emphasize a role of attentional resources, but leave unclear how they contribute to verbal STM. Two experiments (with 49 and 102 adult participants, respectively) followed up previous studies with children, aiming to clarify the contributions of attentional capacity and rehearsal to verbal STM. Word length and presentation modality were manipulated. Experiment 1 focused on order errors, Experiment 2 on predicting individual differences in span from attentional capacity and articulation rate. Structural equation modeling showed clearly a major role of attentional capacity as a predictor of verbal STM span; but was inconclusive on whether rehearsal efficiency is an additional cause or a consequence of verbal STM. The effects of word length and modality on STM were replicated; a significant interaction was also found, showing a larger modality effect for long than short words, which replicates a previous finding on children. Item errors occurred more often with long words and correlated negatively with articulation rate. This set of findings seems to point to a role of rehearsal in maintaining item information. The probability of order errors per position increased linearly with list length. A revised version of a neo-Piagetian model was fit to the data of Experiment 2. That model was based on two parameters: attentional capacity (independently measured) and a free parameter representing loss of partly-activated information. The model could partly account for the results, but underestimated STM performance of the participants with smaller attentional capacity. It is concluded that modeling of verbal STM should consider individual and developmental differences in attentional capacity, rehearsal rate, and (perhaps) order representation.

The role of working memory in the development of emotion comprehension.

This study investigated the relationship between emotion comprehension, grammar comprehension, and working memory capacity in children between 5 and 11 years (n= 130), testing the hypothesis that working memory has a role in the development of emotion comprehension. We replicated the correlation between emotion comprehension and grammar comprehension, and found that working memory capacity correlates with both of these variables (also with age statistically controlled). The significant effect of age on emotion comprehension was eliminated when working memory capacity was co-varied. In a regression analysis of emotion comprehension scores, when working memory capacity was entered as a predictor, no additional variance was significantly accounted for by grammar comprehension, gender, or age. A structural relations model, in which the paths from working memory capacity to emotion comprehension and from working memory capacity to grammar comprehension account fully for the correlation between grammar and emotion comprehension, fit the data well. However, working memory capacity was not equally related to all components of the Test of Emotion Comprehension (TEC) (Pons & Harris, 2000), the relationship being significant only for some of them. In particular, working memory capacity has a decisive role in the transition from understanding external to mental aspects of emotions. It is concluded that the development of working memory has a considerable impact on the development of emotion comprehension.

Investigating mental representation of order with a speeded probed recall task.

We compare three models of representation of item order in a verbal STM task: item-item associations, item-position associations, and primacy gradient. A speeded probed recall task is used, in which a list of words is presented, immediately followed by a probe; participants must report as fast as possible the word that was in the probed position. In the number probe condition, a digit is presented and one must say the word in that position. In the word probe condition, the probe is an item of the list and participants must say the immediately following item. Response times (RTs) are analyzed according to probe type and position. The three models imply different predictions about RTs as a function of serial order in the two conditions. Our results suggest a serial, self-terminating search from the beginning of the list to the target position, except for the final position, which is directly accessible. The item-item and item-position association models are ruled out; the primacy gradient model accounts satisfactorily for our results, except for the finding of a larger recency effect with a number probe. Alternative interpretations are also discussed.

Vocabulary learning in primary school children: working memory and long-term memory components.

The goal of this study was to investigate which working memory and long-term memory components predict vocabulary learning. We used a nonword learning paradigm in which 8- to 10-year-olds learned picture-nonword pairs. The nonwords varied in length (two vs. four syllables) and phonology (native sounding vs. including one Russian phoneme). Short, phonologically native nonwords were learned best, whereas learning long nonwords leveled off after a few presentation cycles. Linear structural equation analyses showed an influence of three constructs-phonological sensitivity, vocabulary knowledge, and central attentional resources (M capacity)-on nonword learning, but the extent of their contributions depended on specific characteristics of the nonwords to be learned. Phonological sensitivity predicted learning of all nonword types except short native nonwords, vocabulary predicted learning of only short native nonwords, and M capacity predicted learning of short nonwords but not long nonwords. The discussion considers three learning processes-effortful activation of phonological representations, lexical mediation, and passive associative learning-that use different cognitive resources and could be involved in learning different nonword types.

Traumatic rupture of external carotid artery: report of emergency treatment with Guglielmi detachable coil.

Carotid dissection is a major complication of blunt head and neck trauma. The authors describe a case report of sudden bleeding of a distal branch of the external left carotid artery caused by a fracture of the mandible. This event occurred a week after the trauma. After a first phase consisting in cardiopulmonary resuscitation and blood loss replacement, the placement of a Guglielmi detachable coil (GDC) was considered the best and safest way to stop the bleeding. Guglielmi detachable coil represents a good technique for emergency treatment of bleeding from distal carotid vessels. Given its high cost, the diagnostic study of vessels near mandible fractures should not be considered as routine in cases of head and neck trauma, but should be considered in the presence of local hemorrhage or suspicious neurologic signs.