Sounds of Hidden Agents: The Development of Causal Reasoning About Musical Sounds

Listening to music activates representations of movement and social agents. Why? We test whether causal reasoning plays a role, and find that from childhood, people can intuitively reason about how musical sounds were generated, inferring the events and agents that caused the sounds. In Experiment 1 (N = 120, pre-registered), 6-year-old children and adults inferred the presence of an unobserved animate agent from hearing musical sounds, by integrating information from the sounds' timing with knowledge of the visual context. Thus, children inferred that an agent was present when the sounds would require self-propelled movement to produce, given the current visual context (e.g., unevenly-timed notes, from evenly-spaced xylophone bars). Consistent with Bayesian causal inference, this reasoning was flexible, allowing people to make inferences not only about unobserved agents, but also the structure of the visual environment in which sounds were produced (in Experiment 2, N = 114). Across experiments, we found evidence of developmental change: Younger children ages 4-5 years failed to integrate auditory and visual information, focusing solely on auditory features (Experiment 1) and failing to connect sounds to visual contexts that produced them (Experiment 2). Our findings support a developmental account in which before age 6, children's reasoning about the causes of musical sounds is limited by failure to integrate information from multiple modalities when engaging in causal reasoning. By age 6, children and adults integrate auditory information with other knowledge to reason about how musical sounds were generated, and thereby link musical sounds with the agents, contexts, and events that caused them.

Learning Loopholes: The Development of Intentional Misunderstandings in Children

What do children do when they do not want to obey but cannot afford to disobey? Might they, like adults, feign misunderstanding and seek out loopholes? Across four studies (N = 723; 44% female; USA; majority White; data collected 2020-2023), we find that loophole behavior emerges around ages 5 to 6 (Study 1, 3-18 years), that children think loopholes will get them into less trouble than non-compliance (Study 2, 4-10 years), predict that other children will be more likely to exploit loopholes when goals conflict (Study 3, 5-10 years), and are increasingly able to generate loopholes themselves (Study 4, 5-10 years). This work provides new insights on how children navigate the gray area between compliance and defiance and the development of loophole behavior across early and middle childhood.

Children's cost-benefit analysis about agents who act for the greater good

Acting for the greater good often involves paying a personal cost to benefit the collective. In two studies, we investigate how children (N = 184, Mage = 8.02 years, SD = 1.15, Range = 6.00-9.99 years) use information about costs and consequences when reasoning about agents who act for the greater good. Children were told about a novel community, in which individuals could pay a cost to prevent a consequence (e.g., holding up an umbrella to prevent rain from flooding the village). In Study 1, children saw two scenarios, one where costs were minor and consequences were major, and one where the opposite was true (major cost, minor consequence). Children in the former condition expected more agents to engage in costly behavior and judged refusal to engage in costly behavior as less permissible. In Study 2 we separately manipulated cost and consequence to see which factor influences children's judgments most - cost or consequence. Here, children expected agents to pay a minor cost regardless of consequence, and only expected agents to pay a major cost when consequence was also major. In their permissibility judgments, children judged refusal to engage in costly behavior to be less permissible when consequences were major than when they were minor, regardless of cost. These findings suggest that children are making principled judgments about acting for the greater good - both cost and consequence determine when we are expected to act, but consequence seems to be a particularly key factor in deciding when inaction is permissible.

Young Children's Understanding of Helping as Increasing Another Agent's Utility

Instrumental helping is one of the paradigmatic "prosocial" behaviors featured in developmental research on sociomoral reasoning, but not much is known about how children recognize instances of helping behaviors or understand the term 'help'. Here, we examined whether young children represent helping as a second-order goal and take it to mean increasing the utility of another agent. In Study 1, we tested whether 12-month-old infants would expect an agent who previously helped to perform an action that reduced the Helpee's action cost. We found that while infants expected agents to act individually efficiently (Experiment 1C), they did not expect the agent to choose the action that maximally reduced the Helpee's cost compared to an action that reduced the cost less (Experiment 1A) or not at all (Experiment 1B). In Study 2, we examined whether three-year-old preschoolers (1) maximize a Helpee's cost reduction when prompted to help in a first-person task, and (2) identify in a third-party context which of two agents, performing superficially similar behaviors with varying effects on the Helpee's action options, actually helped. Contrary to our predictions, preschoolers did not help in a way that maximally reduced the Helpee's cost in (1). In (2), however, they indicated that the agent who reduced the Helpee's action cost was the one who helped. Taken together, these results support the proposal that, at least by preschool age, children possess a second-order utility-based concept of helping, but that they may not exhibit efficiency when choosing their own helping actions.

Contextualizing predictive minds

The structure of human memory seems to be optimized for efficient prediction, planning, and behavior. We propose that these capacities rely on a tripartite structure of memory that includes concepts, events, and contexts-three layers that constitute the mental world model. We suggest that the mechanism that critically increases adaptivity and flexibility is the tendency to contextualize. This tendency promotes local, context-encoding abstractions, which focus event- and concept-based planning and inference processes on the task and situation at hand. As a result, cognitive contextualization offers a solution to the frame problem-the need to select relevant features of the environment from the rich stream of sensorimotor signals. We draw evidence for our proposal from developmental psychology and neuroscience. Adopting a computational stance, we present evidence from cognitive modeling research which suggests that context sensitivity is a feature that is critical for maximizing the efficiency of cognitive processes. Finally, we turn to recent deep-learning architectures which independently demonstrate how context-sensitive memory can emerge in a self-organized learning system constrained by cognitively-inspired inductive biases.

Perceptual and conceptual novelty independently guide infant looking behaviour: a systematic review and meta-analysis

Human infants are born with their eyes open and an otherwise limited motor repertoire; thus, studies measuring infant looking are commonly used to investigate the developmental origins of perception and cognition. However, scholars have long expressed concerns about the reliability and interpretation of looking behaviours. We evaluated these concerns using a pre-registered ( https://osf.io/jghc3 ), systematic meta-analysis of 76 published and unpublished studies of infants' early physical and psychological reasoning (total n = 1,899; 3- to 12-month-old infants; database search and call for unpublished studies conducted July to August 2022). We studied two effects in the same datasets: looking towards expected versus unexpected events (violation of expectation (VOE)) and looking towards visually familiar versus visually novel events (perceptual novelty (PN)). Most studies implemented methods to minimize the risk of bias (for example, ensuring that experimenters were naive to the conditions and reporting inter-rater reliability). There was mixed evidence about publication bias for the VOE effect. Most centrally to our research aims, we found that these two effects varied systematically-with roughly equal effect sizes (VOE, standardized mean difference 0.290 and 95% confidence interval (0.208, 0.372); PN, standardized mean difference 0.239 and 95% confidence interval (0.109, 0.369))-but independently, based on different predictors. Age predicted infants' looking responses to unexpected events, but not visually novel events. Habituation predicted infants' looking responses to visually novel events, but not unexpected events. From these findings, we suggest that conceptual and perceptual novelty independently influence infants' looking behaviour.

Ambivalence by design: A computational account of loopholes

Loopholes offer an opening. Rather than comply or directly refuse, people can subvert an intended request by an intentional misunderstanding. Such behaviors exploit ambiguity and under-specification in language. Using loopholes is commonplace and intuitive in everyday social interaction, both familiar and consequential. Loopholes are also of concern in the law, and increasingly in artificial intelligence. However, the computational and cognitive underpinnings of loopholes are not well understood. Here, we propose a utility-theoretic recursive social reasoning model that formalizes and accounts for loophole behavior. The model captures the decision process of a loophole-aware listener, who trades off their own utility with that of the speaker, and considers an expected social penalty for non-cooperative behavior. The social penalty is computed through the listener's recursive reasoning about a virtual naive observer's inference of a naive listener's social intent. Our model captures qualitative patterns in previous data, and also generates new quantitative predictions consistent with novel studies (N = 265). We consider the broader implications of our model for other aspects of social reasoning, including plausible deniability and humor.

The Cognitive Architecture of Infant Attachment

Meta-analytic evidence indicates that the quality of the attachment relationship that infants establish with their primary caregiver has enduring significance for socioemotional and cognitive outcomes. However, the mechanisms by which early attachment experiences contribute to subsequent development remain underspecified. According to attachment theory, early attachment experiences become embodied in the form of cognitive-affective representations, referred to as internal working models (IWMs), that guide future behavior. Little is known, however, about the cognitive architecture of IWMs in infancy. In this article, we discuss significant advances made in the field of infant cognitive development and propose that leveraging insights from this research has the potential to fundamentally shape our understanding of the cognitive architecture of attachment representations in infancy. We also propose that the integration of attachment research into cognitive research can shed light on the role of early experiences, individual differences, and stability and change in infant cognition, as well as open new routes of investigation in cognitive studies, which will further our understanding of human knowledge. We provide recommendations for future research throughout the article and conclude by using our collaborative research as an example.

Do toddlers reason about other people's experiences of objects? A limit to early mental state reasoning

Human social life requires an understanding of the mental states of one's social partners. Two people who look at the same objects often experience them differently, as a twinkling light or a planet, a 6 or a 9, and a random cat or Cleo, their pet. Indeed, a primary purpose of communication is to share distinctive experiences of objects or events. Here, we test whether toddlers (14-15 months) are sensitive to another agent's distinctive experiences of pictures when determining the goal underlying the agent's actions in a minimally social context. We conducted nine experiments. Across seven of these experiments (n = 206), toddlers viewed either videotaped or live events in which an actor, whose perspective differed from their own, reached (i) for pictures of human faces that were upright or inverted or (ii) for pictures that depicted a rabbit or a duck at different orientations. Then either the actor or the toddler moved to a new location that aligned their perspectives, and the actor alternately reached to each of the two pictures. By comparing toddlers' looking to the latter reaches, we tested whether their goal attributions accorded with the actor's experience of the pictured objects, with their own experience of the pictured objects, or with no consistency. In no experiment did toddlers encode the actor's goal in accord with his experiences of the pictures. In contrast, in a similar experiment that manipulated the visibility of a picture rather than the experience that it elicited, toddlers (n = 32) correctly expected the actor's action to depend on what was visible and occluded to him, rather than to themselves. In a verbal version of the tasks, older children (n = 35) correctly inferred the actor's goal in both cases. These findings provide further evidence for a dissociation between two kinds of mental state reasoning: When toddlers view an actor's object-directed action under minimally social conditions, they take account of the actor's visual access to the object but not the actor's distinctive experience of the object.

Optimizing competence in the service of collaboration

In order to efficiently divide labor with others, it is important to understand what our collaborators can do (i.e., their competence). However, competence is not static-people get better at particular jobs the more often they perform them. This plasticity of competence creates a challenge for collaboration: For example, is it better to assign tasks to whoever is most competent now, or to the person who can be trained most efficiently "on-the-job"? We conducted four experiments (N=396) that examine how people make decisions about whom to train (Experiments 1 and 3) and whom to recruit (Experiments 2 and 4) to a collaborative task, based on the simulated collaborators' starting expertise, the training opportunities available, and the goal of the task. We found that participants' decisions were best captured by a planning model that attempts to maximize the returns from collaboration while minimizing the costs of hiring and training individual collaborators. This planning model outperformed alternative models that based these decisions on the agents' current competence, or on how much agents stood to improve in a single training step, without considering whether this training would enable agents to succeed at the task in the long run. Our findings suggest that people do not recruit and train collaborators based solely on their current competence, nor solely on the opportunities for their collaborators to improve. Instead, people use an intuitive theory of competence to balance the costs of hiring and training others against the benefits to the collaboration.

Toddlers Prefer Agents Who Help Those Facing Harder Tasks

Capacities to understand and evaluate others' actions are fundamental to human social life. Infants and toddlers are sensitive to the costs of others' actions, infer others' values from the costs of the actions they take, and prefer those who help others to those who hinder them, but it is largely unknown whether and how cost considerations inform early understanding of third-party prosocial actions. In three experiments (N = 94), we asked whether 16-month-old toddlers value agents who selectively help those who need it most. Presented with two agents who attempted two tasks, toddlers preferentially looked to and touched someone who helped the agent in greater need, both when one agent's task required more effort and when the tasks were the same but one agent was weaker. These results provide evidence that toddlers engage in need-based evaluations of helping, applying their understanding of action utilities to their social evaluations.

Perceiving others' cognitive effort through movement: Path length, speed, and time

Effort perception is a crucial capacity underpinning characteristically human forms of sociality, allowing us to learn about others' mental states and about the value of opportunities afforded by our environment, and supporting our ability to cooperate efficiently and fairly. Despite the crucial importance and prevalence of effort perception, little is known about the mechanisms underpinning it. Across two online experiments (N = 462), we tested whether adults estimate others' cognitive effort costs by tracking perceptible properties of movement such as path length, time, and speed. The results showed that only time had a consistent effect on effort perception, that is, participants rated longer time as more effortful. Taken together, our results suggest that within the context of our task-observing an agent deciphering a captcha-people rely on the time of others' actions to estimate their cognitive effort costs.

Choosing Among Undesirable Options: Children Consider Desirability of Available Choices in Evaluation of Socially Mindful Actions

Previous studies show that adults and children evaluate the act of leaving a choice for others as prosocial, and have termed such actions as socially mindful actions. The current study investigates how the desirability of the available options (i.e., whether the available options are desirable or not) may influence adults' and children's evaluation of socially mindful actions. Children (N = 120, 4- to 6-year-olds) and adults (N = 124) were asked to evaluate characters selecting items for themselves from a set of three items-two identical items and one unique item-in a way that either leaves a choice (two diverse items) or leaves no choice (two identical items) for the next person (i.e., the beneficiary). We manipulated whether the available options were either desirable or undesirable (i.e., damaged). We found that adults' and 6-year-olds' evaluation of socially mindful actions is moderated by the desirability of the options. Although they evaluate the act of leaving a choice for others as nicer than the act of leaving no choice both when the choosing options are desirable and when they are undesirable, the discrepancy in the evaluation becomes significantly smaller when the choosing options are undesirable. We also found that inference of the beneficiary's feeling underlies social evaluation of the actor leaving a choice (or not). These findings suggest that children consider both the diversity of options left and the desirability of the available options in understanding and evaluating socially mindful acts.

Better Together: 14-Month-Old Infants Expect Agents to Cooperate

Humans engage in cooperative activities from early on and the breadth of human cooperation is unparalleled. Human preference for cooperation might reflect cognitive and motivational mechanisms that drive engagement in cooperative activities. Here we investigate early indices of humans' cooperative abilities and test whether 14-month-old infants expect agents to prefer cooperative over individual goal achievement. Three groups of infants saw videos of agents facing a choice between two actions that led to identical rewards but differed in the individual costs. Our results show that, in line with prior research, infants expect agents to make instrumentally rational choices and prefer the less costly of two individual action alternatives. In contrast, when one of the action alternatives is cooperative, infants expect agents to choose cooperation over individual action, even though the cooperative action demands more effort from each agent to achieve the same outcome. Finally, we do not find evidence that infants expect agents to choose the less costly alternative when both options entail cooperative action. Combined, these results indicate an ontogenetically early expectation of cooperation, and raise interesting implications and questions regarding the nature of infants' representations of cooperative actions and their utility.

Computational Social Psychology

Social psychologists attempt to explain how we interact by appealing to basic principles of how we think. To make good on this ambition, they are increasingly relying on an interconnected set of formal tools that model inference, attribution, value-guided decision making, and multi-agent interactions. By reviewing progress in each of these areas and highlighting the connections between them, we can better appreciate the structure of social thought and behavior, while also coming to understand when, why, and how formal tools can be useful for social psychologists.

The Role of Agentive and Physical Forces in the Neural Representation of Motion Events

How does the brain represent information about motion events in relation to agentive and physical forces? In this study, we investigated the neural activity patterns associated with observing animated actions of agents (e.g., an agent hitting a chair) in comparison to similar movements of inanimate objects that were either shaped solely by the physics of the scene (e.g., gravity causing an object to fall down a hill and hit a chair) or initiated by agents (e.g., a visible agent causing an object to hit a chair). Using an fMRI-based multivariate pattern analysis (MVPA), this design allowed testing where in the brain the neural activity patterns associated with motion events change as a function of, or are invariant to, agentive versus physical forces behind them. A total of 29 human participants (nine male) participated in the study. Cross-decoding revealed a shared neural representation of animate and inanimate motion events that is invariant to agentive or physical forces in regions spanning frontoparietal and posterior temporal cortices. In contrast, the right lateral occipitotemporal cortex showed a higher sensitivity to agentive events, while the left dorsal premotor cortex was more sensitive to information about inanimate object events that were solely shaped by the physics of the scene.

Infants expect friends, but not rivals, to be happy for each other when they succeed

A friend telling you good news earns them a smile while witnessing a rival win an award may make you wrinkle your nose. Emotions arise not just from people's own circumstances, but also from the experiences of friends and rivals. Across three moderated, online looking time studies, we asked if human infants hold expectations about others' vicarious emotions and if they expect those emotions to be guided by social relationships. Ten- and 11-month-old infants (N = 154) expected an observer to be happy rather than sad when the observer watched a friend successfully jump over a wall; infants looked longer at the sad response compared to the happy response. In contrast, infants did not expect the observer to be happy when the friend failed, nor when a different, rival jumper succeeded; infants' looking times to the two emotion responses in these conditions were not reliably different. These results suggest that infants are able to integrate knowledge across social contexts to guide expectations about vicarious emotional responses. Here infants connected an understanding of agents' goals and their outcomes with knowledge of social relationships to infer an emotion response. Biased concern for friends but not adversaries is not just a descriptive feature of human relationships, but an expectation about the social world present from early in development. Further, the successful integration of these information types welcomes the possibility that infants can jointly reason about goals, emotions, and social relationships under an intuitive theory of psychology. RESEARCH HIGHLIGHTS: 11-month-old infants use knowledge of relationships to make inferences about others' vicarious emotions. In Experiment 1 infants expected an observer to respond happily to a friend's success but not their failure. Experiments 2 and 3 varied the relationship between the observer and actor and found that infants' expectation of vicarious happiness is strongest for positive relationships and absent for negative relationships. The results may reflect an intuitive psychology in which infants expect friends to adopt concern for one another's goals and to thus experience one another's successes as rewarding.

Seeing and understanding epistemic actions

Many actions have instrumental aims, in which we move our bodies to achieve a physical outcome in the environment. However, we also perform actions with epistemic aims, in which we move our bodies to acquire information and learn about the world. A large literature on action recognition investigates how observers represent and understand the former class of actions; but what about the latter class? Can one person tell, just by observing another person's movements, what they are trying to learn? Here, five experiments explore epistemic action understanding. We filmed volunteers playing a "physics game" consisting of two rounds: Players shook an opaque box and attempted to determine i) the number of objects hidden inside, or ii) the shape of the objects inside. Then, independent subjects watched these videos and were asked to determine which videos came from which round: Who was shaking for number and who was shaking for shape? Across several variations, observers successfully determined what an actor was trying to learn, based only on their actions (i.e., how they shook the box)-even when the box's contents were identical across rounds. These results demonstrate that humans can infer epistemic intent from physical behaviors, adding a new dimension to research on action understanding.

Actual and counterfactual effort contribute to responsibility attributions in collaborative tasks

How do people judge responsibility in collaborative tasks? Past work has proposed a number of metrics that people may use to attribute blame and credit to others, such as effort, competence, and force. Some theories consider only the actual effort or force (individuals are more responsible if they put forth more effort or force), whereas others consider counterfactuals (individuals are more responsible if some alternative behavior on their or their collaborator's part could have altered the outcome). Across four experiments (N=717), we found that participants' judgments are best described by a model that considers both actual and counterfactual effort. This finding generalized to an independent validation data set (N=99). Our results thus support a dual-factor theory of responsibility attribution in collaborative tasks.

Infants are sensitive to the social signaling value of shared inefficient behaviors

Actions that are blatantly inefficient to achieve non-social goals are often used to convey information about agents' social affiliation, as in the case of rituals. We argue that when reproduced, actions that are individually inefficient acquire a social signaling value owing to the mechanisms that support humans' intuitive analysis of actions. We tested our hypothesis on 15-month-old infants who were familiarized with an agent that reproduced or merely observed the actions of efficient and inefficient individuals. Subsequently, we measured the infants' expectations of the agent's preferences for efficient and inefficient individuals. Our results confirmed that when agents act alone, infants expect a third-party to prefer efficient over inefficient agents. However, this pattern is entirely flipped if the third-party reproduces the agents' actions. In that case, infants expect inefficient agents to be preferred over efficient ones. Thus, reproducing actions whose rational basis is elusive can serve a critical social signaling function, accounting for why such behaviors are pervasive in human groups.

People can use the placement of objects to infer communicative goals

Beyond words and gestures, people have a remarkable capacity to communicate indirectly through everyday objects: A hat on a chair can mean it is occupied, rope hanging across an entrance can mean we should not cross, and objects placed in a closed box can imply they are not ours to take. How do people generate and interpret the communicative meaning of objects? We hypothesized that this capacity is supported by social goal inference, where observers recover what social goal explains an object being placed in a particular location. To test this idea, we study a category of common ad-hoc communicative objects where a small cost is used to signal avoidance. Using computational modeling, we first show that goal inference from indirect physical evidence can give rise to the ability to use object placement to communicate. We then show that people from the U.S. and the Tsimane'-a farming-foraging group native to the Bolivian Amazon-can infer the communicative meaning of object placement in the absence of a pre-existing convention, and that people's inferences are quantitatively predicted by our model. Finally, we show evidence that people can store and retrieve this meaning for use in subsequent encounters, revealing a potential mechanism for how ad-hoc communicative objects become quickly conventionalized. Our model helps shed light on how humans use their ability to interpret other people's behavior to embed social meaning into the physical world.

Intention beyond desire: Spontaneous intentional commitment regulates conflicting desires

The human mind is a mosaic composed of multiple selves with conflicting desires. How can coherent actions emerge from such conflicts? Classical desire theory argues that rational action depends on maximizing the expected utilities evaluated by all desires. In contrast, intention theory suggests that humans regulate conflicting desires with an intentional commitment that constrains action planning towards a fixed goal. Here, we designed a series of 2D navigation games in which participants were instructed to navigate to two equally desirable destinations. We focused on the critical moments in navigation to test whether humans spontaneously commit to an intention and take actions that would be qualitatively different from those of a purely desire-driven agent. Across four experiments, we found three distinctive signatures of intentional commitment that only exist in human actions: "goal perseverance" as the persistent pursuit of an original intention despite unexpected drift making the intention suboptimal; "self-binding" as the proactive binding of oneself to a committed future by avoiding a path that could lead to many futures; and "temporal leap" as the commitment to a distant future even before reaching the proximal one. These results suggest that humans spontaneously form an intention with a committed plan to quarantine conflicting desires from actions, supporting intention as a distinctive mental state beyond desire. Additionally, our findings shed light on the possible functions of intention, such as reducing computational load and making one's actions more predictable in the eyes of a third-party observer.

Peekbank: An open, large-scale repository for developmental eye-tracking data of children's word recognition

The ability to rapidly recognize words and link them to referents is central to children's early language development. This ability, often called word recognition in the developmental literature, is typically studied in the looking-while-listening paradigm, which measures infants' fixation on a target object (vs. a distractor) after hearing a target label. We present a large-scale, open database of infant and toddler eye-tracking data from looking-while-listening tasks. The goal of this effort is to address theoretical and methodological challenges in measuring vocabulary development. We first present how we created the database, its features and structure, and associated tools for processing and accessing infant eye-tracking datasets. Using these tools, we then work through two illustrative examples to show how researchers can use Peekbank to interrogate theoretical and methodological questions about children's developing word recognition ability.

Not Playing by the Rules: Exploratory Play, Rational Action, and Efficient Search

Recent studies suggest children's exploratory play is consistent with formal accounts of rational learning. Here we focus on the tension between this view and a nearly ubiquitous feature of human play: In play, people subvert normal utility functions, incurring seemingly unnecessary costs to achieve arbitrary rewards. We show that four-and-five-year-old children not only infer playful behavior from observed violations of rational action (Experiment 1), but themselves take on unnecessary costs during both retrieval (Experiment 2) and search (Experiments 3A-B) tasks, despite acting efficiently in non-playful, instrumental contexts. We discuss the value of such apparently utility-violating behavior and why it might serve learning in the long run.

Précis of What Babies Know

Where does human knowledge begin? Research on human infants, children, adults, and nonhuman animals, using diverse methods from the cognitive, brain, and computational sciences, provides evidence for six early emerging, domain-specific systems of core knowledge. These automatic, unconscious systems are situated between perceptual systems and systems of explicit concepts and beliefs. They emerge early in infancy, guide children's learning, and function throughout life.

Having less means wanting more: Children hold an intuitive economic theory of diminishing marginal utility

Judgments surrounding resource acquisition and valuation are ubiquitous in daily life. How do humans decide what something is worth to themselves or someone else? One important cue to value is that of resource quantity. As described by economists, the principle of diminishing marginal utility (DMU) holds that as resource abundance increases, the value placed on each unit decreases; likewise, when resources become more scarce, the value placed on each unit rises. While prior research suggests that adults make judgments that align with this concept, it is unclear whether children do so. In Study 1 (n = 104), children (ages 5 through 8) were presented with scenarios involving losses or gains to others' resources and predicted the actions and emotions of the individuals involved. Participants made decisions that aligned with DMU, e.g., expecting individuals with fewer resources to expend more effort for an additional resource than individuals with greater resources. In Study 2 (n = 104), children incorporated information about preferences when inferring others' resource valuations, showing how quantity and preference are both included in children's inferences about others' utility. Our results indicate the early emergence of an intuitive economic theory that aligns with an important economic principle. Long before formal learning on this topic, children integrate quantity and preference information to sensibly predict others' resource valuations, with implications for economic decision-making, social preferences, and judgments of partner quality across the lifespan.

Preference matters: Knowledge of beneficiary's preference influences children's evaluations of the act of leaving a choice for others

People value indirect prosocial actions that benefit others as byproducts of self-oriented actions. One example of such an action is the act of leaving a choice for others when selecting an item for oneself. In this study, we investigated how knowledge of the beneficiary's preference may influence children's evaluations of such actions. Children (n = 91, 4- to 10-year-olds) and adults (n = 43) were asked to evaluate characters taking a snack for themselves from a set of three items-two identical items and one unique item-in a way that either leaves a choice (two different items) or leaves no choice (two identical items) for the next person (the beneficiary). The beneficiary's preference was systematically manipulated as unknown, preferring the unique item, or preferring the item of which there are two. We found notable developmental changes: Children as young as 4 years of age understand that it is nicer not to take away the only thing others prefer; with age, children increasingly appreciate the value of leaving a diverse choice when the beneficiary's preference is unknown; however, when the beneficiary clearly prefers the item of which there are two, children increasingly think that it is nicer to leave two identical but preferred items than to leave a diverse choice. These findings reveal increasing flexibility and subtlety in children's social evaluation of indirect prosocial actions; their evaluation develops from a mere understanding of the value of preference to a flexible appreciation of both preference and choice.

Interpersonal utility and children's social inferences from shared preferences

Similarity of behaviors or attributes is often used to infer social affiliation and prosociality. Does this reflect reasoning using a simple expectation of homophily, or more complex reasoning about shared utility? We addressed this question by examining the inferences children make from similar choices when this similarity does or does not cause competition over a zero-sum resource. Four- to six-year-olds (N = 204) saw two vignettes, each featuring three characters (a target plus two others) choosing between two types of resources. In all stories, each character expressed a preference: one 'other' chose the same resource as the target, while a second 'other' chose the different resource. In one condition there were enough resources for all the characters; in the other condition, one type of resource was limited, with only one available (inducing potential competition between the target and the similar-choice other). Children then judged which of the two 'other' characters was being nicer (prosocial judgment) and which of the two was more preferred by the target (affiliative inference). When resources were limited (vs. unlimited), children were less likely to select the similar other as being nice. Children's initial tendency to report that the target preferred the similar other was also eliminated in the limited resource scenario. These findings show that children's reasoning about similarity is not wholly based on homophily. Instead, by reasoning about shared utility - how each person values the goals of others - children engage in flexible inferences regarding whether others' similar preferences and behaviors have positive or negative social meaning.

Commonsense psychology in human infants and machines

Human infants are fascinated by other people. They bring to this fascination a constellation of rich and flexible expectations about the intentions motivating people's actions. Here we test 11-month-old infants and state-of-the-art learning-driven neural-network models on the "Baby Intuitions Benchmark (BIB)," a suite of tasks challenging both infants and machines to make high-level predictions about the underlying causes of agents' actions. Infants expected agents' actions to be directed towards objects, not locations, and infants demonstrated default expectations about agents' rationally efficient actions towards goals. The neural-network models failed to capture infants' knowledge. Our work provides a comprehensive framework in which to characterize infants' commonsense psychology and takes the first step in testing whether human knowledge and human-like artificial intelligence can be built from the foundations cognitive and developmental theories postulate.

Rational information search in welfare-tradeoff cognition

One of the most important dimensions along which we evaluate others is their propensity to value our welfare: we like people who are disposed to incur costs for our benefit and who refrain from imposing costs on us to benefit themselves. The evolutionary importance of social valuation in our species suggests that humans have cognitive mechanisms that are able to efficiently extract information about how much another person values them. Here I test the hypothesis that people are spontaneously interested in the kinds of events that have the most potential to reveal such information. In two studies, I presented participants (Ns = 216; 300) with pairs of dilemmas that another individual faced in an economic game; for each pair, I asked them to choose the dilemma for which they would most like to see the decision that the individual had made. On average, people spontaneously selected the choices that had the potential to reveal the most information about the individual's valuation of the participant, as quantified by a Bayesian ideal search model. This finding suggests that human cooperation is supported by sophisticated cognitive mechanisms for information-gathering.

Understanding preferences in infancy

A preference is defined as a dispositional state that helps explain why a person chooses one option over another. Preference understanding is a significant part of interpreting and predicting others' behavior, which can also help to guide social encounters, for instance, to initiate interactions and even form relationships based on shared preferences. Cognitive developmental research in the past several decades has revealed that infants have relatively sophisticated understandings about others' preferences, as part of investigations into how young children make sense of others' behavior in terms of mental states such as intentions, dispositions including preferences, and epistemic states. In recent years, research on early psychological knowledge expands to including infant understanding of social situations. As such, infants are also found to use their preference understandings in their social life. They treat favorably others who share their own preferences, and they prefer prosocial and similar others (e.g., those who speak their language). In reviewing these results, we point out future directions for research and conclude with further suggestions and recommendations. This article is categorized under: Cognitive Biology > Cognitive Development Psychology > Development and Aging.

Should I learn from you? Seeing expectancy violations about action efficiency hinders social learning in infancy

Infants generate basic expectations about their physical and social environment. This early knowledge allows them to identify opportunities for learning, preferring to explore and learn about objects that violate their prior expectations. However, less is known about how expectancy violations about people's actions influence infants' subsequent learning from others and about others. Here, we presented 18-month-old infants with an agent who acted either efficiently (expected action) or inefficiently (unexpected action) and then labeled an object. We hypothesized that infants would prefer to learn from the agent (label-object association) if she previously acted efficiently, but they would prefer to learn about the agent (voice-speaker association) if she previously acted inefficiently. As expected, infants who previously saw the agent acting efficiently showed greater attention to the demonstrated object and learned the new label-object association, but infants presented with the inefficient agent did not. However, there was no evidence that infants learned the voice-speaker association in any of the conditions. In summary, expectancy violations about people's actions may signal a situation to avoid learning from them. We discussed the results in relation to studies on surprise-induced learning, motionese, and selective social learning, and we proposed other experimental paradigms to investigate how expectancy violations influence infants' learning about others.

When it's not easy to do the right thing: Developmental changes in understanding cost drive evaluations of moral praiseworthiness

Recent work identified a shift in judgments of moral praiseworthiness that occurs late in development: adults recognize the virtue of moral actions that involve resolving an inner conflict between moral desires and selfish desires. Children, in contrast, praise agents who do the right thing in the absence of inner conflict. This finding stands in contrast with other work showing that children incorporate notions of cost and effort into their social reasoning. Using a modified version of Starmans and Bloom's (2016) vignettes, we show that understanding the virtue of costly moral action precedes understanding the virtue of resolving inner conflict. In two studies (N = 192 children, range = 4.00-9.95 years; and N = 193 adults), we contrasted a character who paid a personal cost (psychological in Study 1, physical in Study 2) to perform a moral action with another who acted morally without paying a cost. We found a developmental progression; 8- and 9-year-old children and adults recognized the praiseworthiness of moral actions that are psychologically or physically costly. Six- and 7-year-old children only recognized the praiseworthiness of moral actions that are physically costly, but not actions that are psychologically costly. Moreover, neither adults nor children inferred that paying a cost to act morally required having a moral desire or resolving inner conflict. These results suggest that both adults and children conceptualize obligation as a direct motivational force on actions. They further suggest that costly choice-a hallmark of moral agency-is implicated in judgments of praiseworthiness early in development.

Dangerous Ground: One-Year-Old Infants are Sensitive to Peril in Other Agents' Action Plans

Do infants appreciate that other people's actions may fail, and that these failures endow risky actions with varying degrees of negative utility (i.e., danger)? Three experiments, including a pre-registered replication, addressed this question by presenting 12- to 15-month-old infants (N = 104, 52 female, majority White) with an animated agent who jumped over trenches of varying depth towards its goals. Infants expected the agent to minimize the danger of its actions, and they learned which goal the agent preferred by observing how much danger it risked to reach each goal, even though the agent's actions were physically identical and never failed. When we tested younger, 10-month-old infants (N = 102, 52 female, majority White) in a fourth experiment, they did not succeed consistently on the same tasks. These findings provide evidence that one-year-old infants use the height that other agents could fall from in order to explain and predict those agents' actions.

Infants expect agents to minimize the collective cost of collaborative actions

This paper argues that human infants address the challenges of optimizing, recognizing, and interpreting collaborative behaviors by assessing their collective efficiency. This hypothesis was tested by using a looking-time study. Fourteen-month-olds (N = 32) were familiarized with agents performing a collaborative action in computer animations. During the test phase, the looking times were measured while the agents acted with various efficiency parameters. In the critical condition, the agents' actions were individually efficient, but their combination was either collectively efficient or inefficient. Infants looked longer at test events that violated expectations of collective efficiency (p = .006, d = 0.79). Thus, preverbal infants apply expectations of collective efficiency to actions involving multiple agents.

People infer communicative action through an expectation for efficient communication

Humans often communicate using body movements like winks, waves, and nods. However, it is unclear how we identify when someone’s physical actions are communicative. Given people’s propensity to interpret each other’s behavior as aimed to produce changes in the world, we hypothesize that people expect communicative actions to efficiently reveal that they lack an external goal. Using computational models of goal inference, we predict that movements that are unlikely to be produced when acting towards the world and, in particular, repetitive ought to be seen as communicative. We find support for our account across a variety of paradigms, including graded acceptability tasks, forced-choice tasks, indirect prompts, and open-ended explanation tasks, in both market-integrated and non-market-integrated communities. Our work shows that the recognition of communicative action is grounded in an inferential process that stems from fundamental computations shared across different forms of action interpretation.

Humans can quickly infer when someone’s body movements are meant to be communicative. Here, the authors show that this capacity is underpinned by an expectation that communicative actions will efficiently reveal that they lack an external goal.

What Could Go Wrong: Adults and Children Calibrate Predictions and Explanations of Others' Actions Based on Relative Reward and Danger

When human adults make decisions (e.g., wearing a seat belt), we often consider the negative consequences that would ensue if our actions were to fail, even if we have never experienced such a failure. Do the same considerations guide our understanding of other people's decisions? In this paper, we investigated whether adults, who have many years of experience making such decisions, and 6- and 7-year-old children, who have less experience and are demonstrably worse at judging the consequences of their own actions, conceive others' actions as motivated both by reward (how good reaching one's intended goal would be), and by what we call "danger" (how badly one's action could end). In two pre-registered experiments, we tested whether adults and 6- and 7-year-old children tailor their predictions and explanations of an agent's action choices to the specific degree of danger and reward entailed by each action. Across four different tasks, we found that children and adults expected others to negatively appraise dangerous situations and minimize the danger of their actions. Children's and adults' judgments varied systematically in accord with both the degree of danger the agent faced and the value the agent placed on the goal state it aimed to achieve. However, children did not calibrate their inferences about how much an agent valued the goal state of a successful action in accord with the degree of danger the action entailed, and adults calibrated these inferences more weakly than inferences concerning the agent's future action choices. These results suggest that from childhood, people use a degree of danger and reward to make quantitative, fine-grained explanations and predictions about other people's behavior, consistent with computational models on theory of mind that contain continuous representations of other agents' action plans.

Easy or difficult? Children's understanding of how supply and demand affect goal completion

Three experiments examined children's understanding of how supply and demand affect the difficulty of completing goals. Participants were 368 predominantly White Canadians (52% female, 48% male) tested in 2017-2022. In Experiment 1, 3-year-olds recognized that obtaining resources is easier where supply exceeds demand than where demand exceeds supply. However, in Experiment 2, 3-year-olds were insensitive to supply and demand when comparing situations where demand exceeded supply to a greater or lesser degree. Finally, Experiment 3 revealed a developmental lag in 3- to 7-year-olds' understanding of how supply and demand affects goal completion: Children succeeded when contrasting a surplus and a shortage of supply relative to demand at 4;2. But they only succeeded when contrasting degrees of greater supply than demand at 5;10.

Adopted Utility Calculus: Origins of a Concept of Social Affiliation

To successfully navigate their social world, humans need to understand and map enduring relationships between people: Humans need a concept of social affiliation. Here I propose that the initial concept of social affiliation, available in infancy, is based on the extent to which one individual consistently takes on the goals and needs of another. This proposal grounds affiliation in intuitive psychology, as formalized in the naive-utility-calculus model. A concept of affiliation based on interpersonal utility adoption can account for findings from studies of infants' reasoning about imitation, similarity, helpful and fair individuals, "ritual" behaviors, and social groups without the need for additional innate mechanisms such as a coalitional psychology, moral sense, or general preference for similar others. I identify further tests of this proposal and also discuss how it is likely to be relevant to social reasoning and learning across the life span.

Human adults prefer to cooperate even when it is costly

Joint actions are cooperative activities where humans coordinate their actions to achieve individual and shared goals. While the motivation to engage in joint action is clear when a goal cannot be achieved by individuals alone, we asked whether humans are motivated to act together even when acting together is not necessary and implies incurring additional costs compared to individual goal achievement. Using a utility-based empirical approach, we investigated the extent of humans' preference for joint action over individual action, when the instrumental costs of performing joint actions outweigh the benefits. The results of five experiments showed that human adults have a stable preference for joint action, even if individual action is more effective to achieve a certain goal. We propose that such preferences can be understood as ascribing additional reward value to performing actions together.

Precise functional connections between the dorsal anterior cingulate cortex and areas recruited for physical inference

Recent work has identified brain areas that are engaged when people predict how the physical behavior of the world will unfold - an ability termed intuitive physics. Among the many unanswered questions about the neural mechanisms of intuitive physics is where the key inputs come from: which brain regions connect up with intuitive physics processes to regulate when and how they are engaged in service of our goals? In the present work, we targeted the dorsal anterior cingulate cortex (dACC) for study based on characteristics that make it well-positioned to regulate intuitive physics processes. The dACC is richly interconnected with frontoparietal regions and is implicated in mapping contexts to actions, a process that would benefit from physical predictions to indicate which action(s) would produce the desired physical outcomes. We collected resting state functional MRI data in seventeen participants and used independent task-related runs to find the pattern of activity during a physical inference task in each individual participant. We found that the strongest resting state functional connections of the dACC not only aligned well with physical inference-related activity at the group level, it also mirrored individual differences in the positioning of physics-related activity across participants. Our results suggest that the dACC might be a key structure for regulating the engagement of intuitive physics processes in the brain.

Latent motives guide structure learning during adaptive social choice

Predicting the behaviour of others is an essential part of social cognition. Despite its ubiquity, social prediction poses a poorly understood generalization problem: we cannot assume that others will repeat past behaviour in new settings or that their future actions are entirely unrelated to the past. We demonstrate that humans solve this challenge using a structure learning mechanism that uncovers other people's latent, unobservable motives, such as greed and risk aversion. In four studies, participants (N = 501) predicted other players' decisions across four economic games, each with different social tensions (for example, Prisoner's Dilemma and Stag Hunt). Participants achieved accurate social prediction by learning the stable motivational structure underlying a player's changing actions across games. This motive-based abstraction enabled participants to attend to information diagnostic of the player's next move and disregard irrelevant contextual cues. Participants who successfully learned another's motives were more strategic in a subsequent competitive interaction with that player in entirely new contexts, reflecting that social structure learning supports adaptive social behaviour.