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.     

Attaching meaning to the number words: contributions of the object tracking and approximate number systems

Children's understanding of the quantities represented by number words (i.e., cardinality) is a surprisingly protracted but foundational step in their learning of formal mathematics. The development of cardinal knowledge is related to one or two core, inherent systems – the approximate number system (ANS) and the object tracking system (OTS) – but whether these systems act alone, in concert, or antagonistically is debated. Longitudinal assessments of 198 preschool children on OTS, ANS, and cardinality tasks enabled testing of two single‐mechanism (ANS‐only and OTS‐only) and two dual‐mechanism models, controlling for intelligence, executive functions, preliteracy skills, and demographic factors. Measures of both OTS and ANS predicted cardinal knowledge in concert early in the school year, inconsistent with single‐mechanism models. The ANS but not the OTS predicted cardinal knowledge later in the school year as well the acquisition of the cardinal principle, a critical shift in cardinal understanding. The results support a Merge model, whereby both systems initially contribute to children's early mapping of number words to cardinal value, but the role of the OTS diminishes over time while that of the ANS continues to support cardinal knowledge as children come to understand the counting principles.     

Object recognition in Williams syndrome: uneven ventral stream activation

Williams syndrome (WS) is a genetic disorder associated with severe visuospatial deficits, relatively strong language skills, heightened social interest, and increased attention to faces. On the basis of the visuospatial deficits, this disorder has been characterized primarily as a deficit of the dorsal stream, the occipitoparietal brain regions that subserve visuospatial processing. However, some evidence indicates that this disorder may also affect the development of the ventral stream, the occipitotemporal cortical regions that subserve face and object recognition. The present studies examined ventral stream function in WS, with the hypothesis that faces would produce a relatively more mature pattern of ventral occipitotemporal activation, relative to other objects that are also represented across these visual areas. Using functional magnetic imaging, we compared activation patterns during viewing of human faces, cat faces, houses and shoes in individuals with WS (age 14-27), typically developing 6-9-year-olds (matched approximately on mental age), and typically developing 14-26-year-olds (matched on chronological age). Typically developing individuals exhibited changes in the pattern of activation over age, consistent with previous reports. The ventral stream topography of individuals with WS differed from both control groups, however, reflecting the same level of activation to face stimuli as chronological age matches, but less activation to house stimuli than either mental age or chronological age matches. We discuss the possible causes of this unusual topography and implications for understanding the behavioral profile of people with WS.     

The approximate number system and its relation to early math achievement: Evidence from the preschool years

Humans rely on two main systems of quantification; one is nonsymbolic and involves approximate number representations (known as the approximate number system or ANS), and the other is symbolic and allows for exact calculations of number. Despite the pervasiveness of the ANS across development, recent studies with adolescents and school-aged children point to individual differences in the precision of these representations that, importantly, have been shown to relate to symbolic math competence even after controlling for general aspects of intelligence. Such findings suggest that the ANS, which humans share with nonhuman animals, interfaces specifically with a uniquely human system of formal mathematics. Other findings, however, point to a less straightforward picture, leaving open questions about the nature and ontogenetic origins of the relation between these two systems. Testing children across the preschool period, we found that ANS precision correlated with early math achievement but, critically, that this relation was nonlinear. More specifically, the correlation between ANS precision and math competence was stronger for children with lower math scores than for children with higher math scores. Taken together, our findings suggest that early-developing connections between the ANS and mathematics may be fundamentally discontinuous. Possible mechanisms underlying such nonlinearity are discussed.     

Young Mandarin learners use function words to distinguish between nouns and verbs

Mandarin requires neither determiners nor morphological inflections, which casts doubt on Mandarin‐speaking children's ability to use function words as a syntactic bootstrapping tool to identify the form class of a new word. This study examined 3‐ and 5‐year‐old Mandarin learners' ability to use function words to interpret new words as either nouns or verbs in the absence of the requirement for determiners and inflections in the ambient language. In Experiment 1, 3‐, and 5‐year‐old Mandarin‐speaking children were exposed to eight novel words embedded in sentence frames differing only in the form class markers used. The 5‐year‐olds interpreted the novel words as either nouns or verbs depending on the form class markers they heard, while the 3‐year‐olds learned only the nouns. Experiment 2 confirmed that the 5‐year‐olds understood the function of the verb‐marker. Thus, Mandarin‐speaking children can use function words to distinguish nouns versus verbs, and this ability appears between three and five years of age.     

Children's collaborative recall of shared and unshared information

This study examined age differences in collaborative inhibition and the role of inter‐subjectivity, collective information sampling (CIS) and collaborative inhibition for the collaborative recall of shared and unshared information in groups of 7‐ and 9‐year‐old children. Three‐hundred and thirteen 7‐ and 9‐year‐old children recalled memorized wordlists either in real or nominal groups of three. All group members either recalled the same items, or each group member was given some unique items. Nine‐year‐olds, but not 7‐year‐olds, recalled significantly more items in nominal than real groups, a phenomenon called collaborative inhibition. Groups whose interactions were characterized by higher numbers of inter‐subjective exchanges recalled fewer words than groups low in inter‐subjectivity. In both age groups, a higher proportion of shared compared with unshared information was recalled consistent with processes of CIS. However, 7‐year‐olds recalled more unshared items than predicted, suggesting that collaborative inhibition additionally contributes to the recall of shared and unshared items.     

Educational and interpersonal uses of home computers by adolescents with and without specific language impairment

Many uses of new media entail processing language content, yet little is known about the relationship between language ability and media use in young people. This study compares educational versus interpersonal uses of home computers in adolescents with and without a history of specific language impairment (SLI). Participants were 55 17‐year‐olds with SLI and 72 typically developing peers. Measures of frequency and ease of computer use were obtained as well as assessments of participants' psycholinguistic skills. Results showed a strong preference for interpersonal computer use in both groups. Virtually all participants engaged with interpersonal new media, finding them relatively easy to use. In contrast, one third of adolescents with SLI did not use educational applications during a typical week. Regression analyses revealed that lower frequency of educational use was associated with poorer language and literacy skills. However, in adolescents with SLI, this association was mediated by perceived ease of use. The findings show that language ability contributes to new media use and that adolescents with SLI are at a greater risk of low levels of engagement with educational technology.     

Orientation perception in Williams Syndrome: Discrimination and integration

Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 and causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3–4 year olds had similar orientation discrimination thresholds and had similar prevalence of mirror-reversal errors for diagonal targets (±45 deg). In Experiment 2, we asked whether this immaturity in orientation discrimination would also be reflected in a task requiring integration of oriented elements. We found that sensitivities of WS individuals for detecting orientation-defined contours were higher than sensitivities of normal 3–4 year olds, and were not significantly different from sensitivities of normal adults. Together, these results suggest that orientation discrimination and orientation integration have different maturational trajectories in normal development and different susceptibilities to damage in WS. These may reflect largely separate visuospatial mechanisms.     

Older but not younger infants associate own‐race faces with happy music and other‐race faces with sad music

We used a novel intermodal association task to examine whether infants associate own‐ and other‐race faces with music of different emotional valences. Three‐ to 9‐month‐olds saw a series of neutral own‐ or other‐race faces paired with happy or sad musical excerpts. Three‐ to 6‐month‐olds did not show any specific association between face race and music. At 9 months, however, infants looked longer at own‐race faces paired with happy music than at own‐race faces paired with sad music. Nine‐month‐olds also looked longer at other‐race faces paired with sad music than at other‐race faces paired with happy music. These results indicate that infants with nearly exclusive own‐race face experience develop associations between face race and music emotional valence in the first year of life. The potential implications of such associations for developing racial biases in early childhood are discussed.     

Assessment of Working Memory Capacity in Preschool Children Using the Missing Scan Task

The purpose of this study was to investigate the feasibility and validity of a modified version of Buschke's missing scan methodology, the Missing Scan Task (MST), to assess working memory capacity (WMC) and cognitive control processes in preschool children 3–6 years in age. Forty typically developing monolingual English‐speaking children between 36 and 84 months in age participated in the study. The children were tested on measures of WMC (MST), verbal and nonverbal memory (NEPSY Narrative Memory and Memory for Designs subtests), and language skills (Peabody Picture Vocabulary Test, fourth edition). Children showed increased working memory capacity scores with age, as measured by the MST, with significant differences between 3‐ and 5‐year‐olds and 3‐ and 6‐year‐olds. Significant correlations were also found between the MST and language and verbal and nonverbal memory scores. MST scores still remained significantly correlated with the other measures of memory even after age and global language were accounted for in a regression analysis, demonstrating that the MST captures unique variance related specifically to WMC and cognitive control processes used to retrieve and scan information in short‐term memory (STM). The results of this study demonstrate that the MST is a feasible and valid methodology for assessing WMC in preschool children as young 3 years of age. Copyright © 2014 John Wiley & Sons, Ltd.     

Lexical‐processing efficiency leverages novel word learning in infants and toddlers

Children who rapidly recognize and interpret familiar words typically have accelerated lexical growth, providing indirect evidence that lexical processing efficiency (LPE) is related to word‐learning ability. Here we directly tested whether children with better LPE are better able to learn novel words. In Experiment 1, 17‐ and 30‐month‐olds were tested on an LPE task and on a simple word‐learning task. The 17‐month‐olds’ LPE scores predicted word learning in a regression model, and only those with relatively good LPE showed evidence of learning. The 30‐month‐olds learned novel words quite well regardless of LPE, but in a more difficult word‐learning task (Experiment 2), their LPE predicted word‐learning ability. These findings suggest that LPE supports word‐learning processes, especially when learning is difficult.     

Magical thinking in judgments of causation: Can anomalous phenomena affect ontological causal beliefs in children and adults?

In four experiments, 4‐, 5‐, 6‐ and 9‐year‐old children and adults were tested on the entrenchment of their magical beliefs and their beliefs in the universal power of physical causality. In Experiment 1, even 4‐year‐olds showed some understanding of the difference between ordinary and anomalous (magical) causal events, but only 6‐year‐olds and older participants denied that magic could occur in real life. When shown an anomalous causal event (a transformation of a physical object in an apparently empty box after a magic spell was cast on the box), 4‐ and 6‐year‐olds accepted magical explanations of the event, whereas 9‐year‐olds and adults did not. In Experiment 2, the same patterns of behaviour as above were shown by 6‐ and 9‐year‐olds who demonstrated an understanding of the difference between genuine magical events and similarly looking tricks. Testing the entrenchment of magical beliefs in this experiment showed that 5‐year‐olds tended to retain their magical explanations of the anomalous event, even after the mechanism of the trick had been explained to them, whereas 6‐ and 9‐year‐olds did not. In Experiment 3, adult participants refused to accept magical explanations of the anomalous event and interpreted it as a trick or an illusion, even after this event was repeated 4 times. Yet, when in Experiment 4 similar anomalous causal events were demonstrated without reference to magic, most adults acknowledged, both in their verbal judgments and in their actions, that the anomalous effects were not a fiction but had really occurred. The data of this study suggest that in the modern industrialized world, magical beliefs persist but are disguised to fit the dominant scientific paradigm.     

Enculturation to musical pitch structure in young children: evidence from behavioral and electrophysiological methods

Children learn the structure of the music of their culture similarly to how they learn the language to which they are exposed in their daily environment. Furthermore, as with language, children acquire this musical knowledge without formal instruction. Two critical aspects of musical pitch structure in Western tonal music are key membership (understanding which notes belong in a key and which do not) and harmony (understanding which notes combine to form chords and which notes and chords tend to follow others). The early developmental trajectory of the acquisition of this knowledge remains unclear, in part because of the difficulty of testing young children. In two experiments, we investigated 4‐ and 5‐year‐olds' enculturation to Western musical pitch using a novel age‐appropriate and engaging behavioral task (Experiment 1) and electroencephalography (EEG; Experiment 2). In Experiment 1 we found behavioral evidence that 5‐year‐olds were sensitive to key membership but not to harmony, and no evidence that 4‐year‐olds were sensitive to either. However, in Experiment 2 we found neurophysiological evidence that 4‐year‐olds were sensitive to both key membership and harmony. Our results suggest that musical enculturation has a long developmental trajectory, and that children may have some knowledge of key membership and harmony before that knowledge can be expressed through explicit behavioral judgments.     

On‐line ostracism affects children differently from adolescents and adults

This research examines adults', and for the first time, children's and adolescents' reaction to being ostracized and included, using an on‐line game, ‘Cyberball’ with same and opposite sex players. Ostracism strongly threatened four primary needs (esteem, belonging, meaning, and control) and lowered mood among 8‐ to 9‐year‐olds, 13‐ to 14‐year‐olds, and adults. However, it did so in different ways. Ostracism threatened self‐esteem needs more among 8‐ to 9‐year‐olds than older participants. Among 13‐ to 14‐year‐olds, ostracism threatened belonging more than other needs. Belonging was threatened most when ostracism was participants' first experience in the game. Moreover, when participants had been included beforehand, ostracism threatened meaning needs most strongly. Gender of other players had no effect. Practical and developmental implications for social inclusion and on‐line experiences among children and young people are discussed.     

Children's intuitive sense of number develops independently of their perception of area,density, length,and time

Young children can quickly and intuitively represent the number of objects in a visual scene through the Approximate Number System (ANS). The precision of the ANS – indexed as the most difficult ratio of two numbers that children can reliably discriminate – is well known to improve with development: whereas infants require relatively large ratios to discriminate number, children can discriminate finer and finer changes in number between toddlerhood and early adulthood. Which factors drive the developmental improvements in ANS precision? Here, we investigate the influence of four non‐numeric dimensions – area, density, line length, and time – on ANS development, exploring the degree to which the ANS develops independently from these other dimensions, from inhibitory control, and from domain‐general factors such as attention and working memory that are shared between these tasks. A sample of 185 children between the ages of 2 and 12 years completed five discrimination tasks: approximate number, area, density, length, and time. We report three main findings. First, logistic growth models applied to both accuracy and Weber fractions (w; an index of ANS precision) across age reveal distinct developmental trajectories across the five dimensions: while area and length develop by adolescence, time and density do not develop fully until early adulthood, with ANS precision developing at an intermediate rate. Second, we find that ANS precision develops independently of the other four dimensions, which in turn develop independently of the ANS. Third, we find that ANS precision also develops independently from individual differences in inhibitory control (indexed as the difference in accuracy and w between Congruent and Incongruent ANS trials). Together, these results are the first to provide evidence for domain‐specific improvements in ANS precision, and place children's maturing perception of number, space, and time into a broader developmental context.     

Children's expectations about training the approximate number system

Humans possess a developmentally precocious and evolutionarily ancient approximate number system (ANS) whose sensitivity correlates with uniquely human symbolic arithmetic skills. Recent studies suggest that ANS training improves symbolic arithmetic, but such studies may engender performance expectations in their participants that in turn produce the improvement. Here, we assessed 6‐ to 8‐year‐old children's expectations about the effects of numerical and non‐numerical magnitude training, as well as states of satiety and restfulness, in the context of a study linking children's ANS practice to their improved symbolic arithmetic. We found that children did not expect gains in symbolic arithmetic after exercising the ANS, although they did expect gains in ANS acuity after training on any magnitude task. Moreover, children expected gains in symbolic arithmetic after a good night's sleep and their favourite breakfast. Thus, children's improved symbolic arithmetic after ANS training cannot be explained by their expectations about that training.     

Learning without representational change: development of numerical estimation in individuals with Williams syndrome

Experience engenders learning, but not all learning involves representational change. In this paper, we provide a dramatic case study of the distinction between learning and representational change. Specifically, we examined long‐ and short‐term changes in representations of numeric magnitudes by asking individuals with Williams syndrome (WS) and typically developing (TD) children to estimate the position of numbers on a number line. As with TD children, accuracy of WS children's numerical estimates improved with age (Experiment 1) and feedback (Experiment 2). Both long‐ and short‐term changes in estimates of WS individuals, however, followed an atypical developmental trajectory: as TD children gained in age and experience, increases in accuracy were accompanied by a logarithmic‐to‐linear shift in estimates of numerical magnitudes, whereas in WS individuals, accuracy increased but logarithmic estimation patterns persisted well into adulthood and after extensive training. These findings suggest that development of numerical estimation in WS is both arrested and atypical.     

Complex and subtle structural changes in prefrontal cortex induced by inhibitory control training from childhood to adolescence

A number of training interventions have been designed to improve executive functions and inhibitory control (IC) across the lifespan. Surprisingly, no study has investigated the structural neuroplasticity induced by IC training from childhood to late adolescence, a developmental period characterized by IC efficiency improvement and protracted maturation of prefrontal cortex (PFC) subregions involved in IC. The aim of the present study was to investigate the behavioral and structural changes induced by a 5‐week computerized and adaptive IC training in school‐aged children (10‐year‐olds) and in adolescents (16‐year‐olds). Sixty‐four children and 59 adolescents were randomly assigned to an IC (i.e. Color‐Word Stroop and Stop‐Signal tasks) or an active control (AC) (knowledge‐ and vocabulary‐based tasks) training group. In the pre‐ and posttraining sessions, participants performed the Color‐Word Stroop and Stop‐signal tasks, and an anatomical resonance imaging (MRI) was acquired for each of them. Children's IC efficiency improved from the pre‐ to the posttraining session in boys but not in girls. In adolescents, IC efficiency did not improve after IC training. Similar to the neuroplastic mechanisms observed during brain maturation, we observed IC training‐related changes in cortical thickness and cortical surface area in several PFC subregions (e.g. the pars opercularis, triangularis, and orbitalis of the inferior frontal gyri) that were age‐ and gender‐specific. Because no correction for multiple comparisons was applied, the results of our study provide only preliminary evidence of the complex structural neuroplastic mechanisms at the root of behavioral changes in IC efficiency from pre‐ to posttraining in school‐aged children and adolescents.     

To be or not to be a galaprock: Preschoolers' intuitions about the importance of knowledge and action for pretending

Can someone pretend to be a galaprock without knowing what a galaprock is? Do children recognize that such knowledge is required for pretending? Three studies focusing on the relations among action, knowledge and pretending suggest that children have this understanding by age 4 years. In Study 1, 4‐year‐olds and adults willingly pretended to be moving and unmoving objects but had trouble pretending to be objects that were difficult to represent physically. In Study 2, 3‐ and 4‐year‐olds claimed they could not pretend to be an unknown thing, justifying their refusals with mentalistic language indicating their ignorance of the object or its typical actions. In Study 3, 3‐ to 5‐year‐olds predicted that other children who have knowledge of an object unfamiliar to the subjects themselves can nevertheless pretend to be it, whereas those lacking that knowledge cannot. The results add support to the growing literature showing that preschoolers conceptualize pretense as involving mental activity.     

The interplay between executive control and motor functioning in Williams syndrome

Previous studies suggest that individuals with Williams syndrome (WS), a rare genetically based neurodevelopmental disorder, show specific weaknesses in visual attention and response inhibition within the visuospatial domain. Here we examine the extent to which impairments in attentional control extend to the visuomotor domain using a well‐validated measure of choice stepping reaction time (CSRT) in individuals with WS. We examined the interaction between executive control and visually guided stepping using a verbal fluency dual‐task or Go/NoGo paradigm during CSRT performance. Relationships between dual‐task and inhibitory stepping and behavioural inattention and hyperactivity were also examined. Our results showed clear dual‐task costs in stepping response times when performing a concurrent cognitive task in the WS group when compared to spatial and verbal ability matched typically developing controls. Although no group differences in stepping accuracy were observed between the WS and typically developing control groups, the WS group showed progressive slowing and more variable response times across the duration of the Go/NoGo task. These results suggest dysfunction in circuits involved in top‐down attentional control processes in WS. These findings provide novel evidence that core executive control deficits in WS extend to the visuomotor domain, and impact on ADHD‐related inattentive symptoms.