Impaired performance of children exposed in utero to cocaine on a novel test of visuospatial working memory

The present study examines the potentially harmful effects of prenatal cocaine exposure on later visuospatial memory functions. A novel neuropsychological measure of immediate- and short-term memory for visuospatial information was administered to 40 children, who were identified as cocaine-exposed, and 11 age and socioeconomic status matched controls (all children were 8-9 years old). The Groton Maze Learning Test is a computer-based hidden maze learning test that consists of a 'timed chase test' (a simple measure of visuomotor speed), 5 learning trials on a hidden maze, followed by a delayed recall trial after an 8 min delay. The specific test parameters are chosen based on the age cohort of the subjects. The cocaine-exposed group performed significantly slower on the 'timed chase test,' the last 3 learning trials, and the delayed recall trial (p < or = .05 for all comparisons). Although there was a modest trend for the cocaine-exposed group to make more errors throughout the learning trials, there were no significant group differences. These results suggest that children who were exposed in utero to cocaine exhibit slowed visuomotor speed, a possible impairment in procedural learning, and diminished efficiency in accessing and using the internal spatial map that subjects create to master the maze.     

Visuospatial working memory in Turner's syndrome

Turner's syndrome is a genetic disorder, specific to women, in which one of the X chromosomes is partially or completely deleted. This syndrome is associated with physical features such as short stature or failure in primary and secondary sexual development, together with a specific pattern of cognitive functions. It has been suggested that women affected by Turner's syndrome perform poorly in tasks measuring visuospatial abilities and have a verbal IQ significantly higher than performance IQ. Although this result has received strong empirical support, the nature of the visuospatial deficit is still unclear. Recent studies on visuospatial processes have highlighted that the underlying cognitive structure is more complex than previously suggested and several dissociations have been reported (e.g., visual vs spatial, sequential vs simultaneous, or passive vs active processes). In the present study we analyze in detail the characteristics of the visuospatial deficit associated with Turner's syndrome by presenting four young women with a comprehensive battery of tasks designed to tap all aspects of visuospatial working memory. Results confirm that Turner's syndrome is associated with a general visuospatial working memory deficit, but the pattern of performance of different cases can be different, with a greater emphasis on active visuospatial processes. and on either sequential or simultaneous spatial processes.     

Deviant ERP response to spoken non-words among adolescents exposed to cocaine in utero

Concern for the impact of prenatal cocaine exposure (PCE) on human language development is based on observations of impaired performance on assessments of language skills in these children relative to non-exposed children. We investigated the effects of PCE on speech processing ability using event-related potentials (ERPs) among a sample of adolescents followed prospectively since birth. This study presents findings regarding cortical functioning in 107 prenatally cocaine-exposed (PCE) and 46 non-drug-exposed (NDE) 13-year-old adolescents.PCE and NDE groups differed in processing of auditorily presented non-words at very early sensory/phonemic processing components (N1/P2), in somewhat higher-level phonological processing components (N2), and in late high-level linguistic/memory components (P600).These findings suggest that children with PCE have atypical neural responses to spoken language stimuli during low-level phonological processing and at a later stage of processing of spoken stimuli.     

Visuospatial working memory and mental representation of spatial descriptions

The purpose of the present research is to investigate whether different components of working memory (WM) are involved in processing spatial and nonspatial texts. The interference effects of two concurrent tasks on comprehension and recall of two kinds of text were investigated in two experiments. Each participant listened to a spatial and a nonspatial text, with one of two concurrent tasks: articulatory suppression or spatial tapping. The dependent variables in Experiment 1 were accuracy of recall and verification of information inferred from the texts. In Experiment 2 response times in the verification task were also considered. Results support the hypothesis that verbal and spatial components of working memory are differentially involved in the comprehension and memory of spatial and nonspatial texts, with a selective interference effect of the spatial concurrent task on the spatial text and an interference effect of the verbal concurrent task on both the spatial and nonspatial texts. These effects emerged for recall, sentence verification, and response times. Our findings confirm previous results showing that the verbal component of working memory is involved in the process of text comprehension and memory. In addition, they show that visuospatial working memory is involved, in so far as the text conveys visuospatial information.     

Visuospatial working memory influences the interaction between space and time

How do representations of space inform our perception of time? In language, spatial vocabulary is frequently used to describe temporal concepts, and spatial information biases temporal perception even in non-verbal tasks. In contrast, temporal information typically exerts little, if any, influence on the perception of spatial extent. Here, we used spatial and temporal reproduction tasks, both with and without verbal and spatial dual tasks, to investigate the mechanism underlying the asymmetric relation between space and time. Specifically, we tested whether the asymmetric interference between spatial and temporal stimulus attributes arises from interference in verbal or visuospatial working memory. We found that loading visuospatial working memory, but not verbal working memory, eliminated the asymmetric pattern of interference. This suggests that the interference between spatial and temporal representations arises due to processing constraints in visuospatial working memory. These findings are discussed in terms of the load theory of attention and the relative automaticity with which spatial and temporal information is processed.     

Reactivity and regulation in children prenatally exposed to cocaine

Children prenatally exposed to cocaine may be at elevated risk for adjustment problems in early development because of greater reactivity and reduced regulation during challenging tasks. Few studies have examined whether cocaine-exposed children show such difficulties during the preschool years, a period marked by increased social and cognitive demands and by rapid changes in reactivity and regulation. The authors addressed this question by examining frustration reactivity and regulation of behavior during a problem-solving task in cocaine-exposed and -unexposed preschoolers. Participants were 174 4.5-year-olds (M age = 4.55 years, SD = 0.09). Frustration reactivity was measured as latency to show frustration and number of disruptive behaviors, whereas regulation was measured as latency to approach and attempt the problem-solving task and number of problem-solving behaviors. Results indicated that cocaine-exposed children took longer to attempt the problem-solving task but that cocaine-exposed boys showed the most difficulties: They were quicker to express frustration and were more disruptive. Effect sizes were relatively small, suggesting both resilience and vulnerabilities.     

Visual working memory in young children

Five experiments investigated immediate memory for drawings of familiar objects in children of different ages. The aims were to demonstrate younger children’s greater dependence on visual working memory and to explore the nature of this memory system. Experiment 1 showed that visual similarity of drawings impaired recall in young (5-year-old) children but not in older (10-year-old) children. Experiment 2 showed that younger and older children were affected in contrasting ways when the temporal order of recall was manipulated. Experiment 3 explored a recency effect found in backward recall and investigated its sensitivity to the presentation modality of materials used to produce retroactive interference (RI). For younger children, recency was reduced by visual but not by auditory-verbal RI; for older children, recency was more sensitive to auditoryverbal RI. Experiment 4 confirmed the effect of visual RI on visual recency in young children and showed that the same RI had little effect on their recall of spoken words. These results confirm younger children’s dependence on visual working memory. A final experiment showed that the effects of visual similarity and visual RI are additive, suggesting that they reflect different modes of accessing stored visuospatial information. Implications of these findings for developmental issues and for the nature of visual working memory are discussed.     

Visuospatial bootstrapping: Long-term memory representations are necessary for implicit binding of verbal and visuospatial working memory

It has recently been shown that presenting additional visuospatial information alongside to-be-remembered numbers in a digit span task enhances participants’ memory for those items. However, the mechanisms behind this visuospatial bootstrapping effect have remained unspecified. In this article, we report evidence that this effect involves an integration of information from verbal and visuospatial temporary memory with long-term-memory (LTM) representations and that the existence of a relevant LTM representation is necessary for bootstrapping to occur.     

Response interference and working memory in 12-year-old children.

A group of 69 12-year-old children performed three well-known response interference tasks: the Stroop task, the Eriksen flanker task, and the Simon task. Individual differences in accuracy and speed correlated across the tasks. However, there was no correlation between the interference effects on these three tasks. Stroop interference, but not the Simon or flanker effect, was correlated with working memory capacity, as obtained from the WISC-R. These results may help clarify the nature of ADHD, which is characterized by problems with response interference.     

Visuospatial working memory for locations,colours, and binding in typically developing children and in children with dyslexia and non‐verbal learning disability

This study examined forward and backward recall of locations and colours and the binding of locations and colours, comparing typically developing children – aged between 8 and 10 years – with two different groups of children of the same age with learning disabilities (dyslexia in one group, non‐verbal learning disability [NLD] in the other). Results showed that groups with learning disabilities had different visuospatial working memory problems and that children with NLD had particular difficulties in the backward recall of locations. The differences between the groups disappeared, however, when locations and colours were bound together. It was concluded that specific processes may be involved in children in the binding and backward recall of different types of information, as they are not simply the resultant of combining the single processes needed to recall single features.     

Functional neuroanatomy of spatial working memory in children

Functional magnetic resonance imaging (fMRI) was used to examine spatial working memory in 8- to 11-year-old children tested under three conditions. In the visual condition, children were asked to examine the location of a dot on a screen. In the motor condition, children were instructed to push a button that corresponded to the location of a dot presented on a screen. In the memory condition, children were asked to remember the location of a dot presented 1 or 2 trials previously. Subtracting the activation of the motor condition from the memory condition revealed activity in the dorsal aspects of the prefrontal cortex and in the posterior parietal and anterior cingulate cortex. These findings were also obtained in the analysis of the memory minus visual conditions except that motor cortex activation was also observed. These findings parallel those reported in comparable studies of adults and suggest that fMRI may be a useful means of examining function-structure relations in developmental populations.     

Adaptive training leads to sustained enhancement of poor working memory in children

Working memory plays a crucial role in supporting learning, with poor progress in reading and mathematics characterizing children with low memory skills. This study investigated whether these problems can be overcome by a training program designed to boost working memory. Children with low working memory skills were assessed on measures of working memory, IQ and academic attainment before and after training on either adaptive or non‐adaptive versions of the program. Adaptive training that taxed working memory to its limits was associated with substantial and sustained gains in working memory, with age‐appropriate levels achieved by the majority of children. Mathematical ability also improved significantly 6 months following adaptive training. These findings indicate that common impairments in working memory and associated learning difficulties may be overcome with this behavioral treatment.     

Visual and phonological components of working memory in children

Previous studies have shown that young children's immediate memory for a short series of drawings of objects is mediated by a visual component of working memory, whereas older children rely chiefly upon a phonological component. Three experiments investigated the hypothesis that older children rely also, but to a lesser extent, on visual working memory. Experiment 1 confirmed previous evidence that 11-year-olds' memory is disrupted by phonemic similarity of object names, but is unaffected by visual similarity of the objects themselves. However, when articulatory suppression was used to prevent phonological coding, levels of recall were sensitive to visual rather than phonemic similarity. Experiment 2 compared the effects of interpolating an auditory-verbal or a visual postlist task on memory for drawings viewed either with or without suppression. The visual task had a clear disruptive effect only in the suppression condition, where it interfered selectively with recall of the most recent item. Experiment 3 compared the effects of interpolating an auditory-verbal or a mixed-modality (visual-auditory) postlist task when subjects were not required to suppress. There was greater interference from the mixed-modality task, and this effect was confined to the last item presented. These experiments are taken as confirming the presence of a small but reliable contribution from visual memory in 11-year-old children's recall. As in younger children, visual working memory in 11-year-olds is sensitive to visual similarity and is responsible for a final-item visual recency effect. The results also show that older children's use of visual working memory is usually masked by the more pervasive phonological component of recall. Some implications for the structure of working memory and its development are discussed.     

Visuospatial processing in memory for word location in writing

Two experiments examined how visuospatial processing engaged during text composition intervenes in memory for word location. Experiment 1 showed that in contrast to participants who performed a spatial task concurrently with composing a text, participants who performed a concurrent visual task recalled fewer word locations after the composition. Consequently, it is hypothesized that writers process the written text in order to visually represent its physical layout, and that this representation is then used when locating words. Experiment 2 tested this hypothesis by comparing a standard composition condition (with the written trace) with a condition in which the written trace was suppressed during composition, and with a condition without written trace and with added visual noise. Memory for word location only decreased with visual noise, indicating that construction of the visual representation of the text does not rely on the written trace but involves visual working memory.     

The structure of working memory and how it relates to intelligence in children

This study explored the structure of working memory, and its relationship with intelligence in 176 typically-developing children in the 4th and 5th grades at school. Different measures of working memory (WM), and intelligence (g) were administered. Confirmatory factor analyses showed that WM involves an attentional control system and storage aspects that rely on domain-specific verbal (STM-V) and visuospatial (STM-VS) resources. The structural equation models showed that WM predicts a large portion (66%) of the variance in g, confirming that the two constructs are separable but closely related in young children. Findings also showed that only WM and STM-VS are significantly related to g, while the contribution of STM-V is moderate. Theoretical implications for the relationship between WM and g are discussed.     

The clinical neuropsychology of attention in school-aged children.

100 children from the north-east of England, aged between 7 and 13 years of age, completed an assessment of intellectual ability and an attention battery based on the work of Mirsky, Anthony, Duncan, Ahearn, & Kellam (1991). Factor analysis was generally supportive of the Mirsky et al. (1991) model. Replication of the adult model produced the same four factors: sustain, encode, focus-execute and shift. Replication of the child model produced a three-factor model in which the encode and focus-execute factors combined. An extended model resulted in the introduction of a new factor labelled errors of processing. The scores on attention factors were found to have a reasonable level of independence from intellectual ability.     

When children forget to remember: Effects of reduced working memory availability on prospective memory performance

The preparatory attentional and memory processes theory (PAM) of prospective memory (PM) proposes that prospective remembering is influenced by the variation in the availability of WM resources. Consequently, PM should be impaired when WM resources are reduced either by direct WM manipulation or by individual differences associated with restricted WM performance. Our study tested this prediction in school-age children by examining the independent and interactive effects of three factors known to deplete availability of WM resources: increased processing demands of a concurrent arithmetic task, additional WM span requirements, and high trait anxiety. A sample of 10-year-old children (N = 128) performed a PM task, embedded in an ongoing arithmetic task, which progressively imposed greater WM processing demands. Half of these participants also concurrently carried out an embedded WM span task. The results supported the PAM hypothesis, showing that children’s PM was compromised by the restriction of WM resources, whether this resulted from increasing the processing demands on the ongoing task, from imposing additional WM span requirements, or from high trait anxiety. However, these WM-depleting factors exerted additive effects rather than an interactive impact, suggesting that they might each deplete different aspects of WM resource availability necessary for prospective remembering. Overall findings imply that children’s PM success is not only associated to their WM capacity but it mostly depends upon how many of those WM resources are available to be devoted to the PM requirement.     

Development of reference and working spatial memory in preschool children

Three groups of preschool children (aged 18 to 28, 33 to 42, and 47 to 58 months) were given a radial search test similar to the radial arm maze used with nonhuman subjects. The children searched for chocolate sweets among 10 labeled locations in a room, 5 of which were baited with a sweet. Older children outperformed the intermediate group, who in turn outperformed the youngest group in requiring fewer choices to retrieve all of the sweets. Working memory and reference memory aspects of performance were then separated: Reference memory (restriction of choices to the baited subset) in older children was superior to that in the youngest group but not to that in the intermediate group. In terms of working memory (avoidance of repeat responses to already visited locations), the older group made fewer errors than the intermediate group, who, in turn, made fewer errors than the youngest group. We concluded that working and reference components of spatial memory in children may share common elements, perhaps the ability to recognize places as familiar, although reference memory may develop earlier than working memory.     

高功能孤独症幼儿空间工作记忆的组块加工缺陷

孤独症谱系障碍者存在空间工作记忆加工缺陷,其具体受损环节尚不明确。组块是一种有效的策略性信息编码方式,是空间工作记忆的关键环节。高度结构化的刺激容易形成高水平组块,因此,刺激结构化程度对记忆效果的影响能够反映个体的组块加工能力。研究采用Sternberg空间工作记忆任务、Corsi空间广度任务,加入刺激结构化因素,考察高功能孤独症幼儿是否存在组块加工缺陷,并探讨组块加工是否直接影响到空间工作记忆容量。实验1采用Sternberg空间工作记忆任务,结果表明,ASD幼儿存在明显的组块加工缺陷。在易于组块的高结构化条件下,健康幼儿的记忆成绩明显较高,而ASD幼儿在高、低结构化条件下的记忆成绩并无显著差异。实验2采用Corsi空间广度任务,结果显示,不论高、低结构化条件,ASD幼儿的空间工作记忆容量均显著低于健康幼儿。但ASD幼儿由于存在组块加工缺陷,在高、低结构化条件下的记忆成绩差异较健康幼儿小。因此,ASD幼儿的组块能力一定程度上影响了空间工作记忆容量。此外,记忆存储器的异常可能也是ASD幼儿空间工作记忆容量不足的重要原因。研究表明,ASD幼儿的空间组块缺陷主要由于弱中央统合的认知风格,他们缺乏自上而下的组块加工动机,难以主动对刺激形成高水平组块编码,从而影响记忆效果。