Individual and age-related differences in children’s working memory

The purpose of this study was to investigate the degree to which age-related and individual differences in children’s working memory (WM) are due to a general or task-specific capacity system. Experiment 1 correlated children’s (N=146; age range 5–19 years) verbal and visual-spatial working memory performance with various intelligence and achievement measures. The results supporting a general system were that (1) visual-spatial and verbal WM measures were significantly intercorrelated with and without age partialed out and (2) both verbal and visual-spatial WM measures were significantly correlated with diverse achievement and intelligence measures. Experiment 2 compared three age groups (N=192; 7-, 10-, and 13-year-olds) on working-memory performance tasks under initial, enhanced (cued), and maintenance conditions. The results supporting a general capacity system were that (1) age-related performance differences in WM were found on all conditions and not isolated to specific processes, (2) the maintenance measures (high-load condition) predicted the variance better in age-related performance than process measures, and (3) although individual differences in WM performance reflected two independent operations, these operations produced similar correlations to achievement within age groups. Overall, the results support a general capacity explanation of age-related and individual differences in children’s WM performance.     

“That man’s father is my father’s son”: The roles of structure,strategy, and working memory in solving convoluted verbal problems

Normative data (N=896) collected on solutions to the traditional reasoning problem “Brothers and sisters have I none,/That man’s father is my father’s son” was the platform for a set of experiments to investigate the roles of problem structure, subject strategy, and working memory in error making in a class of verbal problems. The normative data revealed that the modal, but incorrect response to the brothers and sisters problem was “himself,” whereas the correct response of “son” was given by only 17% of subjects for the traditional version above, rising to 40% for a reordered novel version. This problem’s structure, identified as adouble-modifier structure, was found to produce similar response patterns across a range of verbal problems. Results from (1) syntactical structure manipulations (e.g., “My father’s son is the father of that man”), and (2) efforts to teach subjects to use a linear strategy (a sequence of steps), interpreted within a framework of Just and Carpenter’s (1992) capacity theory of comprehension, suggested that working memory overload varies across within-structure modifications and subjects. Further-more, this overload may be compounded by subjects’ choices of strategy.     

The role of redundant verbal labels in 8- and 10-month-olds’ working memory

Verbal labels have been shown to help preverbal infants’ performance on various cognitive tasks, such as categorization. Redundant labels also aid adults’ visual working memory (WM), but it is not known if this linguistic benefit extends to preverbal infants’ WM. In two eye-tracking studies, we tested whether 8- and 10-month-old infants’ WM performance would improve with the presence of redundant labels in a Delayed Match Retrieval (DMR) paradigm that tested infants’ WM for object-location bindings. Findings demonstrated that infants at both ages were unable to remember two object-location bindings when co-presented with labels at encoding. Moreover, infants who encoded the object-location bindings with labels were not significantly better than those who did so in silence. These findings are discussed in the context of label advantages in cognition and auditory dominance.     

Being a good witness: The roles of benevolence and working memory capacity in rapport’s effect on eyewitness memory

Prior studies suggest that building rapport with eyewitnesses can produce measurable recall improvements, but the underlying mechanisms of rapport’s possible effects on recall remain underexplored. The present study investigated two possible mechanisms for rapport’s impact: (1) improved working memory capacity and (2) increased benevolence. Participants (N = 105) viewed a mock theft video, followed by one of two possible pre-interview interactions: rapport-building or a control interaction. Next, participants completed measures of working memory, altruism, and benevolence (pre-interview and post-interview), before recalling details of the theft. Analyses revealed that, when controlling for the effects of the interaction duration and participants’ pre- and post-interview benevolence, rapport did not affect eyewitness recall directly. However, rapport building did increase benevolence measured after and associated with the substantive eyewitness interview, which in turn predicted more accurate and new details reported, and fewer subjective/other details reported. These findings support benevolence toward the interviewer as a mechanism behind rapport’s effect on eyewitness recall. Implications for investigative interviews in relation to benevolence and motivating reciprocation are discussed.     

The roles of different executive functioning skills in young children’s mental computation and applied mathematical problem-solving

This study investigated the relationships of four executive functioning skills (including verbal working memory, spatial working memory, inhibitory control, and cognitive flexibility) with young children’s mental computation and applied mathematical problem-solving. Two hundred and twenty-five Chinese kindergarteners were tested with a battery of general cognitive, executive functioning and mathematics skills. Results showed that when children’s age, gender, non-verbal intelligence, and listening comprehension skills were controlled, verbal working memory and cognitive flexibility were significant correlates of mental computation, whereas verbal working memory, spatial working memory, and cognitive flexibility were significant correlates of applied mathematical problem-solving. Inhibitory control was not significantly associated with the two domains of mathematics under investigation. The findings highlight the differential roles of different executive functioning skills in early mathematical skills and offer practical implication for helping young children in learning complex mathematical skills.     

How are visuospatial working memory, executive functioning, and spatial abilities related? A latent-variable analysis.

This study examined the relationships among visuospatial working memory (WM) executive functioning, and spatial abilities. One hundred sixty-seven participants performed visuospatial short-term memory (STM) and WM span tasks, executive functioning tasks, and a set of paper-and-pencil tests of spatial abilities that load on 3 correlated but distinguishable factors (Spatial Visualization, Spatial Relations, and Perceptual Speed). Confirmatory factor analysis results indicated that, in the visuospatial domain, processing-and-storage WM tasks and storage-oriented STM tasks equally implicate executive functioning and are not clearly distinguishable. These results provide a contrast with existing evidence from the verbal domain and support the proposal that the visuospatial sketchpad may be closely tied to the central executive. Further, structural equation modeling results supported the prediction that, whereas they all implicate some degree of visuospatial storage, the 3 spatial ability factors differ in the degree of executive involvement (highest for Spatial Visualization and lowest for Perceptual Speed). Such results highlight the usefulness of a WM perspective in characterizing the nature of cognitive abilities and, more generally, human intelligence.     

Evidence for spontaneous serial refreshing in verbal working memory?

Working memory (WM) keeps information temporarily accessible for ongoing cognition. One proposed mechanism to keep information active in WM is refreshing. This mechanism is assumed to operate by bringing memory items into the focus of attention, thereby serially refreshing the content of WM. We report two experiments in which we examine evidence for the spontaneous occurrence of serial refreshing in verbal WM. Participants had to remember series of red letters, while black probe letters were presented between these memory items, with each probe to be judged present in or absent from the list presented so far, as quickly as possible (i.e., the probe–span task). Response times to the probes were used to infer the status of the representations in WM and, in particular, to examine whether the content of the focus of attention changed over time, as would be expected if serial refreshing occurs spontaneously during inter-item pauses. In sharp contrast with this hypothesis, our results indicate that the last-presented memory item remained in the focus of attention during the inter-item pauses of the probe–span task. We discuss how these findings help to define the boundary conditions of spontaneous refreshing of verbal material in WM, and discuss implications for verbal WM maintenance and forgetting.     

Individual differences in speakers’ perspective taking: The roles of executive control and working memory

Both speaking and listening require taking into account the perspective of one’s communicative partner. Is perspective taking a domain-specific process internal to the language production and comprehension systems? Or is it a domain-general process regulated by the same mechanisms that are used to regulate other forms of behavior? Past research has shown that listeners’ perspective taking is at least partially regulated by inhibitory control and working memory (WM), suggesting that it may be best thought of in domain-general terms. The present experiment was designed to explore individual differences in nonlinguistic executive functioning in order to assess whether domain-general mechanisms help regulate speakers’ perspective-taking behavior. A group of 60 speakers participated in a referential communication task and in tasks measuring WM and executive control (EC). The results revealed that WM and EC were both predictive of the speakers’ perspective taking, suggesting that perspective taking may be regulated by domain-general mechanisms.     

Working memory and phonological processing as predictors of children’s mathematical problem solving at different ages

The study explored the contribution of working memory (WM) to mathematical problem solving in younger (8-year-old) and older (11-year-old) children. The results showed that (1) significant age-related differences in WM performance were maintained when measures of phonological processing (i.e., digit naming speed, short-term memory, phonological deletion) were partialed from the analysis; (2) WM predicted solution accuracy of word problems independently of measures of problem representation, knowledge of operations and algorithms, phonological processing, fluid intelligence, reading, and math skill; and (3) a second-order WM factor was correlated with problem solving, suggesting that a general or executive system underlies age-related performance. The results were interpreted as support for the notion that the executive system was an important predictor of age-related changes in problem solving beyond the contribution of math and reading skills, and this system operates independently of the phonological system and domain-specific knowledge in predicting solution accuracy.     

Age differences in working memory— The roles of storage and selective access

Twenty-four young (23 years) and 24 old (71 years) adults performed arithmetic tasks with working memory loads ranging from 1 to 4. Age groups were equivalent in mean accuracy and speed of arithmetic operations under minimal working memory load, but old adults were slower than young with memory demands >1. Access to a new object in working memory as the basis of computation required additional time. This object-switching cost increased with increases in memory demand, but was unaffected by age, indicating that old adults have no deficit in selective access to working memory.     

Selective storage and maintenance of an object’s features in visual working memory

It has been shown that we have a highly capacity-limited representational space with which to store objects in visual working memory. However, most objects are composed of multiple feature attributes, and it is unknown whether observers can voluntarily store a single attribute of an object without necessarily storing all of its remaining features. In this study, we used a masking paradigm to measure the efficiency of encoding, and neurophysiological recordings to directly measure visual working memory maintenance while subjects viewed multifeature objects and were required to remember only a single feature or all of the features of the objects. We found that measures of both encoding and maintenance varied systematically as a function of which object features were task relevant. These experiments show that individuals can control which features of an object are selectively stored in working memory.     

Does relocating information in text depend on verbal or visuospatial abilities? An individual-differences analysis

In this individual-differences study, we evaluated the prevalent view that relocating information in a previously read text depends primarily on visuospatial abilities. Participants read a text, answered fillin-the-blank test questions, and identified which page and line in the original text contained the sentence in each question. They also completed a battery of verbal and visuospatial tasks. Performance on verbal tasks was highly predictive of the accuracy of both page and line identifications, and this correlation remained significant even after we controlled for performance on visuospatial tasks. In contrast, performance on visuospatial tasks was not predictive of either page or line identification accuracy, once verbal abilities were controlled for. These results suggest an important role for verbal abilities in relocation of text information and a lesser role for visuospatial abilities than has previously been assumed.     

Is verbal–spatial binding in working memory impaired by a concurrent memory load?

Binding processes play a critical role in memory. We investigated whether the binding of (visually presented) verbal and spatial (locations) information involves general attentional resources, as stipulated in the revised working memory model, by comparing measures of binding in the presence and absence of a concurrent memory load. Using an adaptation of a probe recognition task contrasting performance between intact and recombined conditions, we found that the concurrent retention of a sequence of three pure tones eliminated verbal–spatial binding. The present study constitutes the first to directly measure the impact of a concurrent memory load on verbal–spatial binding and suggests that such binding may indeed recruit attentional resources, consistent with some recent findings in the visual–spatial binding literature.     

The importance of working memory updating in the Prisoner’s dilemma

Successful cooperation requires that humans can flexibly adjust choices to their partner’s behaviour. This, in turn, presupposes a representation of a partner’s past decisions in working memory. The aim of the current study was to investigate the role of working memory processes in cooperation. For that purpose, we tested the effects of working memory updating (Experiment 1) and working memory maintenance demands (Experiments 2 and 3) on cooperative behaviour in the Prisoner’s dilemma game. We found that demands on updating, but not maintenance, of working memory contents impaired strategy use in the Prisoner’s dilemma. Thus, our data show that updating a partner’s past behaviour in working memory represents an important precondition for strategy use in cooperation.     

Children’s higher order cognitive abilities and the development of secondary memory

The relations between higher cognitive abilities and immediate and delayed recall were studied in 57 children (6–16 years of age). The participants were tested repeatedly on free recall of a supraspan list (Children’s Memory Scale), and their fluid ability was also assessed (Woodcock—Johnson III Spatial Relations). Consistent with Unsworth and Engle’s (2007) account of the relation between memory and higher order cognition, the children’s fluid ability was significantly correlated with retrieval from secondary memory, regardless of whether it was measured using immediate or delayed recall. Multiple regression analyses provided further support for this view, revealing that measures of immediate and delayed retrieval from secondary memory accounted for the same variance in the children’s fluid ability.     

Are there gender differences in verbal and visuospatial working-memory resources?

Whereas women generally outperform men in episodic-memory tasks, little is known as to how the genders compare with respect to basic working-memory operations. In reference to Baddeley's (1986) model, the present study searched for possible gender differences in terms of accuracy (but not speed) of working-memory processes. Men and women completed series of working-memory tasks respectively involving verbal and visuospatial information, as well as a double-span task involving both classes of information. Control measures included verbal fluency and mental rotation tasks in which gender differences are frequently obtained. In these tasks, the results showed several of the expected gender contrasts. However, men and women were not found to differ significantly in any type of working memory save in the double-span task where women surpassed men. The patterns of task intercorrelation were largely similar in both genders. Discussion emphasises the manifestation, based on the present exploration, of an almost identical working-memory architecture in men and women.     

Integrated cross-domain object storage in working memory: Evidence from a verbal–spatial memory task

Working-memory theories often include domain-specific verbal and visual stores (e.g., the phonological and visuospatial buffers of Baddeley, 1986), and some also posit more general stores thought to be capable of holding verbal or visuospatial materials (Baddeley, 2000; Cowan, 2005). However, it is currently unclear which type of store is primarily responsible for maintaining objects that include components from multiple domains. In these studies, a spatial array of letters was followed by a single probe identical to an item in the array or differing systematically in spatial location, letter identity, or their combination. Concurrent verbal rehearsal suppression impaired memory in each of these trial types in a task that required participants to remember verbal–spatial binding, but did not impair memory for spatial locations if the task did not require verbal–spatial binding for a correct response. Thus, spatial information might be stored differently when it must be bound to verbal information. This suggests that a cross-domain store such as the episodic buffer of Baddeley (2000) or the focus of attention of Cowan (2001) might be used for integrated object storage, rather than the maintenance of associations between features stored in separate domain-specific buffers.     

The role of verbal memory in regressions during reading is modulated by the target word’s recency in memory

During reading, a number of eye movements are made backward, on words that have already been read. Recent evidence suggests that such eye movements, called regressions, are guided by memory. Several studies point to the role of spatial memory, but evidence for the role of verbal memory is more limited. In the present study, we examined the factors that modulate the role of verbal memory in regressions. Participants were required to make regressions on target words located in sentences displayed on one or two lines. Verbal interference was shown to affect regressions, but only when participants executed a regression on a word located in the first part of the sentence, irrespective of the number of lines on which the sentence was displayed. Experiments 2 and 3 showed that the effect of verbal interference on words located in the first part of the sentence disappeared when participants initiated the regression from the middle of the sentence. Our results suggest that verbal memory is recruited to guide regressions, but only for words read a longer time ago.     

Infants’ behaviours elicit different verbal,nonverbal, and multimodal responses from caregivers during early play

Caregivers use a range of verbal and nonverbal behaviours when responding to their infants. Previous studies have typically focused on the role of the caregiver in providing verbal responses, while communication is inherently multimodal (involving audio and visual information) and bidirectional (exchange of information between infant and caregiver). In this paper, we present a comprehensive study of caregivers’ verbal, nonverbal, and multimodal responses to 10-month-old infants’ vocalisations and gestures during free play. A new coding scheme was used to annotate 2036 infant vocalisations and gestures of which 87.1 % received a caregiver response. Most caregiver responses were verbal, but 39.7 % of all responses were multimodal. We also examined whether different infant behaviours elicited different responses from caregivers. Infant bimodal (i.e., vocal-gestural combination) behaviours elicited high rates of verbal responses and high rates of multimodal responses, while infant gestures elicited high rates of nonverbal responses. We also found that the types of verbal and nonverbal responses differed as a function of infant behaviour. The results indicate that infants influence the rates and types of responses they receive from caregivers. When examining caregiver-child interactions, analysing caregivers’ verbal responses alone undermines the multimodal richness and bidirectionality of early communication.