Rebecca A. Williamson

Prior Experiences and Perceived Efficacy Influence 3-Year-Olds’ Imitation

Children are selective and flexible imitators. They combine their own prior experiences and the perceived causal efficacy of the model to determine whether and what to imitate. In Experiment 1, children were randomly assigned to have either a difficult or an easy experience achieving a goal. They then saw an adult use novel means to achieve the goal. Children with a difficult prior experience were more likely to imitate the adults precise means. Experiment 2 showed further selectivity--children preferentially imitated causally efficacious versus nonefficacious acts. In Experiment 3, even after an easy prior experience led children to think their own means would be effective, they still encoded the novel means performed by the model. When a subsequent manipulation rendered the childrens means ineffective, children recalled and imitated the models means. The research shows that children integrate information from their own prior interventions and their observations of others to guide their imitation.

Chimpanzees play the ultimatum game

Is the sense of fairness uniquely human? Human reactions to reward division are often studied by means of the ultimatum game, in which both partners need to agree on a distribution for both to receive rewards. Humans typically offer generous portions of the reward to their partner, a tendency our close primate relatives have thus far failed to show in experiments. Here we tested chimpanzees (Pan troglodytes) and human children on a modified ultimatum game. One individual chose between two tokens that, with their partner’s cooperation, could be exchanged for rewards. One token offered equal rewards to both players, whereas the other token favored the chooser. Both apes and children responded like humans typically do. If their partner’s cooperation was required, they split the rewards equally. However, with passive partners—a situation akin to the so-called dictator game—they preferred the selfish option. Thus, humans and chimpanzees show similar preferences regarding reward division, suggesting a long evolutionary history to the human sense of fairness.

Learning the Rules: Observation and Imitation of a Sorting Strategy by 36-Month-Old Children

Two experiments were used to investigate the scope of imitation by testing whether 36-month-olds can learn to produce a categorization strategy through observation. After witnessing an adult sort a set of objects by a visible property (their color; Experiment 1) or a nonvisible property (the particular sounds produced when the objects were shaken; Experiment 2), children showed significantly more sorting by those dimensions relative to children in control groups, including a control in which children saw the sorted endstate but not the intentional sorting demonstration. The results show that 36-month-olds can do more than imitate the literal behaviors they see; they also abstract and imitate rules that they see another person use.

Imitation as a mechanism in cognitive development: a cross-cultural investigation of 4-year-old children’s rule learning

Children learn about the social and physical world by observing other people’s acts. This experiment tests both Chinese and American children’s learning of a rule. For theoretical reasons we chose the rule of categorizing objects by the weight. Children, age 4 years, saw an adult heft four visually-identical objects and sort them into two bins based on an invisible property—the object’s weight. Children who saw this categorization behavior were more likely to sort those objects by weight than were children who saw control actions using the same objects and the same bins. Crucially, children also generalized to a novel set of objects with no further demonstration, suggesting rule learning. We also report that high-fidelity imitation of the adult’s “hefting” acts may give children crucial experience with the objects’ weights, which could then be used to infer the more abstract rule. The connection of perception, action, and cognition was found in children from both cultures, which leads to broad implications for how the imitation of adults’ acts functions as a lever in cognitive development.

Prospective memory in children and chimpanzees.

Prospective memory (PM) involves remembering to do something at a specific time in the future. Here, we investigate the beginnings of this ability in young children (3-year-olds; Homo sapiens) and chimpanzees (Pan troglodytes) using an analogous task. Subjects were given a choice between two toys (children) or two food items (chimpanzees). The selected item was delivered immediately, whereas the unselected item was hidden in an opaque container. After completing an ongoing quantity discrimination task, subjects could request the hidden item by asking for it (children) or by pointing to the container and identifying the item on a symbol board (chimpanzees). Children and chimpanzees showed evidence of prospective-like memory in this task, as evidenced by successful retrieval of the item at the end of the task, sometimes spontaneously with no prompting from the experimenter. These findings contribute to our understanding of PM from an ontogenetic and comparative perspective.

Learning How to Help Others: Two-Year-Olds' Social Learning of a Prosocial Act.

Engaging in prosocial behaviors (acts that benefit others) is associated with many positive outcomes in children, including the development of positive peer relationships, academic achievement, and good psychological functioning. This study examined the social learning mechanisms toddlers use to acquire prosocial behaviors. This brief report presents a new experimental procedure in which 2-year-olds (28-32 months, N=30) saw a video of an adult performing a novel prosocial behavior in response to another persons distress. Children then had the opportunity to imitate and implement the behavior in response to their own parents physical distress. Children who saw the video were more likely to perform the novel action and to display non-demonstrated prosocial behaviors relative to (a) children who did not view the video but saw a parent in distress and (b) children who saw the video but witnessed their mother engage in a neutral activity. These results suggest that toddlers imitate and emulate prosocial behaviors for social interaction and that children can apply such behaviors in appropriate situations.

Gambling primates: reactions to a modified Iowa Gambling Task in humans, chimpanzees and capuchin monkeys

Humans will, at times, act against their own economic self-interest, for example, in gambling situations. To explore the evolutionary roots of this behavior, we modified a traditional human gambling task, the Iowa Gambling Task (IGT), for use with chimpanzees, capuchin monkeys and humans. We expanded the traditional task to include two additional payoff structures to fully elucidate the ways in which these primate species respond to differing reward distributions versus overall quantities of rewards, a component often missing in the existing literature. We found that while all three species respond as typical humans do in the standard IGT payoff structure, species and individual differences emerge in our new payoff structures. Specifically, when variance avoidance and reward maximization conflicted, roughly equivalent numbers of apes maximized their rewards and avoided variance, indicating that the traditional payoff structure of the IGT is insufficient to disentangle these competing strategies. Capuchin monkeys showed little consistency in their choices. To determine whether this was a true species difference or an effect of task presentation, we replicated the experiment but increased the intertrial interval. In this case, several capuchin monkeys followed a reward maximization strategy, while chimpanzees retained the same strategy they had used previously. This suggests that individual differences in strategies for interacting with variance and reward maximization are present in apes, but not in capuchin monkeys. The primate gambling task presented here is a useful methodology for disentangling strategies of variance avoidance and reward maximization.

Brief Report: Imitation of Object-Directed Acts in Young Children with Autism Spectrum Disorders

Abstract Children with autism spectrum disorders (ASD) imitate less than typically developing (TD) children; however, the specific features and causes of this deficit are still unclear. The current study investigates the role of joint engagement, specifically children’s visual attention to demonstrations, in an object-directed imitation task. This sample was recruited from an early ASD screening study, which allows for an examination of these behaviors prior to formal diagnosis and ASD-specific intervention. Children with ASD imitated less than TD children; children with other developmental delays showed no significant difference from the two other screen-positive groups. Additionally, only the ASD group showed decreased visual attention, suggesting that early visual attention plays a role in the social learning of children with ASD.

Reply to Jensen et al.: Equitable offers are not rationally maximizing

When playing the ultimatum game, chimpanzees and children shifted their behavior from selfish offers in the preference test to more equitable ones in the ultimatum game (1). Why did they do so? All that we can measure is behavior, not motivations. Nonetheless, in human studies equitable outcomes are interpreted as reflecting a sense of fairness, thus this explanation must be considered for the apes as well. Given the genetic similarity between both species, shared explanations are the most parsimonious from an evolutionary perspective. Indeed, Jensen et al. (2) offer no alternative and ignored the similar responses of the children in our study.

Type of iconicity influences children’s comprehension of gesture

Children produce iconic gestures conveying action information earlier than the ones conveying attribute information (Özçalışkan, Gentner, & Goldin-Meadow, 2014). In this study, we ask whether childrens comprehension of iconic gestures follows a similar pattern, also with earlier comprehension of iconic gestures conveying action. Children, ages 2-4years, were presented with 12 minimally-informative speech+iconic gesture combinations, conveying either an action (e.g., open palm flapping as if bird flying) or an attribute (e.g., fingers spread as if birds wings) associated with a referent. They were asked to choose the correct match for each gesture in a forced-choice task. Our results showed that children could identify the referent of an iconic gesture conveying characteristic action earlier (age 2) than the referent of an iconic gesture conveying characteristic attribute (age 3). Overall, our study identifies ages 2-3 as important in the development of comprehension of iconic co-speech gestures, and indicates that the comprehension of iconic gestures with action meanings is easier than, and may even precede, the comprehension of iconic gestures with attribute meanings.