Showing papers in "Developmental Science in 2007"

Socioeconomic Gradients Predict Individual Differences in Neurocognitive Abilities.

Abstract: 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.

'Like me': a foundation for social cognition.

Abstract: Infants represent the acts of others and their own acts in commensurate terms. They can recognize cross-modal equivalences between acts they see others perform and their own felt bodily movements. This recognition of self‐other equivalences in action gives rise to interpreting others as having similar psychological states such as perceptions and emotions. The ‘like me’ nature of others is the starting point for social cognition, not its culmination.

Is speech learning ‘gated’ by the social brain?

Abstract: I advance the hypothesis that the earliest phases of language acquisition ‐ the developmental transition from an initial universal state of language processing to one that is language-specific ‐ requires social interaction. Relating human language learning to a broader set of neurobiological cases of communicative development, I argue that the social brain ‘gates’ the computational mechanisms involved in human language learning.

Risk-taking and the adolescent brain: who is at risk?

Abstract: Relative to other ages, adolescence is described as a period of increased impulsive and risk-taking behavior that can lead to fatal outcomes (suicide, substance abuse, HIV, accidents, etc.). This study was designed to examine neural correlates of risk-taking behavior in adolescents, relative to children and adults, in order to predict who may be at greatest risk. Activity in reward-related neural circuitry in anticipation of a large monetary reward was measured with functional magnetic resonance imaging, and anonymous self-report ratings of risky behavior, anticipation of risk and impulsivity were acquired in individuals between the ages of 7 and 29 years. There was a positive association between accumbens activity and the likelihood of engaging in risky behavior across development. This activity also varied as a function of individuals' ratings of anticipated positive or negative consequences of such behavior. Impulsivity ratings were not associated with accumbens activity, but rather with age. These findings suggest that during adolescence, some individuals may be especially prone to engage in risky behaviors due to developmental changes in concert with variability in a given individual's predisposition to engage in risky behavior, rather than to simple changes in impulsivity.

What's in a look?

Abstract: The most common behavioral technique used to study infant perception, cognition, language, and social development is some variant of looking time. Since its inception as a reliable method in the late 1950s, a tremendous increase in knowledge about infant competencies has been gained by inferences made from measures of looking time. Here we examine the logic, utility, and future prospects for further gains in our understanding of infant cognition from the use of looking time measures.

What Did Simon Say? Revisiting the Bilingual Advantage.

Abstract: Bilingual children often outperform monolingual children in tasks of cognitive control. This advantage may be a consequence of the fact that bilinguals have more practice controlling attention due to an ongoing need to manage two languages. However, existing evidence is limited because possible differences in ethnicity and socioeconomic status have not been properly controlled. To address this issue, we administered the Simon task to bilingual and monolingual children of identical ethnic and socioeconomic backgrounds. Bilingual and monolingual children performed identically, whereas children from higher SES families were advantaged relative to children from lower SES families. Controlling differences in SES and ethnicity may attenuate the bilingual advantage in cognitive control.

Learning overhypotheses with hierarchical Bayesian models

Abstract: Inductive learning is impossible without overhypotheses, or constraints on the hypotheses considered by the learner. Some of these overhypotheses must be innate, but we suggest that hierarchical Bayesian models can help to explain how the rest are acquired. To illustrate this claim, we develop models that acquire two kinds of overhypotheses--overhypotheses about feature variability (e.g. the shape bias in word learning) and overhypotheses about the grouping of categories into ontological kinds like objects and substances.

Listening to Language at Birth: Evidence for a Bias for Speech in Neonates.

Abstract: The nature and origin of the human capacity for acquiring language is not yet fully understood. Here we uncover early roots of this capacity by demonstrating that humans are born with a preference for listening to speech. Human neonates adjusted their high amplitude sucking to preferentially listen to speech, compared with complex non-speech analogues that controlled for critical spectral and temporal parameters of speech. These results support the hypothesis that human infants begin language acquisition with a bias for listening to speech. The implications of these results for language and communication development are discussed. For a commentary on this article see Rosen and Iverson (2007).

Development of emotional facial recognition in late childhood and adolescence

Abstract: The ability to interpret emotions in facial expressions is crucial for social functioning across the lifespan. Facial expression recognition develops rapidly during infancy and improves with age during the preschool years. However, the developmental trajectory from late childhood to adulthood is less clear. We tested older children, adolescents and adults on a two-alternative forced-choice discrimination task using morphed faces that varied in emotional content. Actors appeared to pose expressions that changed incrementally along three progressions: neutral-to-fear, neutral-to-anger, and fear-to-anger. Across all three morph types, adults displayed more sensitivity to subtle changes in emotional expression than children and adolescents. Fear morphs and fear-to-anger blends showed a linear developmental trajectory, whereas anger morphs showed a quadratic trend, increasing sharply from adolescents to adults. The results provide evidence for late developmental changes in emotional expression recognition with some specificity in the time course for distinct emotions.

Visual category-selectivity for faces, places and objects emerges along different developmental trajectories.

Abstract: The organization of category-selective regions in ventral visual cortex is well characterized in human adults. We investigated a crucial, previously unaddressed, question about how this organization emerges developmentally. We contrasted the developmental trajectories for face-, object-, and place-selective activation in the ventral visual cortex in children, adolescents, and adults. Although children demonstrated adult-like organization in object- and place-related cortex, as a group they failed to show consistent face-selective activation in classical face regions. The lack of a consistent neural signature for faces was attributable to (1) reduced face-selectivity and extent of activation within the regions that will become the FFA, OFA, and STS in adults, and (2) smaller volumes and considerable variability in the locus of face-selective activation in individual children. In contrast, adolescents showed an adult-like pattern of face-selective activation, although it was more right-lateralized. These findings reveal critical age-related differences in the emergence of category-specific functional organization in the visual cortex and support a model of brain development in which specialization emerges from interactions between experience-dependent learning and the maturing brain.

Religion is natural

Abstract: Despite its considerable intellectual interest and great social relevance, religion has been neglected by contemporary developmental psychologists. But in the last few years, there has been an emerging body of research exploring children's grasp of certain universal religious ideas. Some recent findings suggest that two foundational aspects of religious belief – belief in mind–body dualism, and belief in divine agents – come naturally to young children. This research is briefly reviewed, and some future directions are discussed.

Enculturated chimpanzees imitate rationally

Abstract: Human infants imitate others’ actions ‘rationally’: they copy a demonstrator's action when that action is freely chosen, but less when it is forced by some constraint (Gergely, Bekkering & Kiraly, 2002) We investigated whether enculturated chimpanzees (Pan troglodytes) also imitate rationally Using Gergely and colleagues’ (2002) basic procedure, a human demonstrator operated each of six apparatuses using an unusual body part (he pressed it with his forehead or foot, or sat on it) In the Hands Free condition he used this unusual means even though his hands were free, suggesting a free choice In the Hands Occupied condition he used the unusual means only because his hands were occupied, suggesting a constrained or forced choice Like human infants, chimpanzees imitated the modeled action more often in the Hands Free than in the Hands Occupied condition Enculturated chimpanzees thus have some understanding of the rationality of others’ intentional actions, and use this understanding when imitating others

Gene–environment interdependence

Abstract: Behavioural genetics was initially concerned with partitioning population variance into that due to genetics and that due to environmental influences. The implication was that the two were separate and it was assumed that gene–environment interactions were usually of so little importance that they could safely be ignored. Theoretical considerations suggested that that was unlikely to be true and empirical findings are now accumulating on the demonstrated and replicated biological interactions between identified common single genetic variants and the operation of environmentally mediated risks. The paper outlines the evidence and considers why it is changing concepts in ways that matter.

The mirror neuron system: grasping others’ actions from birth?

Abstract: In the adult human brain, the presence of a system matching the observation and the execution of actions is well established. This mechanism is thought to rely primarily on the contribution of so-called ‘mirror neurons’, cells that are active when a specific gesture is executed as well as when it is seen or heard. Despite the wealth of evidence detailing the existence of a mirror neuron system (MNS) in the adult brain, little is known about its normal development. Yet, a better understanding of the MNS in infants would be of considerable theoretical and clinical interest, as dysfunctions within the MNS have been demonstrated in neurodevelopmental disorders such as autism spectrum disorder. Arguments in favor of an innate, or very early, mechanism underlying action understanding mainly come from studies of neonatal imitation, the existence of which has been questioned by some. Here, we review evidence suggesting the presence of an MNS in the human child, as well as work that suggests, although indirectly, the existence of a mechanism matching the perception and the execution of actions in the human newborn.

Young children use their hands to tell their mothers what to say.

Abstract: Children produce their first gestures before their first words, and their first gesture + word sentences before their first word + word sentences. These gestural accomplishments have been found not only to predate linguistic milestones, but also to predict them. Findings of this sort suggest that gesture itself might be playing a role in the language-learning process. But what role does it play? Children’s gestures could elicit from their mothers the kinds of words and sentences that the children need to hear in order to take their next linguistic step. We examined maternal responses to the gestures and speech that 10 children produced during the one-word period. We found that all 10 mothers ‘translated’ their children’s gestures into words, providing timely models for how one- and two-word ideas can be expressed in English. Gesture thus offers a mechanism by which children can point out their thoughts to mothers, who then calibrate their speech to those thoughts, and potentially facilitate language-learning.

Infants' perception of goal-directed actions: development through cue-based bootstrapping.

Abstract: It is now widely accepted that sensitivity to goal-directed actions emerges during the first year of life. However, controversy still surrounds the question of how this sensitivity emerges and develops. One set of views emphasizes the role of observing behavioral cues, while another emphasizes the role of experience with producing own action. In a series of four experiments we contrast these two views. In Experiment 1, it was shown that infants as young as 6 months old can interpret an unfamiliar human action as goal-directed when the action involves equifinal variations. Experiments 2 and 3 demonstrated that 12- and 9-month-olds are also able to attribute goals to an inanimate action if it displays behavioral cues such as self-propelledness and an action-effect. In Experiment 4, we found that even 6-months-olds can encode the goal object of an inanimate action if all three cues, equifinality, self-propelledness and an action-effect, were present. These findings suggest that the ability to ascribe goal-directedness does not necessarily emerge from hands-on experience with particular actions and that it is independent from the specific appearance of the actor as long as sufficient behavioral cues are available. We propose a cue-based bootstrapping model in which an initial sensitivity to behavioral cues leads to learning about further cues. The further cues in turn inform about different kinds of goal-directed agents and about different types of actions. By uniting an innate base with a learning process, cue-based bootstrapping can help reconcile divergent views on the emergence of infants' ability to understand actions as goal-directed.

Development of action monitoring through adolescence into adulthood: ERP and source localization

Abstract: In this study we examined the development of three action monitoring event-related potentials (ERPs) - the error-related negativity (ERN/Ne), error positivity (P(E)) and the N2 - and estimated their neural sources. These ERPs were recorded during a flanker task in the following groups: early adolescents (mean age = 12 years), late adolescents (mean age = 16 years), and adults (mean age = 29 years). The amplitudes of the ERN/Ne and N2 were greater in the adult and late adolescent groups than in the early adolescent group. Both of these components had neural sources in the anterior cingulate cortex (ACC). Although P(E) was present across groups, P(E) amplitude was greater in the late adolescent group compared to the adult group and also had neural sources in the ACC. ERN/Ne amplitude was related to post-error slowing across age groups; it was related to task performance only in the adult group. These findings are discussed in light of the role of the maturation of the ACC in the development of action monitoring processes.

Preschool children learn about causal structure from conditional interventions.

Abstract: The conditional intervention principle is a formal principle that relates patterns of interventions and outcomes to causal structure. It is a central assumption of experimental design and the causal Bayes net formalism. Two studies suggest that preschoolers can use the conditional intervention principle to distinguish causal chains, common cause and interactive causal structures even in the absence of differential spatiotemporal cues and specific mechanism knowledge. Children were also able to use knowledge of causal structure to predict the patterns of evidence that would result from interventions. A third study suggests that children's spontaneous play can generate evidence that would support such accurate causal learning.

Action in development.

Abstract: It is argued that cognitive development has to be understood in the functional perspective provided by actions. Actions reflect all aspects of cognitive development including the motives of the child, the problems to be solved, and the constraints and possibilities of the child's body and sensorimotor system. Actions are directed into the future and their control is based on knowledge of what is going to happen next. Such knowledge is available because events are governed by rules and regularities. The planning of actions also requires knowledge of the affordances of objects and events. An important aspect of cognitive development is about how the child acquires such knowledge.

Sensitivity to sampling in Bayesian word learning.

Abstract: We report a new study testing our proposal that word learning may be best explained as an approximate form of Bayesian inference (Xu & Tenenbaum, in press). Children are capable of learning word meanings across a wide range of communicative contexts. In different contexts, learners may encounter different sampling processes generating the examples of word-object pairings they observe. An ideal Bayesian word learner could take into account these differences in the sampling process and adjust his/her inferences about word meaning accordingly. We tested how children and adults learned words for novel object kinds in two sampling contexts, in which the objects to be labeled were sampled either by a knowledgeable teacher or by the learners themselves. Both adults and children generalized more conservatively in the former context; that is, they restricted the label to just those objects most similar to the labeled examples when the exemplars were chosen by a knowledgeable teacher, but not when chosen by the learners themselves. We discuss how this result follows naturally from a Bayesian analysis, but not from other statistical approaches such as associative word-learning models.

Temporal discrimination increases in precision over development and parallels the development of numerosity discrimination

Abstract: Time perception is important for many aspects of human behavior, and a large literature documents that adults represent intervals and that their ability to discriminate temporal intervals is ratio dependent. Here we replicate a recent study by vanMarle and Wynn (2006) that used the visual habituation paradigm and demonstrated that temporal discrimination in 6-month-old infants is also ratio dependent. We further demonstrate that between 6 and 10 months of age temporal discrimination increases in precision such that by 10 months of age infants succeed at discriminating a 2:3 ratio, a ratio that 6-month-old infants were unable to discriminate. We discuss the potential implications of the fact that temporal discrimination follows the same developmental progression that has been previously observed for number discrimination in infancy (Lipton & Spelke, 2003).

Age-related changes in deferred imitation from television by 6- to 18-month-olds.

Abstract: 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.

Pointing out new news, old news, and absent referents at 12 months of age.

Abstract: 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.

Now I see it but you don't: 14-month-olds can represent another person's visual perspective.

Abstract: 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.

Fourteen-month-olds know what others experience only in joint engagement

Abstract: We investigated how 14-month-old infants know what others know. In two studies, an infant played with each of two objects in turn while an experimenter was present. Then the experimenter left the room, and the infant played with a third object with an assistant. The experimenter returned, faced all three objects, and said excitedly ‘Look! Can you give it to me?’ In Study 1, the experimenter experienced each of the first two toys in episodes of joint visual engagement (without manipulation) with the infant. In response to her excited request infants gave the experimenter the object she did not know, thus demonstrating that they knew which ones she knew. In Study 2, infants witnessed the experimenter jointly engage around each of the experienced toys with the assistant, from a third-person perspective. In response to her request, infants did not give the experimenter the object she had not experienced. In combination with other studies, these results suggest that to know what others have experienced 14-month-old infants must do more than just perceive others perceiving something; they must engage with them actively in joint engagement.

Decision-making in healthy children, adolescents and adults explained by the use of increasingly complex proportional reasoning rules.

Abstract: In the standard Iowa Gambling Task (IGT), participants have to choose repeatedly from four options. Each option is characterized by a constant gain, and by the frequency and amount of a probabilistic loss. Crone and van der Molen (2004) reported that school-aged children and even adolescents show marked deficits in IGT performance. In this study, we have re-analyzed the data with a multivariate normal mixture analysis to show that these developmental changes can be explained by a shift from unidimensional to multidimensional proportional reasoning (Siegler, 1981; Jansen & van der Maas, 2002). More specifically, the results show a gradual shift with increasing age from (a) guessing with a slight tendency to consider frequency of loss to (b) focusing on frequency of loss, to (c) considering both frequency and amount of probabilistic loss. In the latter case, participants only considered options with low-frequency loss and then chose the option with the lowest amount of loss. Performance improved in a reversed task, in which punishment was placed up front and gain was delivered unexpectedly. In this reversed task, young children are guessing with already a slight tendency to consider both the frequency and amount of gain; this strategy becomes more pronounced with age. We argue that these findings have important implications for the interpretation of IGT performance, as well as for methods to analyze this performance.

Bayesian networks, Bayesian learning and cognitive development.

Abstract: Over the past 30 years we have discovered an enormous amount about what children know and when they know it. But the real question for developmental cognitive science is not so much what children know, when they know it or even whether they learn it. The real question is how they learn it and why they get it right. Developmental ‘theory theorists’ (e.g. Carey, 1985; Gopnik & Meltzoff, 1997; Wellman & Gelman, 1998) have suggested that children’s learning mechanisms are analogous to scientific theory-formation. However, what we really need is a more precise computational specification of the mechanisms that underlie both types of learning, in cognitive development and scientific discovery. The most familiar candidates for learning mechanisms in developmental psychology have been variants of associationism, either the mechanisms of classical and operant conditioning in behaviorist theories (e.g. Rescorla & Wagner, 1972) or more recently, connectionist models (e.g. Rumelhart & McClelland, 1986; Elman, Bates, Johnson & Karmiloff-Smith, 1996; Shultz, 2003; Rogers & McClelland, 2004). Such theories have had difficulty explaining how apparently rich, complex, abstract, rulegoverned representations, such as we see in everyday theories, could be derived from evidence. Typically, associationists have argued that such abstract representations do not really exist, and that children’s behavior can be just as well explained in terms of more specific learned associations between task inputs and outputs. Connectionists often qualify this denial by appealing to the notion of distributed representations in hidden layers of units that relate inputs to outputs (Rogers & McClelland, 2004; Colunga & Smith, 2005). On this view, however, the representations are not explicit, task-independent models of the world’s structure that are responsible for the input–output relations. Instead, they are implicit summaries of the input–output relations for a specific set of tasks that the connectionist network has been trained to perform. Conversely, more nativist accounts of cognitive development endorse the existence of abstract rule-governed representations but deny that their basic structure is learned. Modularity or ‘core knowledge’ theorists, for example, suggest that there are a small number of innate causal schemas designed to fit particular domains of knowledge, such as a belief-desire schema for intuitive psychology or a generic object schema for intuitive physics. Development is either a matter of enriching those innate schemas, or else involves quite sophisticated and culturespecific kinds of learning like those of the social institutions of science (e.g. Spelke, Breinlinger, Macomber & Jacobson, 1992). This has left empirically minded developmentalists, who seem to see both abstract representation and learning in even the youngest children, in an unfortunate theoretical bind. There appears to be a vast gap between the kinds of knowledge that children learn and the mechanisms that could allow them to learn that knowledge. The attempt to bridge this gap dates back to Piagetian ideas about constructivism, of course, but simply saying that there are constructivist learning mechanisms is a way of restating the problem rather than providing a solution. Is there a more precise computational way to bridge this gap? Recent developments in machine learning and artificial intelligence suggest that the answer may be yes. These new approaches to inductive learning are based on sophisticated and rational mechanisms of statistical

The role of type and token frequency in using past tense morphemes correctly.

Abstract: Type and token frequency have been thought to be important in the acquisition of past tense morphology, particularly in differentiating regular and irregular forms. In this study we tested the role of frequency in two ways: (1) in bilingual children, who typically use and hear either language less often than monolingual children and (2) cross-linguistically: French and English have different patterns of frequency of regular/irregular verbs. Ten French-English bilingual children, 10 French monolingual and 10 English monolingual children between 4 and 6 years watched a cartoon and re-told the story. The results demonstrated that the bilingual children were less accurate than the monolingual children. Their accuracy in both French and English regular and irregular verbs corresponded to frequency in the input language. These results are consistent with the hypothesis that children learn past tense morphemes by analogy with other words in their vocabularies. We propose a developmental sequence based on conservative generalization across a growing set of verbs.

Development of beliefs about storybook reality.

Abstract: The goal of this research was to assess children's beliefs about the reality status of storybook characters and events. In Experiment 1, 156 preschool age children heard realistic, fantastical, or religious stories, and their understanding of the reality status of the characters and events in the stories was assessed. Results revealed that 3-year-olds were more likely to judge characters as real than were 4- and 5-year-olds, but most children judged all characters as not real for all story types. Children of all ages who heard realistic stories made more claims that the events in the stories could happen in real life than did children who heard fantastical stories. Five-year-olds made significantly more claims that events in religious stories could happen in real life than did younger children. In Experiment 2, 136 4- and 5-year-olds heard similar stories. Results replicated those from Experiment 1, and also indicated a growing awareness of the basic nature of realistic fiction.

Interrelated and interdependent

Abstract: The possibilities for building and nourishing connections among the social, cultural, neuroscientific, biological, and cognitive sciences in the service of understanding children and their development are tremendously exciting. Crossing, and integrating across, disciplinary boundaries, especially those disciplines relating to biology/neuroscience, society/culture, cognition, emotion, perception, and motor function has greatly increased over the last decade and hopefully will increase exponentially in the future. All of these aspects of being human are multiply-interrelated and we need to make far more progress in understanding those interrelations.