Language, space, and the development of cognitive flexibility in humans: the case of two spatial memory tasks

Prior experiments have shown that young children, like adult rats, rely mainly on information about the macroscopic shape of the environment to reorient themselves, whereas human adults rely more flexibly on combinations of spatial and non-spatial landmark information. Adult rats have also been shown to exhibit a striking limitation in another spatial memory task, movable object search, again a limitation not shown by human adults. The present experiments explored the developmental change in humans leading to more flexible, human adult-like performance on these two tasks. Experiment 1 identified the age range of 5-7 years as the time the developmental change for reorientation occurs. Experiment 2 employed a multiple regression approach to determine that among several candidate measures, only a specific language production measure, the production of phrases specifying exactly the information needed to solve the task like adults, correlated with the reorientation performance of children in this age range. Experiment 3 revealed that similar language production abilities were associated with more flexible moving object search task performance. These results, in combination with findings with human adults, suggest that language production skills play a causal role in allowing older humans to construct novel representations rapidly, which can then be used to transcend the limits of phylogenetically older cognitive processes.     

Developmental profiles for multiple object tracking and spatial memory: typically developing preschoolers and people with Williams syndrome

The ability to track moving objects, a crucial skill for mature performance on everyday spatial tasks, has been hypothesized to require a specialized mechanism that may be available in infancy (i.e. indexes). Consistent with the idea of specialization, our previous work showed that object tracking was more impaired than a matched spatial memory task in individuals with Williams syndrome (WS), a genetic disorder characterized by severe visuo‐spatial impairment. We now ask whether this unusual pattern of performance is a reflection of general immaturity or of true abnormality, possibly reflecting the atypical brain development in WS. To examine these two possibilities, we tested typically developing 3‐ and 4‐year‐olds and people with WS on multiple object tracking (MOT) and memory for static spatial location. The maximum number of objects that could be correctly tracked or remembered (estimated from the k‐statistic) showed similar developmental profiles in typically developing 3‐ and 4‐year‐old children, but the WS profile differed from either age group. People with WS could track more objects than 3‐year‐olds, and the same number as 4‐year‐olds, but they could remember the locations of more static objects than both 3‐ and 4‐year‐olds. Combining these data with those from our previous studies, we found that typically developing children show increases in the number of objects they can track or remember between the ages of 3 and 6, and these increases grow in parallel across the two tasks. In contrast, object tracking in older children and adults with WS remains at the level of 4‐year‐olds, whereas the ability to remember multiple locations of static objects develops further. As a whole, the evidence suggests that MOT and memory for static location develop in tandem typically, but not in WS. Atypical development of the parietal lobe in people with WS could play a causal role in the abnormal, uneven pattern of performance in WS. This interpretation is consistent with the idea that multiple object tracking engages different mechanisms from those involved in memory for static object location, and that the former can be particularly disrupted by atypical development.     

Developmental trajectories for spatial frames of reference in Williams syndrome

Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body-, environment-, and object-based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body- and environment-based frames of reference. Crucially, object-based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark-based representations supplement those based on the body and on self-motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.     

The role of landmarks and boundaries in the development of spatial memory

It has been suggested that learning an object's location relative to (1) intramaze landmarks and (2) local boundaries is supported by parallel striatal and hippocampal systems, both of which rely upon input from a third system for orientation. However, little is known about the developmental trajectories of these systems' contributions to spatial learning. The present study tested 5- and 7-year-old children and adults on a water maze-like task in which all three types of cue were available. Participants had to remember the location of an object hidden in a circular bounded environment containing a moveable intramaze landmark and surrounded by distal cues. Children performed less accurately than adults, and showed a different pattern of error. While adults relied most on the stable cue provided by the boundary, children relied on both landmark and boundary cues similarly, suggesting a developmental increase in the weighting given to boundary cues. Further, adults were most accurate in coding angular information (dependent on distal cues), whereas children were most accurate in coding distance, suggesting a developing ability to use distal cues to orient. These results indicate that children as young as 5 years use boundary, intramaze landmark, and distal visual cues in parallel, but that the basic accuracy and relative weighting of these cues changes during subsequent development.     

边界促进空间导航的认知神经机制

边界是指在人的视野中占据较大比例,且具有立体拓展平面的障碍物,对于人类和动物的空间导航行为具有极大的促进作用。认知发展研究发现儿童早期(1岁半～2岁)通过加工边界的空间几何结构实现物体定位,并且随着年龄的发展逐渐学会利用边界的高度信息(3.1岁～4.7岁)、长度信息(4～5岁)、视觉阻碍性信息(5岁)等完成空间导航。基于这些认知过程,神经影像学研究主要以成人为研究被试,发现大脑中的内侧颞叶和顶叶脑区在边界加工中有着不同功能作用。具体而言,边界的空间几何结构及构成要素(高度、长度和角度)体位置的学习和提取则由海马负责。但是,仍存在一些研究问题值得未来深入S探c讨i。e第n一c,e拓展深化边界促进与后顶叶之间的功能交互。第三,密切关注大脑对场地边界与场地中心编码的心理或神经表征的区别和联系。第四,重点考察阿尔兹海默症有关基因易感人群在基于边界导航的行为受损情况。最后,延伸探讨边界在长时记忆、时间知觉、视觉空间、社交网络等领域的影响机制。     

Early indications of delayed cognitive development in preschool children born very preterm: evidence from domain‐general and domain‐specific tasks

Cognitive impairment often follows preterm birth but its early underlying nature is not well understood. We used a novel approach by investigating the development of colour cognition in 54 very preterm children born ?30 weeks gestational age without severe neurosensory impairment and 37 age‐matched term‐born controls, aged 2–5 years. Quantitative and qualitative differences in the development of colour cognition are well charted throughout the preschool years, enabling delayed from deviant development to be determined. Standardized domain‐general and experimental colour‐specific tests of language, attention, and memory were employed. Very preterm children showed significantly depressed language than term controls, with very preterm group girls significantly outperforming boys. Very preterm children also showed poorer attention and memory than term controls, but not significantly so. Importantly, colour‐specific tests showed qualitatively similar performance, but for naming and executive planning quantitatively poorer performance, across groups, indicating typical but delayed development. Hence, even before school entry, compared with term‐born peers, very preterm children show delayed development of cognitive processes that underpin later scholastic abilities, but the nature by which these processes operate appears to be typical of term children. If left untreated these early developmental delays may underpin later deviations from the typical developmental trajectory. Copyright © 2010 John Wiley & Sons, Ltd.     

Switching from reaching to navigation: differential cognitive strategies for spatial memory in children and adults

Navigational and reaching spaces are known to involve different cognitive strategies and brain networks, whose development in humans is still debated. In fact, high‐level spatial processing, including allocentric location encoding, is already available to very young children, but navigational strategies are not mature until late childhood. The Magic Carpet (MC) is a new electronic device translating the traditional Corsi Block‐tapping Test (CBT) to navigational space. In this study, the MC and the CBT were used to assess spatial memory for navigation and for reaching, respectively. Our hypothesis was that school‐age children would not treat MC stimuli as navigational paths, assimilating them to reaching sequences. Ninety‐one healthy children aged 6 to 11 years and 18 adults were enrolled. Overall short‐term memory performance (span) on both tests, effects of sequence geometry, and error patterns according to a new classification were studied. Span increased with age on both tests, but relatively more in navigational than in reaching space, particularly in males. Sequence geometry specifically influenced navigation, not reaching. The number of body rotations along the path affected MC performance in children more than in adults, and in women more than in men. Error patterns indicated that navigational sequences were increasingly retained as global paths across development, in contrast to separately stored reaching locations. A sequence of spatial locations can be coded as a navigational path only if a cognitive switch from a reaching mode to a navigation mode occurs. This implies the integration of egocentric and allocentric reference frames, of visual and idiothetic cues, and access to long‐term memory. This switch is not yet fulfilled at school age due to immature executive functions.     

Memory abilities in Williams syndrome: Dissociation or developmental delay hypothesis?

Williams syndrome (WS) is a neurodevelopmental genetic disorder often described as being characterized by a dissociative cognitive architecture, in which profound impairments of visuo-spatial cognition contrast with relative preservation of linguistic, face recognition and auditory short-memory abilities. This asymmetric and dissociative cognition has been also proposed to characterize WS memory ability, with sparing of auditory short-term memory and impairment of spatial and long-term memory abilities. In this study, we explored the possibility of a double memory dissociation in WS (short- versus long-term memory; verbal versus visual memory). Thus, verbal memory abilities were assessed using California Verbal Learning Test and Digit Span and Rey-Osterrieth Complex Figure and Corsi Blocks was used to assess visual-spatial memory abilities. Overall, WS subjects were found to present a generalized significant impairment in verbal and visuo-spatial components either in short- or long-term memory. In sum, data from this study brings support for a developmental delay hypothesis, rather than a double dissociation within memory systems in WS.     

Developmental Changes in Young Children's Spatial Memory and Language in Relation to Landmarks

Two experiments investigated how young children and adults understand whether objects are by a landmark and remember their locations. Three- and 4-year-old children and adults were asked to judge whether several blocks were by a landmark. The blocks were arranged so that their absolute and relative distances from the landmark varied. Later, the blocks were removed, and participants were asked to place them in their original locations. All ages relied on relative distance between objects and a landmark when making by judgments; however, older children and adults showed systematic judgments. Relative distance also affected block placement, and systematicity increased across development. Children's understanding of the relative nature of by and their ability to remember locations precisely increased during the preschool years, indicating developmental changes in the adaptive combination of location cues for spatial language and memory.     

Anticipatory scene representation in preschool children's recall and recognition memory

Behavioral and neuroscience research on boundary extension (false memory beyond the edges of a view of a scene) has provided new insights into the constructive nature of scene representation, and motivates questions about development. Early research with children (as young as 6–7 years) was consistent with boundary extension, but relied on an analysis of spatial errors in drawings which are open to alternative explanations (e.g. drawing ability). Experiment 1 replicated and extended prior drawing results with 4–5‐year‐olds and adults. In Experiment 2, a new, forced‐choice immediate recognition memory test was implemented with the same children. On each trial, a card (photograph of a simple scene) was immediately replaced by a test card (identical view and either a closer or more wide‐angle view) and participants indicated which one matched the original view. Error patterns supported boundary extension; identical photographs were more frequently rejected when the closer view was the original view, than vice versa. This asymmetry was not attributable to a selection bias (guessing tasks; Experiments 3–5). In Experiment 4, working memory load was increased by presenting more expansive views of more complex scenes. Again, children exhibited boundary extension, but now adults did not, unless stimulus duration was reduced to 5 s (limiting time to implement strategies; Experiment 5). We propose that like adults, children interpret photographs as views of places in the world; they extrapolate the anticipated continuation of the scene beyond the view and misattribute it to having been seen. Developmental differences in source attribution decision processes provide an explanation for the age‐related differences observed.     

Executive function in paediatric medulloblastoma: The role of cerebrocerebellar connections

Executive functions (EFs) are involved in the attainment, maintenance, and integration of information; these functions may play a key role in cognitive and behavioural outcomes in children treated for medulloblastoma (MB). At present, it remains unclear which EFs are most sensitive to the treatment effects for MB and whether damage to cerebrocerebellar circuitry is associated with EF. We completed a comprehensive evaluation of EF in 24 children treated for MB and 20 age‐matched healthy children (HC) and distilled these measures into components. Six components (C1–C6) were extracted from our model, reflecting dissociable constructs of EF: C1 = cognitive efficiency; C2 = planning/problem‐solving; C3 = positive cognitive emotion regulation; C4 = working memory; C5 = negative cognitive emotion regulation; and C6 = mixed cognitive emotion regulation. Group differences were found for C1, C2, C3, and C4; the MB group showed poorer performance on EF tasks and made less use of positive cognitive emotion regulation strategies relative to HC. Compromise to cerebrocerebellar microstructure – cerebro‐ponto‐cerebellar and cerebello‐thalamo‐cerebral pathways – was evident in children treated for MB compared to HC. We found that cerebrocerebellar circuitry has a mediating effect on one component of EF following treatment for MB – working memory.     

Egocentric and allocentric navigation strategies in Williams syndrome and typical development

Recent findings suggest that difficulties on small‐scale visuospatial tasks documented in Williams syndrome (WS) also extend to large‐scale space. In particular, individuals with WS often present with difficulties in allocentric spatial coding (encoding relationships between items within an environment or array). This study examined the effect of atypical spatial processing in WS on large‐scale navigational strategies, using a novel 3D virtual environment. During navigation of recently learnt large‐scale space, typically developing (TD) children predominantly rely on the use of a sequential egocentric strategy (recalling the sequence of left–right body turns throughout a route), but become more able to use an allocentric strategy between 5 and 10 years of age. The navigation strategies spontaneously employed by TD children between 5 and 10 years of age and individuals with WS were analysed. The ability to use an allocentric strategy on trials where spatial relational knowledge was required to find the shortest route was also examined. Results showed that, unlike TD children, during spontaneous navigation the WS group did not predominantly employ a sequential egocentric strategy. Instead, individuals with WS followed the path until the correct environmental landmarks were found, suggesting the use of a time‐consuming and inefficient view‐matching strategy for wayfinding. Individuals with WS also presented with deficits in allocentric spatial coding, demonstrated by difficulties in determining short‐cuts when required and difficulties developing a mental representation of the environment layout. This was found even following extensive experience in an environment, suggesting that – unlike in typical development – experience cannot contribute to the development of spatial relational processing in WS. This atypical presentation of both egocentric and allocentric spatial encoding is discussed in relation to specific difficulties on small‐scale spatial tasks and known atypical cortical development in WS.     

The development of route learning in Down syndrome,Williams syndrome and typical development: investigations with virtual environments

The ability to navigate new environments has a significant impact on the daily life and independence of people with learning difficulties. The aims of this study were to investigate the development of route learning in Down syndrome (N = 50), Williams syndrome (N = 19), and typically developing children between 5 and 11 years old (N = 108); to investigate use of landmarks; and to relate cognitive functions to route‐learning ability in these groups. Overall, measures of attention and long‐term memory were strongly associated with route learning, even once non‐verbal ability was controlled for. All of the groups, including 5‐ to 6‐year‐old TD children, demonstrated the ability to make use of all landmark types to aid route learning; those near junctions, those further from junctions, and also distant landmarks (e.g. church spire, radio mast). Individuals with WS performed better than a matched subset of TD children on more difficult routes; we suggest that this is supported by relatively strong visual feature recognition in the disorder. Participants with DS who had relatively high levels of non‐verbal ability performed at a similar level to TD participants.     

The effect of experience on children's ability to show response and place learning

From a developmental perspective, it has been reasoned that over the course of development children make differential use of available landmarks in the surroundings to orient in space. The present study examined whether children can learn to apply different spatial strategies, focusing on different landmark cues. Children aged 7 and 10 years were tested on an object‐location memory task in which they learned a location relative to a direct cue or to indirect cues. Both age groups performed equally well on the direct test condition. However, children 7 years of age had difficulties with orienting relative to the indirect landmarks. Interestingly, their performance increased significantly with more relevant experience. Different explanations for these findings are discussed.     

Developmental differences in memory for cross‐modal associations

Associative learning is critical to normal cognitive development in children. However, young adults typically outperform children on paired‐associate tasks involving visual, verbal and spatial location stimuli. The present experiment investigated cross‐modal odour–place associative memory in children (7–10 years) and young adults (18–24 years). During the study phase, six odours were individually presented and paired with one of 12 spatial locations on a board. During the test phase, participants were presented with the six stimuli individually and were asked to place each stimulus on the correct spatial location. Children committed significantly more errors on the odour–place task than did young adults. However, item recognition memory for the odours or spatial locations involved in the odour–place associative memory task was similar between children and young adults. Therefore, poor odour–place associative memory in children did not result from impaired memory for the individual odours or spatial locations involved in the associations. The results suggest that cross‐modal associative memory is not fully developed in children.     

Spatial knowledge of children with spina bifida in a virtual large-scale space

The spatial knowledge of 18 children with spina bifida and 18 healthy control children (matched according to sex, age, and verbal IQ) was investigated in a computer-simulated environment. All children had to learn a route through a virtual floor system containing 18 landmarks. Controlling for cognitive abilities, the results revealed that children with spina bifida showed impaired route knowledge but not an impaired landmark knowledge. Thus the results suggest that children with spina bifida are not impaired in all large-scale abilities similarly. The impairments of the children with spina bifida are more accentuated in more behaviour based measurements, which indicates a relation to the reduced mobility of the children with spina bifida.     

Identifying the nature of impairments in executive functioning and working memory of children with severe difficulties in arithmetic

An age-matched achievement-matched design was used to examine whether the executive functioning and working memory impairments exhibited by children with severe difficulties in arithmetic (SDA) are better viewed as developmental lags or as cognitive deficits. Three groups of children were included: 20 SDA children, 20 typically achieving children (CM) matched in chronological age with the SDA children, and 20 younger typically achieving children (AM) matched in achievement with the SDA group. While children with SDA did not exhibit impairments in color-word inhibition and verbal working memory, they did demonstrate impairments in shifting, quantity-digits inhibition, and visuospatial working memory. As children with SDA did not perform more poorly than their AM counterparts on any of these tasks, impairments in specific areas of executive functioning and working memory appear to reflect developmental lags rather than cognitive deficits.     

Preschoolers with Down syndrome do not yet show the learning and memory impairments seen in adults with Down syndrome

Individuals with Down syndrome (DS) exhibit a behavioral phenotype of specific strengths and weaknesses, in addition to a generalized cognitive delay. In particular, adults with DS exhibit specific deficits in learning and memory processes that depend on the hippocampus, and there is some suggestion of impairments on executive function tasks that depend on the prefrontal cortex. While these functions have been investigated in adults with DS, it is largely unclear how these processes develop in young children with DS. Here we tested preschoolers with DS and typically developing children, age‐matched on either receptive language or non‐verbal scores as a proxy for mental age (MA), on a battery of eye‐tracking and behavioral measures that have been shown to depend on the hippocampus or the prefrontal cortex. Preschoolers with DS performed equivalently to MA‐matched controls, suggesting that the disability‐specific memory deficits documented in adults with DS, in addition to a cognitive delay, are not yet evident in preschoolers with DS, and likely emerge progressively with age. Our results reinforce the idea that early childhood may be a critical time frame for targeted early intervention. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=r6GUA6my22Q&list=UU3FIcom6UpITHZOIEa8Onnw     

Understanding the mapping between numerical approximation and number words: evidence from Williams syndrome and typical development

All numerate humans have access to two systems of number representation: an exact system that is argued to be based on language and that supports formal mathematics, and an Approximate Number System (ANS) that is present at birth and appears independent of language. Here we examine the interaction between these two systems by comparing the profiles of people with Williams syndrome (WS) with those of typically developing children between ages 4 and 9 years. WS is a rare genetic deficit marked by fluent and well‐structured language together with severe spatial deficits, deficits in formal math, and abnormalities of the parietal cortex, which is thought to subserve the ANS. One of our tasks, requiring approximate number comparison but no number words, revealed that the ANS precision of adolescents with WS was in the range of typically developing 2‐ to 4‐year‐olds. Their precision improved with age but never reached the level of typically developing 6‐ or 9‐year‐olds. The second task, requiring verbal number estimation using number words, revealed that the estimates produced by adolescents with WS were comparable to those of typically developing 6‐ and 9‐year‐olds, i.e. were more advanced than their ANS precision. These results suggest that ANS precision is somewhat separable from the mapping between approximate numerosities and number words, as the former can be severely damaged in a genetic disorder without commensurate impairment in the latter.