A claw is like my hand: comparison supports goal analysis in infants

The development of commitment: Attention for intention

Adhering to a partially defined plan requires an intentional commitment that curbs distracting desires conflicting with the planned course of action, enabling humans to act coherently over time. Two studies (N = 50, 27 girls, ages 5-6, Han Chinese, in Hangzhou, China, 2022.02-2022.03) explored the development of commitment to partial plans in a sequential decision-making task and the underlying cognitive capacity focusing on its correlation to attentional control. Results suggest that only 6-year-olds committed to partial plans (d = .51), and children's commitment ratio was positively correlated with the use of proactive control (r = .40). These findings indicate that intentional commitment does not develop simultaneously with intention understanding, but rather matures gradually with the development of attentional control.

Exploring the feasibility of tensor decomposition for analysis of fNIRS signals: a comparative study with grand averaging method

The analysis of functional near-infrared spectroscopy (fNIRS) signals has not kept pace with the increased use of fNIRS in the behavioral and brain sciences. The popular grand averaging method collapses the oxygenated hemoglobin data within a predefined time of interest window and across multiple channels within a region of interest, potentially leading to a loss of important temporal and spatial information. On the other hand, the tensor decomposition method can reveal patterns in the data without making prior assumptions of the hemodynamic response and without losing temporal and spatial information. The aim of the current study was to examine whether the tensor decomposition method could identify significant effects and novel patterns compared to the commonly used grand averaging method for fNIRS signal analysis. We used two infant fNIRS datasets and applied tensor decomposition (i.e., canonical polyadic and Tucker decompositions) to analyze the significant differences in the hemodynamic response patterns across conditions. The codes are publicly available on GitHub. Bayesian analyses were performed to understand interaction effects. The results from the tensor decomposition method replicated the findings from the grand averaging method and uncovered additional patterns not detected by the grand averaging method. Our findings demonstrate that tensor decomposition is a feasible alternative method for analyzing fNIRS signals, offering a more comprehensive understanding of the data and its underlying patterns.

Compatibility Effects in Young Children's Tool Use: Learning and Transfer

An inherent component of tool-use actions is the transformation of the user's operating movement into the desired effect. In this study, the relevance of this transformation for young children's learning of tool-use actions was investigated. Sixty-four children at the age of 27-30 months learned to use levers which either simply extended (compatible transformation) or reversed (incompatible transformation) their operating movements. Data revealed a compatibility effect as well as transfer effects originating from the two different types of transformations. Furthermore, results suggest that young children's tool-use learning is not a uniform process, but has to be regarded individually depending on the type of transformation.

Getting a grip on early intention understanding: The role of motor, cognitive, and social factors

This chapter considers various factors that facilitate infants' understanding of other people's intentions. As adults, we view the actions people perform around us as intentional, to achieve a goal, rather than idle movements. For example, when observing another person perform a simple grasping action, such as picking up a slice of pizza, we perceive this action as goal-directed. Due to our understanding of the person's intention, we focus more so on the relation between the person and their goal, rather than the motion involved in the action. Infants develop an understanding of intentional agents and their goals within the first year of life. This chapter reviews multiple factors that are at play in facilitating infants' learning about the intentions of others' actions. We consider this from various perspectives, including the role of active experience, sensitivity to behavioral cues, cognitive factors, and social factors. We first review evidence concerning infants' learning of intentional actions from active experience. We then go on to evaluate how this learning could also come about via comparison processes, statistical learning, and use of behavioral cues such as object labeling and action effects. We also review social factors such as infant-directed actions and triadic engagement within social interactions that emerging evidence suggests are helpful in facilitating infants' understanding of other people's actions. Finally, we consider the extent to which these factors interact with one another in different contexts, as well as implications and future directions.

Neural correlates of infant action processing relate to theory of mind in early childhood

The mechanisms that support infant action processing are thought to be involved in the development of later social cognition. While a growing body of research demonstrates longitudinal links between action processing and explicit theory of mind (TOM), it remains unclear why this link emerges in some measures of action encoding and not others. In this paper, we recruit neural measures as a unique lens into which aspects of human infant action processing (i.e., action encoding and action execution; age 7 months) are related to preschool TOM (age 3 years; n = 31). We test whether individual differences in recruiting the sensorimotor system or attention processes during action encoding predict individual differences in TOM. Results indicate that reduced occipital alpha during action encoding predicts TOM at age 3. This finding converges with behavioral work and suggests that attentional processes involved in action encoding may support TOM. We also test whether neural processing during action execution draws on the proto-substrates of effortful control (EC). Results indicate that frontal alpha oscillatory activity during action execution predicted EC at age 3-providing strong novel evidence that infant brain activity is longitudinally linked to EC. Further, we demonstrate that EC mediates the link between the frontal alpha response and TOM. This indirect effect is specific in terms of direction, neural response, and behavior. Together, these findings converge with behavioral research and demonstrate that domain general processes show strong links to early infant action processing and TOM.

Better all by myself: Gaining personal experience, not watching others, improves 3-year-olds' performance in a causal trap task

Children often learn from others' demonstrations, but in the causal domain evidence acquired from observing others may be more ambiguous than evidence generated for oneself. Prior work involving tool-using tasks suggests that observational learning might not provide sufficient information about the causal relations involved, but it remains unclear whether these limitations can be mitigated by providing demonstrations using familiar manual actions rather than unfamiliar tools. We provided 2.5- to 3.5-year-old children (N = 67) with the opportunity to acquire experience with a causal trap task by hand or by tool actively or from observing others. Initially, children either generated their own experience or watched a yoked demonstration; all children then attempted the trap task with the tool. Children who generated their own experience outperformed those who watched the demonstration. Hand or tool use had no effect on performance with a tool. The implications of these findings for scaffolding self-guided learning and for demonstrations involving errors are discussed.

Analogy Lays the Foundation for Two Crucial Aspects of Symbolic Development: Intention and Correspondence

We argue that analogical reasoning, particularly Gentner's (1983, 2010) structure-mapping theory, provides an integrative theoretical framework through which we can better understand the development of symbol use. Analogical reasoning can contribute both to the understanding of others' intentions and the establishment of correspondences between symbols and their referents, two crucial components of symbolic understanding. We review relevant research on the development of symbolic representations, intentionality, comparison, and similarity, and demonstrate how structure-mapping theory can shed light on several ostensibly disparate findings in the literature. Focusing on visual symbols (e.g., scale models, photographs, and maps), we argue that analogy underlies and supports the understanding of both intention and correspondence, which may enter into a reciprocal bootstrapping process that leads children to gain the prodigious human capacity of symbol use.

Structure Mapping for Social Learning

Analogical reasoning is a foundational tool for human learning, allowing learners to recognize relational structures in new events and domains. Here I sketch some grounds for understanding and applying analogical reasoning in social learning. The social world is fundamentally characterized by relations between people, with common relational structures-such as kinships and social hierarchies-forming social units that dictate social behaviors. Just as young learners use analogical reasoning for learning relational structures in other domains-spatial relations, verbs, relational categories-analogical reasoning ought to be a useful cognitive tool for acquiring social relations and structures.

Social Models Enhance Apes' Memory for Novel Events

Nonhuman primates are more likely to learn from the actions of a social model than a non-social "ghost display", however the mechanism underlying this effect is still unknown. One possibility is that live models are more engaging, drawing increased attention to social stimuli. However, recent research with humans has suggested that live models fundamentally alter memory, not low-level attention. In the current study, we developed a novel eye-tracking paradigm to disentangle the influence of social context on attention and memory in apes. Tested in two conditions, zoo-housed apes (2 gorillas, 5 chimpanzees) were familiarized to videos of a human hand (social condition) and mechanical claw (non-social condition) constructing a three-block tower. During the memory test, subjects viewed side-by-side pictures of the previously-constructed block tower and a novel block tower. In accordance with looking-time paradigms, increased looking time to the novel block tower was used to measure event memory. Apes evidenced memory for the event featuring a social model, though not for the non-social condition. This effect was not dependent on attention differences to the videos. These findings provide the first evidence that, like humans, social stimuli increase nonhuman primates' event memory, which may aid in information transmission via social learning.

Infants' observation of tool-use events over the first year of life

How infants observe a goal-directed instrumental action provides a unique window into their understanding of others' behavior. In this study, we investigated eye-gaze patterns while infants observed events in which an actor used a tool on an object. Comparisons among 4-, 7-, 10-, and 12-month-old infants and adults reveal changes in infants' looking patterns with age; following an initial face bias, infants' scan path eventually shows a dynamic integration of both the actor's face and the objects on which they act. This shift may mark a transition in infants' understanding of the critical components of tool-use events and their understanding of others' behavior.

On the other hand: Increased cortical activation to human versus mechanical hands in infants

There is a large body of work demonstrating that infants are sensitive to the distinction between human and mechanical entities from the early months of life, and have different expectations for the way these entities move and interact. The current work investigates the extent to which the functional organization of the immature brain reflects these early emerging sensitivities. Infants aged 8months watched two kinds of hands (human or mechanical) engage in two kinds of events (one with a functional outcome and one without). Using functional near-infrared spectroscopy (fNIRS), we assessed hemodynamic activation in the left and right temporal and temporal-occipital cortex in response to these events. The neuroimaging data revealed a significantly greater increase in activation in the right middle-posterior temporal cortex to events executed by the human than the mechanical hand; the event in which the hand engaged (function or non-function) did not significantly influence hemodynamic responses. In comparison, the left middle-temporal cortex showed significantly greater activation to events executed by the human than mechanical hand, but only when the events were functionally relevant. That is, the left middle-posterior temporal cortex responded selectively to human (as compared to mechanical) agents, but only in the context of functionally relevant actions on objects. These results reveal that the immature brain is functionally specialized to support infants' processing of human and non-human agents as distinct entities. These results also shed light on the cognitive and cortical mechanisms that guide infants' learning about agentive action and object function.

Motor System Activation Predicts Goal Imitation in 7-Month-Old Infants

The current study harnessed the variability in infants' neural and behavioral responses as a novel method for evaluating the potential relations between motor system activation and social behavior. We used electroencephalography (EEG) to record neural activity as 7-month-old infants observed and responded to the actions of an experimenter. To determine whether motor system activation predicted subsequent imitation behavior, we assessed event-related desynchronization (ERD) at central sites during action observation as a function of subsequent behavior. Greater mu desynchronization over central sites was observed when infants subsequently reproduced the experimenter's goal than when they did not reproduce the goal and instead selected the nongoal object. We also found that mu desynchronization during action execution predicted the infants' later propensity to reproduce the experimenter's goal-directed behavior. These results provide the first evidence that motor system activation predicts the imitation of other individuals' goals during infancy.

Action Experience Changes Attention to Kinematic Cues

The current study used remote corneal reflection eye-tracking to examine the relationship between motor experience and action anticipation in 13-months-old infants. To measure online anticipation of actions infants watched videos where the actor’s hand provided kinematic information (in its orientation) about the type of object that the actor was going to reach for. The actor’s hand orientation either matched the orientation of a rod (congruent cue) or did not match the orientation of the rod (incongruent cue). To examine relations between motor experience and action anticipation, we used a 2 (reach first vs. observe first) × 2 (congruent kinematic cue vs. incongruent kinematic cue) between-subjects design. We show that 13-months-old infants in the observe first condition spontaneously generate rapid online visual predictions to congruent hand orientation cues and do not visually anticipate when presented incongruent cues. We further demonstrate that the speed that these infants generate predictions to congruent motor cues is correlated with their own ability to pre-shape their hands. Finally, we demonstrate that following reaching experience, infants generate rapid predictions to both congruent and incongruent hand shape cues—suggesting that short-term experience changes attention to kinematics.

Infants' observation of others' actions: Brief movement-specific visual experience primes motor representations

Recent research suggests that infants' observation of others' reaching actions activates corresponding motor representations which develop with their motor experience. Contralateral reaching develops a few months later than ipsilateral reaching, and 9-month-old infants are less likely to map the observation of these reaches to their motor representations. The goal of the current study was to test whether a brief familiarization with contralateral reaching is sufficient to prime this less developed motor representation to increase the likelihood of its activation. In Experiment 1, infants were familiarized with contralateral reaching before they were tested in an observational version of the A-not-B paradigm. A significant number of infants searched incorrectly, suggesting that the observation of contralateral reaching primed their motor representations. In Experiment 2, infants were familiarized with ipsilateral reaching, which shared the goals but not the movements associated with the contralateral reaches observed during testing, and they did not show a search bias. Taken together, these results suggest that a brief familiarization with a movement-specific behaviour facilitates the direct matching of observed and executed actions.

Shifting goals: effects of active and observational experience on infants' understanding of higher order goals

Action perception links have been argued to support the emergence of action understanding, but their role in infants’ perception of distal goals has not been fully investigated. The current experiments address this issue. During the development of means-end actions, infants shift their focus from the means of the action to the distal goal. In Experiment One, we evaluated whether this same shift in attention (from the means to the distal goal) when learning to produce multi-step actions is reflected in infants’ perception of others’ means-end actions. Eight-months-old infants underwent active training in means-end action production and their subsequent analysis of an observed means-end action was assessed in a visual habituation paradigm. Infants’ degree of success in the training paradigm was related to their subsequent interpretation of the observed action as directed at the means versus the distal goal. In Experiment Two, observational and control manipulations provided evidence that these effects depended on the infants’ active engagement in the means-end actions. These results suggest that the processes that give rise to means-end structure in infants’ motor behavior also support the emergence of means-end structure in their analysis of others’ goals.

A developmental perspective on action and social cognition

The target article argues that developmental processes are key to understanding the mirror neuron system, yet neglects several bodies of developmental research that are informative for doing so. Infants' actions and action understanding are structured by goals, and the former lends structure to the latter. Evaluating the origins and functions of mirror neurons depends on integrating investigations of neural, social-cognitive and motor development.

The importance of witnessed agency in chimpanzee social learning of tool use

Social learning refers to individuals learning from others, including information gained through indirect social influences, such as the results of others' actions and changes in the physical environment. One method to determine the relative influence of these varieties of information is the 'ghost display', in which no model is involved, but subjects can watch the results that a model would produce. Previous research has shown mixed success by chimpanzees (Pan troglodytes) learning from ghost displays, with some studies suggesting learning only in relatively simple tasks. To explore whether the failure of chimpanzees to learn from a ghost display may be due to neophobia when tested singly or a requirement for more detailed information for complex tasks, we presented ghost displays of a tool-use task to chimpanzees in their home social groups. Previous tests have revealed that chimpanzees are unable to easily solve this tool-use task asocially, or learn from ghost displays when tested singly, but can learn after observing conspecifics in a group setting. In the present study, despite being tested in a group situation, chimpanzees still showed no success in solving the task via trial-and-error learning, in a baseline condition, nor in learning the task from the ghost display. Simply being in the presence of their group mates and being shown the affordances of the task was not sufficient to encourage learning. Following this, in an escalating series of tests, we examined the chimpanzees' ability to learn from a demonstration by models with agency: (1) a human; (2) video footage of a chimpanzee; (3) a live chimpanzee model. In the first two of these 'social' conditions, subjects showed limited success. By the end of the final open diffusion phase, which was run to determine whether this new behavior would be transmitted among the group after seeing a successful chimpanzee use the task, 83% of chimpanzees were now successful. This confirmed a marked overall effect of observing animate conspecific modeling, in contrast to the ghost condition. This article is part of a Special Issue entitled: insert SI title.

Great Apes Generate Goal-Based Action Predictions

To examine great apes’ on-line prediction of other individuals’ actions, we used an eye-tracking technique and an experimental paradigm previously used to test human infants. Twenty-two great apes, including bonobos, chimpanzees, and orangutans, were familiarized to movie clips of a human hand reaching to grasp one of two objects. Then the objects’ locations were swapped, and in the test event, the hand made an incomplete reach between the objects. In a control condition, a mechanical claw performed the same actions. The apes predictively looked at the familiarized goal object rather than the familiarized location when viewing the hand action in the test event. However, they made no prediction when viewing the claw action. These results are similar to those reported previously for human infants, and predictive looking did not differ among the three species of great apes. Thus, great apes make on-line goal-based predictions about the actions of other individuals; this skill is not unique to humans but is shared more widely among primates.

Making smart social judgments takes time: infants' recruitment of goal information when generating action predictions

Previous research has shown that young infants perceive others' actions as structured by goals. One open question is whether the recruitment of this understanding when predicting others' actions imposes a cognitive challenge for young infants. The current study explored infants' ability to utilize their knowledge of others' goals to rapidly predict future behavior in complex social environments and distinguish goal-directed actions from other kinds of movements. Fifteen-month-olds (N = 40) viewed videos of an actor engaged in either a goal-directed (grasping) or an ambiguous (brushing the back of her hand) action on a Tobii eye-tracker. At test, critical elements of the scene were changed and infants' predictive fixations were examined to determine whether they relied on goal information to anticipate the actor's future behavior. Results revealed that infants reliably generated goal-based visual predictions for the grasping action, but not for the back-of-hand behavior. Moreover, response latencies were longer for goal-based predictions than for location-based predictions, suggesting that goal-based predictions are cognitively taxing. Analyses of areas of interest indicated that heightened attention to the overall scene, as opposed to specific patterns of attention, was the critical indicator of successful judgments regarding an actor's future goal-directed behavior. These findings shed light on the processes that support “smart” social behavior in infants, as it may be a challenge for young infants to use information about others' intentions to inform rapid predictions.

Mirroring and the development of action understanding

The discovery of mirror neurons in the monkey motor cortex has inspired wide-ranging hypotheses about the potential relationship between action control and social cognition. In this paper, we consider the hypothesis that this relationship supports the early development of a critical aspect of social understanding, the ability to analyse others' actions in terms of goals. Recent investigations of infant action understanding have revealed rich connections between motor development and the analysis of goals in others' actions. In particular, infants' own goal-directed actions influence their analysis of others' goals. This evidence indicates that the cognitive systems that drive infants' own actions contribute to their analysis of goals in others' actions. These effects occur at a relatively abstract level of analysis both in terms of the structure infants perceive in others' actions and relevant structure in infants' own actions. Although the neural bases of these effects in infants are not yet well understood, current evidence indicates that connections between action production and action perception in infancy involve the interrelated neural systems at work in generating planned, intelligent action.

Labels Facilitate Infants' Comparison of Action Goals

Understanding the actions of others depends on the insight that these actions are structured by intentional relations. In a number of conceptual domains, comparison with familiar instances has been shown to support children's and adults' ability to discern the relational structure of novel instances. Recent evidence suggests that this process supports infants' analysis of others' goal-directed actions (Gerson & Woodward, 2012). The current studies evaluated whether labeling, which has been shown to support relational learning in other domains, also supports infants' sensitivity to the goal structure of others' actions. Ten-month-old infants observed events in which a familiar action, grasping, was aligned (simultaneously presented) with a novel tool use action, and both actions were accompanied by a matched label. Following this training, infants responded systematically to the goal structure of the tool use actions in a goal imitation paradigm. In control conditions, when the aligned actions were accompanied by non-word vocalizations, or when labeling occurred without aligned actions, infants did not respond systematically to the tool use action. These findings indicate that labels supported infants' comparison of the aligned actions, and this comparison facilitated their understanding of the novel action as goal-directed.

The joint role of trained, untrained, and observed actions at the origins of goal recognition

Recent findings across a variety of domains reveal the benefits of self-produced experience on object exploration, object knowledge, attention, and action perception. The influence of active experience may be particularly important in infancy, when motor development is undergoing great changes. Despite the importance of self-produced experience, we know that infants and young children are eventually able to gain knowledge through purely observational experience. In the current work, three-month-old infants were given experience with object-directed actions in one of three forms and their recognition of the goal of grasping actions was then assessed in a habituation paradigm. All infants were given the chance to manually interact with the toys without assistance (a difficult task for most three-month-olds). Two of the three groups were then given additional experience with object-directed actions, either through active training (in which Velcro mittens helped infants act more efficiently) or observational training. Findings support the conclusion that self-produced experience is uniquely informative for action perception and suggest that individual differences in spontaneous motor activity may interact with observational experience to inform action perception early in life.

Learning from their own actions: the unique effect of producing actions on infants' action understanding

Prior research suggests that infants' action production affects their action understanding, but little is known about the aspects of motor experience that render these effects. In Study 1, the relative contributions of self-produced (n = 30) and observational (n = 30) action experience on 3-month-old infants' action understanding was assessed using a visual habituation paradigm. In Study 2, generalization of training to a new context was examined (n = 30). Results revealed a unique effect of active over observational experience. Furthermore, findings suggest that benefits of trained actions do not generalize broadly, at least following brief training.

Neurocognitive mechanisms underlying social learning in infancy: infants' neural processing of the effects of others' actions

Social transmission of knowledge is one of the reasons for human evolutionary success, and it has been suggested that already human infants possess eminent social learning abilities. However, nothing is known about the neurocognitive mechanisms that subserve infants' acquisition of novel action knowledge through the observation of other people's actions and their consequences in the physical world. In an electroencephalogram study on social learning in infancy, we demonstrate that 9-month-old infants represent the environmental effects of others' actions in their own motor system, although they never achieved these effects themselves before. The results provide first insights into the neurocognitive basis of human infants' unique ability for social learning of novel action knowledge.

The nature of goal-directed action representations in infancy

A critical question for developmental psychologists concerns how representations in infancy are best characterized. Past and current research provides paradoxical evidence regarding the nature of early representations: in some ways, infants appear to build concrete and specific representations that guide their online perception and understanding of different events; in other ways, infants appear to possess abstract representations that support inferences regarding unseen event outcomes. Characterizing the nature of early representations across domains is a central charge for developmentalists because this task can provide important information regarding the underlying learning process or processes that drive development. Yet, little existing work has attempted to resolve this paradox by characterizing the ways in which infants' representations may have both abstract and concrete elements. The goal of this chapter is to take a close look at infants' early representations of goal-directed action in order to describe the nature of these representations. We first discuss the nature of representations of action that infants build through acting on the world and argue that these representations possess both concrete and abstract elements. On the one hand, infants appear to build representations of action that stress goal-relevant features of actions in an action- or event-specific fashion, suggesting specificity or concreteness. On the other hand, these representations are sufficiently abstract to not only drive action but also support infants' perception of others actions and to support inferences regarding unseen action outcomes. We next discuss evidence to suggest that by the end of the first year of life, infants possess increasingly abstract representations of the actions of others and use contextual cues, including linguistic statements accompanying action, to flexibly specify the level of representational specificity. We further consider the possibility that language may play a role in infants' ability to build more abstract representations of goal-directed action.

Infants generate goal-based action predictions

Predicting the actions of others is critical to smooth social interactions. Prior work suggests that both understanding and anticipation of goal-directed actions appears early in development. In this study, on-line goal prediction was tested explicitly using an adaptation of Woodward's (1998) paradigm for an eye-tracking task. Twenty 11-month-olds were familiarized to movie clips of a hand reaching to grasp one of two objects. Then object locations were swapped, and the hand made an incomplete reach between the objects. Here, infants reliably made their first look from the hand to the familiarized goal object, now in a new location. A separate control condition of 20 infants familiarized to the same movements of an unfamiliar claw revealed the opposite pattern: reliable prediction to the familiarized location, rather than the familiarized object. This study suggests that by 11 months infants actively use goal analysis to generate on-line predictions of an agent's next action.