Changes to a scene often go unnoticed if the objects of the change are unattended, making change detection an index of where attention is focused during scene perception. We measured change detection in school-age children and young adults by repeatedly alternating two versions of an image. To provide an age-fair assessment we used a bimanual choice rather than open-ended verbal responses. The difference in detection speed and accuracy between 50-ms versus 250-ms blank screens between views indexed change detection in short-term visual memory independent of sensory and response processes. Younger children were significantly less efficient than older participants, especially when an object changed color or had a part deleted. Changes in object orientation were detected more readily. These results point to important differences in the perceptual reality of younger and older children.
Theories of autism have proposed that a bias towards low-level perceptual information, or a featural/surface-biased information-processing style, may compromise higher-level language processing in such individuals. Two experiments, utilizing linguistic stimuli with competing low-level/perceptual and high-level/semantic information, tested processing biases in children with autism and matched controls. Whereas children with autism exhibited superior perceptual processing of speech relative to controls, and showed no evidence of either a perceptual or semantic processing bias, controls showed a tendency to process speech semantically. The data provide partial support to the perceptual theories of autism. It is additionally proposed that the pattern of results may reflect different patterns of attentional focusing towards single or multiple stimulus cues in speech between children with autism and controls.
English-learning 7.5-month-olds are heavily biased to perceive stressed syllables as word onsets. By 11 months, however, infants begin segmenting non-initially stressed words from speech. Using the same artificial language methodology as Johnson and Jusczyk (2001), we explored the possibility that the emergence of this ability is linked to a decreased reliance on prosodic cues to word boundaries accompanied by an increased reliance on syllable distribution cues. In a baseline study, where only statistical cues to word boundaries were present, infants exhibited a familiarity preference for statistical words. When conflicting stress cues were added to the speech stream, infants exhibited a familiarity preference for stress as opposed to statistical words. This was interpreted as evidence that 11-month-olds weight stress cues to word boundaries more heavily than statistical cues. Experiment 2 further investigated these results with a language containing convergent cues to word boundaries. The results of Experiment 2 were not conclusive. A third experiment using new stimuli and a different experimental design supported the conclusion that 11-month-olds rely more heavily on prosodic than statistical cues to word boundaries. We conclude that the emergence of the ability to segment non-initially stressed words from speech is not likely to be tied to an increased reliance on syllable distribution cues relative to stress cues, but instead may emerge due to an increased reliance on and integration of a broad array of segmentation cues.
Abstract Behavioral data establish a dramatic change in infants' phonetic perception between 6 and 12 months of age. Foreign-language phonetic discrimination significantly declines with increasing age. Using a longitudinal design, we examined the electrophysiological responses of 7- and 11-month-old American infants to native and non-native consonant contrasts. Analyses of the event-related potentials (ERP) of the group data at 7 and at 11 months of age demonstrated that infants' discriminatory ERP responses to the non-native contrast are present at 7 months of age but disappear by 11 months of age, consistent with the behavioral data reported in the literature. However, when the same infants were divided into subgroups based on individual ERP components, we found evidence that the infant brain remains sensitive to the non-native contrast at 11 months of age, showing differences in either the P150-250 or the N250-550 time window, depending upon the subgroup. Moreover, we observed an increase in infants' responsiveness to native language consonant contrasts over time. We describe distinct neural patterns in two groups of infants and suggest that their developmental differences may have an impact on language development.
Twelve- and 14-month-old infants' ability to represent another person's visual perspective (Level-1 visual perspective taking) was studied in a looking-time paradigm. Fourteen-month-olds looked longer at a person reaching for and grasping a new object when the old goal-object was visible than when it was invisible to the person (but visible to the infant). These findings are consistent with the interpretation that infants 'rationalized' the person's reach for a new object when the old goal-object was out of sight. Twelve-month-olds did not distinguish between test conditions. The present findings are consistent with recent research on infants' developing understanding of seeing.
Although there is much research on infants' ability to orient in space, little is known regarding the information they use to do so. This research uses a rotating room to evaluate the relative contribution of visual and vestibular information to location of a target following bodily rotation. Adults responded precisely on the basis of visual flow information. Seven-month-olds responded mostly on the basis of visual flow, whereas 9-month-olds responded mostly on the basis of vestibular information, and 12-month-olds responded mostly on the basis of visual information. Unlike adults, infants of all ages showed partial influence by both modalities. Additionally, 7-month-olds were capable of using vestibular information when there was no visual information for movement or stability, and 9-month-olds still relied on vestibular information when visual information was enhanced. These results are discussed in the context of neuroscientific evidence regarding visual-vestibular interaction, and in relation to possible changes in reliance on visual and vestibular information following acquisition of locomotion.
Previous research has revealed that infants can reason correctly about single-event probabilities with small but not large set sizes (Bonatti, 2008; Teglas et al., 2007). The current study asks whether infants can make predictions regarding single-event probability with large set sizes using a novel procedure. Infants completed two trials: A preference trial to determine whether they preferred pink or black lollipops and a test trial where infants saw two jars, one containing mostly pink lollipops and another containing mostly black lollipops. The experimenter removed one occluded lollipop from each jar and placed them in two separate opaque cups. Seventy-eight percent of infants searched in the cup that contained a lollipop from the jar with a higher proportion of their preferred color object, significantly better than chance. Thus infants can reason about single-event probabilities with large set sizes in a choice paradigm, and contrary to most findings in the infant literature, the prediction task used here appears a more sensitive measure than the standard looking-time task.
There is increasing interest in neurobiological methods for investigating the shared representation of action perception and production in early development. We explored the extent and regional specificity of EEG desynchronization in the infant alpha frequency range (6-9 Hz) during action observation and execution in 14-month-old infants. Desynchronization during execution was restricted to central electrode sites, while action observation was associated with a broader desynchronization across frontal, central, and parietal regions. The finding of regional specificity in the overlap between EEG responses to action execution and observation suggests that the rhythm seen in the 6-9 Hz range over central sites in infancy shares certain properties with the adult mu rhythm. The magnitude of EEG desynchronization to action perception and production appears to be smaller for infants than for adults and older children, suggesting developmental change in this measure.
Adaptive behavior requires focusing on relevant tasks while remaining sensitive to novel information. In adult studies of cognitive control, cognitive stability involves maintaining robust cognitive representations while cognitive flexibility involves updating of representations in response to novel information. Previous adult research has shown that the Met allele of the COMT Val(158) Met gene is associated with enhanced cognitive stability whereas the Val allele is associated with enhanced cognitive flexibility. Here we propose that the stability/flexibility framework can also be applied to infant research, with stability mapping onto early indices of behavioral regulation and flexibility mapping onto indices of behavioral reactivity. From this perspective, the present study examined whether COMT genotype was related to 7-month-old infants' reactivity to novel stimuli and behavioral regulation. Cognitive stability and flexibility were assessed using (1) a motor approach task, (2) a habituation task, and (3) a parental-report measure of temperament. Val carriers were faster to reach for novel toys during the motor approach task and received higher scores on the temperament measure of approach to novelty. Met carriers showed enhanced dishabituation to the novel stimulus during the habituation task and received higher scores on the temperament measures of sustained attention and behavioral regulation. Overall, these results are consistent with adult research suggesting that the Met and Val alleles are associated with increased cognitive stability and flexibility, respectively, and thus suggest that COMT genotype may similarly affect cognitive function in infancy.
Absent reference comprehension is a critical achievement of early development, yet little is known about its emergence. In the current study, 12- and 16-month-old infants' recognition of properties of mentioned absent things was used as an index of absent reference comprehension. Infants were presented with displays matching the color and prior spatial location of a mentioned absent object and displays matching the color and prior spatial location of a non-mentioned absent object. Infants could reveal their comprehension of absent reference by directing more looking and gesturing at the display matching the mentioned absent object than at the display matching the non-mentioned absent object. Infants at both ages revealed some tendency to do so, but infants at 16 months revealed more advanced understanding--infants at 16 months, but not at 12 months, coordinated their attention to the display matching properties of the mentioned absent thing with looks to the speaker. Implications for the infants' understanding of communicative intentions are discussed.
In the context of an imitation game, 12- and 18-month-old infants saw an adult do such things as make a toy mouse hop across a mat (with sound effects). In one condition (House), the adult ended by placing the mouse in a toy house, whereas in another condition (No House) there was no house present at the final location. Infants at both ages usually simply put the mouse in the house (ignoring the hopping motion and sound effects) in the House condition, presumably because they interpreted the adult's action in terms of this final goal and so ignored the behavioral means. In contrast, infants copied the adult's action (both the hopping motion and the sound effects) when no house was present, presumably because here infants saw the action itself as the adult's only goal. From very early, infants' social learning is flexible: infants focus on and copy either the end or the means of an adult action as required by the context.
During the second year of life, infants exhibit a video deficit effect. That is, they learn significantly less from a televised demonstration than they learn from a live demonstration. We predicted that repeated exposure to televised demonstrations would increase imitation from television, thereby reducing the video deficit effect. Independent groups of 6- to 18-month-olds were exposed to live or videotaped demonstrations of target actions. Imitation of the target actions was measured 24 hours later. The video segment duration was twice that of the live presentation. Doubling exposure ameliorated the video deficit effect for 12-month-olds but not for 15- and 18-month-olds. The 6-month-olds imitated from television but did not demonstrate a video deficit effect at all, learning equally well from a live and video demonstration. Findings are discussed in terms of the perceptual impoverishment theory and the dual representation theory.
This research revealed both similarities and striking differences in early language proficiency among infants from a broad range of advantaged and disadvantaged families. English-learning infants (n = 48) were followed longitudinally from 18 to 24 months, using real-time measures of spoken language processing. The first goal was to track developmental changes in processing efficiency in relation to vocabulary learning in this diverse sample. The second goal was to examine differences in these crucial aspects of early language development in relation to family socioeconomic status (SES). The most important findings were that significant disparities in vocabulary and language processing efficiency were already evident at 18 months between infants from higher- and lower-SES families, and by 24 months there was a 6-month gap between SES groups in processing skills critical to language development.
Infants follow the gaze direction of others from the middle of the first year of life. In attempting to determine how infants understand the looking behavior of adults, a number of recent studies have blocked the adult's line of sight in some way (e.g. with a blindfold or with a barrier). In contrast, in the current studies an adult looked behind a barrier which blocked the child's line of sight. Using two different control conditions and several different barrier types, 12- and 18-month-old infants locomoted a short distance in order to gain the proper viewing angle to follow an experimenter's gaze to locations behind barriers. These results demonstrate that, contra Butterworth, even 12-month-old infants can follow gaze to locations outside of their current field of view. They also add to growing evidence that 12-month-olds have some understanding of the looking behaviors of others as an act of seeing.
A substantial body of evidence demonstrates that infants understand the meaning of spoken words from as early as 6 months. Yet little is known about their ability to do so in the absence of any visual referent, which would offer diagnostic evidence for an adult-like, symbolic interpretation of words and their use in language mediated thought. We used the head-turn preference procedure to examine whether infants can generate implicit meanings from word forms alone as early as 18 months of age, and whether they are sensitive to meaningful relationships between words. In one condition, toddlers were presented with lists of words taken from the same taxonomic category (e.g. animals or body parts). In a second condition, words taken from two other categories (e.g. clothes and food items) were interleaved within the same list. Listening times were found to be longer in the related-category condition than in the mixed-category condition, suggesting that infants extract the meaning of spoken words and are sensitive to the semantic relatedness between these words. Our results show that infants have begun to construct the rudiments of a semantic system based on taxonomic relations even before they enter a period of accelerated vocabulary growth.
Two experiments examined developmental changes in children's visual recognition of common objects during the period of 18 to 24 months. Experiment 1 examined children's ability to recognize common category instances that presented three different kinds of information: (1) richly detailed and prototypical instances that presented both local and global shape information, color, textural and featural information, (2) the same rich and prototypical shapes but no color, texture or surface featural information, or (3) that presented only abstract and global representations of object shape in terms of geometric volumes. Significant developmental differences were observed only for the abstract shape representations in terms of geometric volumes, the kind of shape representation that has been hypothesized to underlie mature object recognition. Further, these differences were strongly linked in individual children to the number of object names in their productive vocabulary. Experiment 2 replicated these results and showed further that the less advanced children's object recognition was based on the piecemeal use of individual features and parts, rather than overall shape. The results provide further evidence for significant and rapid developmental changes in object recognition during the same period children first learn object names. The implications of the results for theories of visual object recognition, the relation of object recognition to category learning, and underlying developmental processes are discussed.
Recent research indicates that toddlers and infants succeed at various non-verbal spontaneous-response false-belief tasks; here we asked whether toddlers would also succeed at verbal spontaneous-response false-belief tasks that imposed significant linguistic demands. We tested 2.5-year-olds using two novel tasks: a preferential-looking task in which children listened to a false-belief story while looking at a picture book (with matching and non-matching pictures), and a violation-of-expectation task in which children watched an adult 'Subject' answer (correctly or incorrectly) a standard false-belief question. Positive results were obtained with both tasks, despite their linguistic demands. These results (1) support the distinction between spontaneous- and elicited-response tasks by showing that toddlers succeed at verbal false-belief tasks that do not require them to answer direct questions about agents' false beliefs, (2) reinforce claims of robust continuity in early false-belief understanding as assessed by spontaneous-response tasks, and (3) provide researchers with new experimental tasks for exploring early false-belief understanding in neurotypical and autistic populations.
Language development has long been associated with motor development, particularly manual gesture. We examined a variety of motor abilities - manual gesture including symbolic, meaningless and sequential memory, oral motor control, gross and fine motor control - in 129 children aged 21 months. Language abilities were assessed and cognitive and socio-economic measures controlled for. Oral motor control was strongly associated with language production (vocabulary and sentence complexity), with some contribution from symbolic abilities. Language comprehension, however, was associated with cognitive and socio-economic measures. We conclude that symbolic, working memory, and mirror neuron accounts of language-motor control links are limited, but that a common neural and motor substrate for nonverbal and verbal oral movements may drive the motor-language association.
Using an adaptation of the Attentional Networks Test, we investigated aspects of executive control in children with chromosome 22q11.2 deletion syndrome (DS22q11.2), a common but not well understood disorder that produces non-verbal cognitive deficits and a marked incidence of psychopathology. The data revealed that children with DS22q11.2 demonstrated greater difficulty than controls in locating and processing target items in the presence of distracters. Importantly, children with DS22q11.2 showed a deficit in the ability to monitor and adapt to stimulus conflict. These data provide evidence of inadequate conflict adaptation in children with DS22q11.2, a problem that is also present in schizophrenia. The findings of specific executive dysfunction in this group may provide a linkage between particular genetic abnormalities and the development of psychopathology.
To investigate the interaction between segmental and supra-segmental stress-related information in early word learning, two experiments were conducted with 20- to 24-month-old English-learning children. In an adaptation of the object categorization study designed by Nazzi and Gopnik (2001), children were presented with pairs of novel objects whose labels differed by their initial consonant (Experiment 1) or their medial consonant (Experiment 2). Words were produced with a stress initial (trochaic) or a stress final (iambic) pattern. In both experiments successful word learning was established when the to-be-remembered contrast was embedded in a stressed syllable, but not when embedded in unstressed syllables. This was independent of the overall word pattern, trochaic or iambic, or the location of the phonemic contrast, word-initial or -medial. Results are discussed in light of the use of phonetic information in early lexical acquisition, highlighting the role of lexical stress and ambisyllabicity in early word processing.
To date, developmental research has rarely addressed the notion that imitation serves an interpersonal, socially based function. The present research thus examined the role of social engagement on 24-month-olds' imitation by manipulating the social availability of the model. In Experiment 1, the children were more likely to imitate the exact actions of a live socially responsive model compared to a videotaped model who could not provide socially contingent feedback. In Experiment 2, the children were more likely to imitate the exact actions of a model with whom they could communicate via a closed-circuit TV system than a videotaped model who could not provide interactive feedback. This research provides clear evidence that children's imitative behavior is affected by the social nature of the model. These findings are discussed in relation to theories on imitation and the video deficit.
Much of human communication and collaboration is predicated on making predictions about others' actions. Humans frequently use predictions about others' action mistakes to correct others and spare them mistakes. Such anticipatory correcting reveals a social motivation for unsolicited helping. Cognitively, it requires forward inferences about others' actions through mental attributions of goal and reality representations. The current study shows that infants spontaneously intervene when an adult is mistaken about the location of an object she is about to retrieve. Infants pointed out a correct location for an adult before she was about to commit a mistake. Infants did not intervene in control conditions when the adult had witnessed the misplacement, or when she did not intend to retrieve the misplaced object. Results suggest that preverbal infants anticipate a person's mistaken action through mental attributions of both her goal and reality representations, and correct her proactively by spontaneously providing unsolicited information.
Childers and Tomasello (2001) found that training 2 1/2-year-olds on the English transitive construction greatly improves their performance on a post-test in which they must use novel verbs in that construction. In the current study, we replicated Childers and Tomasello's finding, but using a much lower frequency of transitive verbs and models in training. We also used novel verbs that were of a different semantic class to our training verbs, demonstrating that semantic homogeneity is not crucial for generalization. We also replicated the finding that 4-year-olds are significantly more productive than 2 1/2-year-olds with the transitive construction, with the new finding that this is also true for verbs of emission. In addition, 'shared syntactic distribution' of novel verb and training verbs was found to have no observable effect on the number of 2 1/2-year-olds who were productive in the post-test.
Object recognition research is typically conducted using 2D stimuli in lieu of 3D objects. This study investigated the amount and complexity of knowledge gained from 2D stimuli in adult chimpanzees (Pan troglodytes) and young children (aged 3 and 4 years) using a titrated series of cross-dimensional search tasks. Results indicate that 3-year-old children utilize a response rule guided by local features to solve cross-dimensional tasks. Four-year-old toddlers and adult chimpanzees use information about object form and compositional structure from a 2D image to guide their search in three dimensions. Findings have specific implications to research conducted in object recognition/perception and broad relevance to all areas of research and daily living that incorporate 2D displays.
By three years of age, children are skilled at assessing under which circumstances others can see things. However, nothing is known about whether they can use this knowledge to guide their own deceptive behaviour. Here we investigated 3-year-olds' ability to strategically inhibit or conceal forbidden actions that a nearby adult experimenter could see or hear. In the first experiment, children were more likely to disobey the adult when she did not have visual access to their activities than they were when she was looking at them. In the second experiment, in which the adult could never see the child, children refrained from making noise when engaging in a prohibited action that the adult might hear. These results suggest that by three years of age children use their knowledge of others' perceptual states to decide whether it is safe to commit a transgression and, moreover, actively conceal perceptual cues that could reveal to others their ongoing transgression.
Inhibitory control (IC) is a dimension of child temperament that involves the self-regulation of behavioral responses under some form of instruction or expectation. Although IC is posited to appear in toddlerhood, the voluntary control of emotions such as anger begins earlier. Little research has analyzed relations between emotional development in infancy and later emerging IC. We examined phenotypic associations and genetic and environmental influences on parent- and laboratory-assessed anger and IC in a twin sample from 12 to 36 months of age. Typically, twins with low levels of IC had high levels of anger. Behavioral genetic findings confirmed significant genetic influences on anger and IC as assessed by parents, and on lab-based anger assessments. Shared environmental factors contributed to twin similarity on lab-assessed anger and IC at 36 months. Phenotypic covariance between anger and IC was largely due to overlapping genetic factors for parent ratings, and environmental factors in the laboratory.
The brain is highly sensitive to environmental hypoxia. Little is known, however, about the neuropsychological effects of high altitude residence in the developing brain. We recently described only minor changes in processing speed in native Bolivian children and adolescents living at approximately 3700 m. However, evidence for loss of cerebral autoregulation above this altitude (4000 m) suggests a potential threshold of hypoxia severity over which neuropsychological functioning may be compromised. We conducted physiological and neuropsychological assessments in 62 Bolivian children and adolescents living at La Paz (∼3700 m) and El Alto (∼4100 m) in order to address this issue. Groups were equivalent in terms of age, gender, social class, schooling, parental education and genetic admixture. Apart from percentage of hemoglobin saturated with oxygen in arterial blood (%SpO(2)), participants did not differ in their basal cardiac and cerebrovascular performance as explored by heart rate, mean arterial pressure, end-tidal carbon dioxide, and cerebral blood flow velocity at the basilar, anterior, middle and posterior cerebral arteries. A comprehensive neuropsychological assessment was administered, including tests of executive functions, attention, memory and psychomotor performance. Participants living at extreme altitude showed lower levels of performance in all executive tests (Cohen effect size = -0.91), whereas all other domains remained unaffected by altitude of residence. These results are compatible with earlier physiological evidence of a transitional zone for cerebral autoregulation at an altitude of 4000 m. We now show that above this threshold, the developing brain is apparently increasingly vulnerable to neuropsychological deficit.
Socioeconomic status (SES) is associated with childhood cognitive achievement. In previous research we found that this association shows neural specificity; specifically we found that groups of low and middle SES children differed disproportionately in perisylvian/language and prefrontal/executive abilities relative to other neurocognitive abilities. Here we address several new questions: To what extent does this disparity between groups reflect a gradient of SES-related individual differences in neurocognitive development, as opposed to a more categorical difference? What other neurocognitive systems differ across individuals as a function of SES? Does linguistic ability mediate SES differences in other systems? And how do specific prefrontal/executive subsystems vary with SES? One hundred and fifty healthy, socioeconomically diverse first-graders were administered tasks tapping language, visuospatial skills, memory, working memory, cognitive control, and reward processing. SES explained over 30% of the variance in language, and a smaller but highly significant portion of the variance in most other systems. Statistically mediating factors and possible interventional approaches are discussed.
The present study was aimed at exploring newborns' ability to recognize configural changes within real face images by testing newborns' sensitivity to the Thatcher illusion. Using the habituation procedure, newborns' ability to discriminate between an unaltered face image and the same face with the eyes and the mouth 180 degrees rotated (i.e. thatcherized) was investigated. Newborns were able to discriminate an unaltered from the thatcherized version of the same face when stimuli were presented in the canonical upright orientation (Experiment 1), but failed to discriminate the same stimuli when they were presented upside-down (Experiment 2). The results indicate that sensitivity to fine spatial information (defined as second-order relational information) in processing upright faces is already present at birth.
Tracing the connections from brain functions to children's cognitive development and education is a major goal of modern neuroscience. We performed the first meta-analysis of functional magnetic resonance imaging (fMRI) data obtained over the past decade (1999-2008) on more than 800 children and adolescents in three core systems of cognitive development and school learning: numerical abilities, reading, and executive functions (i.e. cognitive control). We ran Activation Likelihood Estimation (ALE) meta-analyses to obtain regions of reliable activity across all the studies. The results indicate that, unlike results usually reported for adults, children primarily engage the frontal cortex when solving numerical tasks. With age, there may be a shift from reliance on the frontal cortex to reliance on the parietal cortex. In contrast, the frontal, temporo-parietal and occipito-temporal regions at work during reading in children are very similar to those reported in adults. The executive frontal regions are also consistent with the imaging literature on cognitive control in adults, but the developmental comparison between children and adolescents demonstrates a key role of the anterior insular cortex (AIC) with an additional right AIC involvement in adolescents.
Although child maltreatment has often been described as leading to language deficits, the few well-controlled investigations of language acquisition in maltreated children have focused on language content rather than form, or have used qualitative rather than quantitative measures. This study examines syntactic complexity in 19 maltreated and 14 nonmaltreated preschool-aged children. Mother-child dyads participated in play sessions that were transcribed and scored for the presence of morphosyntactic forms in child speech and for specific sentence constructions in maternal speech. Findings indicated that child maltreatment was associated with language delay in both vocabulary and production of syntactic structures. There were also qualitative differences in characteristics of maternal utterances between maltreating and comparison groups. Because maltreatment initially occurred before age 2, this study highlights the long-lasting negative influence of maltreatment on language development and also provides the first demonstration of child language delays and differences in maternal speech within a single maltreatment sample.
When preschoolers overcome persistent error, subsequent patterns of correct choices may identify how the error had been overcome. Children who no longer misrepresented a ball rolling down a bent tube as though it could only fall vertically, were asked sometimes to approach and sometimes to avoid where the ball landed. All children showed requisite task-switching flexibility. The pattern of 4-year-olds' correct choices among different places showed unnecessary avoidance of any place that would previously have tempted them into a vertical-approach error, 5-year-olds rebounded into a reversal, and 7-year-olds were flexible. The data attest to an inhibition mechanism, ruling out competing possibilities.
Previous research shows a correlation between individual differences in people's school math abilities and the accuracy with which they rapidly and nonverbally approximate how many items are in a scene. This finding is surprising because the Approximate Number System (ANS) underlying numerical estimation is shared with infants and with non-human animals who never acquire formal mathematics. However, it remains unclear whether the link between individual differences in math ability and the ANS depends on formal mathematics instruction. Earlier studies demonstrating this link tested participants only after they had received many years of mathematics education, or assessed participants' ANS acuity using tasks that required additional symbolic or arithmetic processing similar to that required in standardized math tests. To ask whether the ANS and math ability are linked early in life, we measured the ANS acuity of 200 3- to 5-year-old children using a task that did not also require symbol use or arithmetic calculation. We also measured children's math ability and vocabulary size prior to the onset of formal math instruction. We found that children's ANS acuity correlated with their math ability, even when age and verbal skills were controlled for. These findings provide evidence for a relationship between the primitive sense of number and math ability starting early in life.
A fundamental assumption of the causal graphical model framework is the Markov assumption, which posits that learners can discriminate between two events that are dependent because of a direct causal relation between them and two events that are independent conditional on the value of another event(s). Sobel and Kirkham (2006) demonstrated that 8-month-old infants registered conditional independence information among a sequence of events; infants responded according to the Markov assumption
in such a way that was inconsistent with models that rely on simple calculations of associative strength. The present experiment extends these findings to younger infants, and demonstrates that such responses potentially develop during the second half of the first year of life. These data are discussed in terms of a developmental trajectory between associative mechanisms and causal graphical models as representations of infants’ causal and statistical learning.
This study considered how far nonverbal cognitive, language and reading abilities are affected by common genetic influences in a sample of 312 typically developing Chinese twin pairs aged from 3 to 11 years. Children were individually given tasks of Chinese word reading, receptive vocabulary, phonological memory, tone awareness, syllable and rhyme awareness, rapid automatized naming, morphological awareness and orthographic skills, and Raven's Colored Progressive Matrices. Factor analyses on the verbal tasks adjusted for age indicated two factors: Language as the first factor and Reading as the second factor. Univariate genetic analyses indicated that genetic influences were substantial for nonverbal cognitive ability and moderate for language and reading. Multivariate genetic analyses showed that nonverbal cognitive ability, language and reading were influenced by shared genetic origins, although there were specific genetic influences on verbal skills that were distinct from those on nonverbal cognitive ability. This study extends the Generalist Genes Hypothesis to Chinese language and reading skills, suggesting that the general effects of genes could be universal across languages.
Spatial ability predicts performance in mathematics and eventual expertise in science, technology and engineering. Spatial skills have also been shown to rely on neuronal networks partially shared with mathematics. Understanding the nature of this association can inform educational practices and intervention for mathematical underperformance. Using data on two aspects of spatial ability and three domains of mathematical ability from 4174 pairs of 12-year-old twins, we examined the relative genetic and environmental contributions to variation in spatial ability and to its relationship with different aspects of mathematics. Environmental effects explained most of the variation in spatial ability (~70%) and in mathematical ability (~60%) at this age, and the effects were the same for boys and girls. Genetic factors explained about 60% of the observed relationship between spatial ability and mathematics, with a substantial portion of the relationship explained by common environmental influences (26% and 14% by shared and non-shared environments respectively). These findings call for further research aimed at identifying specific environmental mediators of the spatial-mathematics relationship.
About a third of the variation in spatial ability at age 12 is explained by genetic factors; a little less than half of the variation in mathematics at this age is genetic. We find no sex differences in the genetic and environmental influences (either in magnitude or type) on mathematical and spatial variation at age 12. The observed overlap between spatial ability and mathematics is substantial (r > .40). Approximately 60% of this overlap is explained by common genetic effects, with 40% of the overlap due to environmental experience.
A connectionist model of causal attribution is presented, emphasizing the use of domain-general principles of processing and learning previously employed in models of semantic cognition. The model categorizes objects dependent upon their observed 'causal properties' and is capable of making several types of inferences that 4-year-old children have been shown to be capable of. The model gives rise to approximate conformity to normative models of causal inference and gives approximate estimates of the probability that an object presented in an ambiguous situation actually possesses a particular causal power, based on background knowledge and recent observations. It accounts for data from three sets of experimental studies of the causal inferencing abilities of young children. The model provides a base for further efforts to delineate the intuitive mechanisms of causal inference employed by children and adults, without appealing to inherent principles or mechanisms specialized for causal as opposed to other forms of reasoning.
Three experiments investigated whether children in grades K, 2, and 4 (n = 144) view emotional comprehension as important in solving moral dilemmas. The experiments asked whether a human or an artificially intelligent machine would be best at solving different types of problems, ranging from moral and emotional to nonmoral and pragmatic. In Experiment 1, children in all age groups indicated that a human would be superior to a computer not only at comprehending emotions, but also at solving moral dilemmas. In Experiment 2, older children also indicated that a human could solve moral dilemmas better than a 'robot' with human-like perceptual and physical abilities. Experiment 3 further demonstrated that these effects were not solely due to a bias towards humans. Thus, children as young as age 5 view emotional understanding as an important element for moral, but not for nonmoral, reasoning, suggesting that the basis for Humean intuitions emerges early in life.
Various studies have shown that infants in their first year of life are able to interpret human actions as goal-directed. It is argued that this understanding is a precondition for understanding intentional actions and attributing mental states. Moreover, some authors claim that this early action understanding is a precursor of later Theory of Mind (ToM) development. To test this, we related 6-month-olds' performance in an action interpretation task to their performance in ToM tasks at the age of 4 years. Action understanding was assessed using a modified version of the Woodward-paradigm (Woodward, 1999). At the age of 4 years, the same children were tested with the German version of the ToM scale developed by Wellman and Liu (2004). Results revealed a correlation between infants' decrement of attention to goal-directed action and their ability to solve a false belief task at the age of 4 years with no modulation by language abilities. Our results indicate a link between infant attention to goal-directed action and later theory of mind abilities.
The etiology of individual differences in general verbal ability, verbal learning and letter and category fluency were examined in two independent samples of 9- and 18-year-old twin pairs and their siblings. In both age groups, we observed strong familial resemblance for general verbal ability and moderate familial resemblance for verbal learning, letter and category fluency. All familial resemblance was explained by genetic factors. There was significant covariance among the tests, which was stronger in magnitude in the adolescent cohort. The covariance was mainly explained by genetic effects shared by subtests, both in middle childhood and in late adolescence. In addition to a shared set of genes that influenced all phenotypes, there were also genetic influences specific to the different verbal phenotypes.
This paper investigates the ability of infants to attend to continuous stimulus variables and how this capacity relates to the representation of number. We examined the change in area needed by 6-month-old infants to detect a difference in the size of a single element (Elmo face). Infants successfully discriminated a 1:4, 1:3 and 1:2 change in the area of the Elmo face but failed to discriminate a 2:3 change. In addition, the novelty preference was linearly related to the ratio difference between the novel and familiar area. Results suggest that Weber's Law holds for area discriminations in infancy and also reveal that at 6 months of age infants are equally sensitive to number, time and area.
Bronchopulmonary dysplasia is the most common pulmonary morbidity in preterm infants and is associated with chronic hypoxia. Animal studies have demonstrated structural, neurochemical and functional alterations due to chronic hypoxia in the developing brain. Long-term impairments in visual-motor, gross and fine motor, articulation, reading, mathematics, spatial memory and attention skills are prevalent in survivors of bronchopulmonary dysplasia, and impairments appear to correlate with the severity of hypoxia. However, due to the simultaneous occurrence of multiple neurodevelopmental risk factors, a primary or potentiating role for chronic hypoxia in these impairments has yet to be conclusively established.
We explored whether rhesus monkeys (Macaca mulatta) share one important feature of human essentialist reasoning: the capacity to track category membership across radical featural transformations. Specifically, we examined whether monkeys--like children (Keil, 1989)--expect a transformed object to have the internal properties of its original category. In two experiments, monkeys watched as an experimenter visually transformed a familiar fruit (e.g. apple) into a new kind of fruit (e.g. coconut) either by placing a fruit exterior over the original, or by removing an exterior shell and revealing the inside kind of fruit. The experimenter then pretended to place an inside piece of the transformed fruit into a box which the monkey was allowed to search. Results indicated that monkeys searched the box longer when they found a piece of fruit inconsistent with the inside kind, suggesting that the monkeys expected that the inside of the transformed fruit would taste like the innermost kind they saw. These results suggest that monkeys may share at least one aspect of psychological essentialism: they maintain category-specific expectations about an object's internal properties even when that object's external properties change. These results therefore suggest that some essentialist expectations may emerge in the absence of language, and thus raise the possibility that such tendencies may emerge earlier in human development than has previously been considered.
The present research investigated the nature of the inferences and decisions young children make about informants with a prior history of inaccuracies. Across three experiments, 3- and 4-year-olds (total N = 182) reacted to previously inaccurate informants who offered testimony in an object-labeling task. Of central interest was children's willingness to accept information provided by an inaccurate informant in different contexts of being alone, paired with an accurate informant, or paired with a novel (neutral) informant. Experiments 1 and 2 showed that when a previously inaccurate informant was alone and provided testimony that was not in conflict with the testimony of another informant, children systematically accepted the testimony of that informant. Experiment 3 showed that children accepted testimony from a neutral informant over an inaccurate informant when both provided information, but accepted testimony from an inaccurate informant rather than seeking information from an available neutral informant who did not automatically offer information. These results suggest that even though young children use prior history of accuracy to determine the relative reliability of informants, they are quite willing to trust the testimony of a single informant alone, regardless of whether that informant had previously been reliable.
In this study we examined the relationship between menarche and interest in infants among adolescent girls, and the effects of early environment, particularly of father absence from home, on both variables. Eighty-three girls ranging in age from between 11 and 14 years served as study participants. Interest in infants was assessed through their preferences for photos and silhouettes of animal and human faces of infants versus adults. Information on menarche and the early family environment was obtained with questionnaires and interviews. Variation in menarcheal status or timing of menarche was associated with some differences in interest in infants. There was little or no evidence, however, that suggested a direct causal relationship between these variables. Instead, both menarche and interest in infants were independently associated with early father absence from home such that father-absent girls exhibited earlier menarche and greater attraction to infant visual stimuli than father-present girls. Our results are consistent with the hypothesis that father absence is associated with a developmental trajectory characterized by earlier readiness for reproduction and parenting.
There is currently controversy over the nature of 1-year-olds' social-cognitive understanding and motives. In this study we investigated whether 12-month-old infants point for others with an understanding of their knowledge states and with a prosocial motive for sharing experiences with them. Declarative pointing was elicited in four conditions created by crossing two factors: an adult partner (1) was already attending to the target event or not, and (2) emoted positively or neutrally. Pointing was also coded after the event had ceased. The findings suggest that 12-month-olds point to inform others of events they do not know about, that they point to share an attitude about mutually attended events others already know about, and that they can point (already prelinguistically) to absent referents. These findings provide strong support for a mentalistic and prosocial interpretation of infants' prelinguistic communication.
Sequences of notes contain several different types of pitch cues, including both absolute and relative pitch information. What factors determine which of these cues are used when learning about tone sequences? Previous research suggests that infants tend to preferentially process absolute pitch patterns in continuous tone sequences, while other types of input elicit relative pitch use by infants. In order to ask whether the structure of the input influences infants' choice of pitch cues, we presented learners with continuous tone streams in which absolute pitch cues were rendered uninformative by transposing the tone sequences. Under these circumstances, both infants and adults successfully tracked relative pitches in a statistical learning task. Implications for the role played by the structure of the input in the learning process are considered.
By 7 months of age, infants are able to learn rules based on the abstract relationships between stimuli (Marcus et al., 1999), but they are better able to do so when exposed to speech than to some other classes of stimuli. In the current experiments we ask whether multimodal stimulus information will aid younger infants in identifying abstract rules. We habituated 5-month-olds to simple abstract patterns (ABA or ABB) instantiated in coordinated looming visual shapes and speech sounds (Experiment 1), shapes alone (Experiment 2), and speech sounds accompanied by uninformative but coordinated shapes (Experiment 3). Infants showed evidence of rule learning only in the presence of the informative multimodal cues. We hypothesize that the additional evidence present in these multimodal displays was responsible for the success of younger infants in learning rules, congruent with both a Bayesian account and with the Intersensory Redundancy Hypothesis.
Why do people perseverate, repeating prior behaviours that are no longer appropriate? Many accounts point to isolated deficits in processes such as inhibition or attention. We instead posit a fundamental difference in rule representations: flexible switchers use active representations that rely on later-developing prefrontal cortical areas and are more abstract, whereas perseverators use latent representations that rely on earlier-developing posterior cortical and subcortical areas and are more stimulus-specific. Thus, although switchers and perseverators should apply the rules they use to familiar stimuli equally reliably, perseverators should show unique limitations in generalizing their rules to novel stimuli, a process that requires abstract representations. Two behavioural experiments confirmed this counterintuitive prediction early in development. Three-year-old children sorted cards by one rule, were asked to switch to another rule, and then were asked simply to continue their behaviour, with novel cards. Perseverators applied the rule they were using (the first rule) just as reliably as switchers applied the rule they were using (the second rule) with familiar cards; however, only switchers generalized their rule to novel cards. This finding supports an early link between active representations that support switching and abstract representations that support generalization. We interpret this synergy in terms of prefrontal cortical development.