Karen Wynn

Social evaluation by preverbal infants

The capacity to evaluate other people is essential for navigating the social world. Humans must be able to assess the actions and intentions of the people around them, and make accurate decisions about who is friend and who is foe, who is an appropriate social partner and who is not. Indeed, all social animals benefit from the capacity to identify individual conspecifics that may help them, and to distinguish these individuals from others that may harm them. Human adults evaluate people rapidly and automatically on the basis of both behaviour and physical features, but the ontogenetic origins and development of this capacity are not well understood. Here we show that 6- and 10-month-old infants take into account an individual’s actions towards others in evaluating that individual as appealing or aversive: infants prefer an individual who helps another to one who hinders another, prefer a helping individual to a neutral individual, and prefer a neutral individual to a hindering individual. These findings constitute evidence that preverbal infants assess individuals on the basis of their behaviour towards others. This capacity may serve as the foundation for moral thought and action, and its early developmental emergence supports the view that social evaluation is a biological adaptation.

Children's Acquisition of the Number Words and the Counting System

This paper examines how and when children come to understand the way in which counting determines numerosity and learn the meanings of the number words. A 7-month longitudinal study of 2 and 3 year olds shows that, very early on, children already know that the counting words each refer to a distinct, unique numerosity, though they do not yet know to which numerosity each word refers. It is possible that children learn this in part from the syntax of the number words. Despite this early knowledge, however, it takes children a long time (on the order of a year) to learn how the counting system represents numerosity. This suggests that our initial concept of number is represented quite differently from the way the counting system represents number, making it a difficult task for children to map the one Onto the Other.

Attribution of Dispositional States by 12-Month-Olds

The ability to interpret the behavior of other individuals is essential for effective social functioning. Many investigators now believe that even young infants can recognize that agents act toward goals. Here we report three experiments suggesting that 12-month-old infants not only can recognize goal-related action, but also can interpret future actions of an actor on the basis of previously witnessed behavior in another context. The possibility that this inference is made through the attribution of mental states is discussed.

Three-Month-Olds Show a Negativity Bias in Their Social Evaluations.

Previous research has shown that 6-month-olds evaluate others on the basis of their social behaviors--they are attracted to prosocial individuals, and avoid antisocial individuals (Hamlin, Wynn & Bloom, 2007). The current studies investigate these capacities prior to 6 months of age. Results from two experiments indicate that even 3-month-old infants evaluate others based on their social behavior towards third parties, and that negative social information is developmentally privileged.

Psychological foundations of number: numerical competence in human infants

An enduring question in philosophy and psychology is that of how we come to possess knowledge of number. Here I review research suggesting that the capacity to represent and reason about number is part of the inherent structure of the human mind. In the first few months of life, human infants can enumerate sets of entities and perform numerical computations. One proposal is that these abilities arise from general cognitive capacities not specific to number. I argue that the body of data supports a very different proposal: humans possess a specialized mental mechanism for number, one which we share with other species and which has evolved through natural selection. This mechanism is inherently restricted in the kinds of numerical knowledge it can support, leading to some striking limitations to early competence.

How infants and toddlers react to antisocial others

Although adults generally prefer helpful behaviors and those who perform them, there are situations (in particular, when the target of an action is disliked) in which overt antisocial acts are seen as appropriate, and those who perform them are viewed positively. The current studies explore the developmental origins of this capacity for selective social evaluation. We find that although 5-mo-old infants uniformly prefer individuals who act positively toward others regardless of the status of the target, 8-mo-old infants selectively prefer characters who act positively toward prosocial individuals and characters who act negatively toward antisocial individuals. Additionally, young toddlers direct positive behaviors toward prosocial others and negative behaviors toward antisocial others. These findings constitute evidence that the nuanced social judgments and actions readily observable in human adults have their foundations in early developing cognitive mechanisms.

Enumeration of collective entities by 5-month-old infants

Recent findings suggest that infants are capable of distinguishing between different numbers of objects, and of performing simple arithmetical operations. But there is debate over whether these abilities result from capacities dedicated to numerical cognition, or whether infants succeed in such experiments through more general, non-numerical capacities, such as sensitivity to perceptual features or mechanisms of object tracking. We report here a study showing that 5-month-olds can determine the number of collective entities -- moving groups of items -- when non-numerical perceptual factors such as contour length, area, density, and others are strictly controlled. This suggests both that infants can represent number per se, and that their grasp of number is not limited to the domain of objects.

Ratio Abstraction by 6-Month-Old Infants

Human infants appear to be capable of the rudimentary mathematical operations of addition, subtraction, and ordering. To determine whether infants are capable of extracting ratios, we presented 6-month-old infants with multiple examples of a single ratio. After repeated presentations of this ratio, the infants were presented with new examples of a new ratio, as well as new examples of the previously habituated ratio. Infants were able to successfully discriminate two ratios that differed by a factor of 2, but failed to detect the difference between two numerical ratios that differed by a factor of 1.5. We conclude that infants can extract a common ratio across test scenes and use this information while examining new displays. The results support an approximate magnitude-estimation system, which has also been found in animals and human adults.

Social Evaluation by Preverbal Infants

Adult humans’ successful existence in the social world rests on the ability to evaluate others. We must be able to determine the trustworthy from the untrustworthy individuals, and identify who is likely to be helpful, who is not—who might be worth approaching and who it is better to avoid. These judgments are informed in part by others’ behaviors—we tend to judge positively those whose actions toward others are prosocial and helpful, and to judge negatively those whose actions are harmful or antisocial in nature. By assuming that others’ social actions are motivated by underlying and enduring personality traits that will continue to influence their behavior over time, we can make judgments about who will be a good or bad social partner. When and how does the ability to evaluate others develop? Is it something that we learn during childhood by observing and experiencing the explicit judgments, approbations, and condemnations of our parents and others, or are the seeds of an evaluative capacity present before the onset of language and explicit teaching? Recent research with infants in the first year of life suggests the latter (1). In these studies, 6and 10-mo-old infants were presented with a puppet show in which a character tried, but repeatedly failed on its own, to reach the top of a steep hill. On alternating attempts, the climber was helped up the hill by a second puppet, and hindered—pushed down the hill—by a third puppet. Infants were shown these events repeatedly until they lost interest in the displays (indicated by decreased looking to the events). Each infant was then offered a choice between the helping and hindering characters. The large majority of both 6and 10-mo-old infants chose the helper—presumably because it had helped the climber achieve its goal. This interpretation was supported by an additional study in which infants chose between two characters, which pushed an inanimate object, either to the top or the bottom of the hill. In this study, babies showed no preference between the two characters, suggesting that infants’ choices in the first study were not based on physical aspects of the displays (such as a general preference for those that push up). Together, these results suggest that even infants evaluate individuals based on their behavior toward others: infants prefer those who help others to those who hinder them. Do infants’ choices for the helping over the hindering character reflect a preference for the helper, an aversion for the hinderer, or both? In a third study, infants of both ages reliably preferred a helping character to a neutral one (who did not interact with the climber), and a neutral character to a hindering one, indicating that infants both positively evaluate individuals who aid others and negatively evaluate individuals who impede others. This research indicates that even very young infants evaluate others based on their behavior, long before they have been explicitly taught to do so. Further research will investigate the extents and limits of infants’ evaluative system, and how this basic system, with time and experience, develops into the mature and nuanced system of moral evaluation present in adults. – J. Kiley Hamlin, Karen Wynn, Paul Bloom

Not like me = bad: Infants prefer those who harm dissimilar others

Adults tend to like individuals who are similar to themselves, and a growing body of recent research suggests that even infants and young children prefer individuals who share their attributes or personal tastes over those who do not. In this study, we examined the nature and development of attitudes toward similar and dissimilar others in human infancy. Across two experiments with combined samples of more than 200 infant participants, we found that 9- and 14-month-old infants prefer individuals who treat similar others well and treat dissimilar others poorly. A developmental trend was observed, such that 14-month-olds’ responses were more robust than were 9-month-olds’. These findings suggest that the identification of common and contrasting personal attributes influences social attitudes and judgments in powerful ways, even very early in life.