An object's categorizability impacts whether infants encode surface features into their object representations.

Infants encode the surface features of simple, unfamiliar objects (e.g., red triangle) and the categorical identities of familiar, categorizable objects (e.g., car) into their representations of these objects. We asked whether 16-18-month-olds ignore non-diagnostic surface features (e.g., color) in favor of encoding an object's categorical identity (e.g., car) when objects are from familiar categories. In Experiment 1 (n = 18), we hid a categorizable object inside an opaque box. In No Switch trials, infants retrieved the object that was hidden. In Switch trials, infants retrieved a different object: an object from a different category (Between-Category-Switch trials) or a different object from the same category (Within-Category-Switch trials). We measured infants' subsequent searching in the box. Infants' pattern of searching suggested that only infants who completed a Within-Category-Switch trial as their first Switch trial encoded objects' surface features, and an exploratory analysis suggested that infants who completed a Between-Category-Switch trial as their first Switch trial only encoded objects' categories. In Experiment 2 (n = 18), we confirmed that these results were due to objects' categorizability. These results suggest infants may tailor the way they encode categorizable objects depending on which object dimensions are perceived to be task relevant.

Infants preferentially learn from surprising teachers.

Infants have sophisticated knowledge about the physical world, and show enhanced learning about objects that violate physical principles. However, it is unknown whether infants also preferentially learn from the individual who produces an outcome that violates expectations. We investigated whether 15-month-old infants (N = 48) selectively imitate individuals who produce surprising outcomes. In Experiment 1, infants watched an experimenter hide a ball and produce an expected outcome in which the ball was revealed where it was hidden, or a surprising outcome in which the ball was revealed in a different location. The experimenter then demonstrated a novel action: using her head to activate a light while her hands were free. Infants imitated that novel action more if the experimenter had previously produced a surprising than an expected outcome. In Experiment 2, infants witnessed the experimenter produce the surprising outcome, then use her head to activate the light while her hands were occupied. Infants did not differentially imitate the head-touch action relative to either condition in Experiment 1, perhaps indicating a tension between surprise-induced learning and rational imitation. These experiments show that surprising events are pedagogical opportunities: infants selectively learn from surprising individuals, but also may account for rationality in their surprise-induced social learning.

When Not Choosing Leads to Not Liking: Choice-Induced Preference in Infancy.

The question of how people's preferences are shaped by their choices has generated decades of research. In a classic example, work on cognitive dissonance has found that observers who must choose between two equally attractive options subsequently avoid the unchosen option, suggesting that not choosing the item led them to like it less. However, almost all of the research on such choice-induced preference focuses on adults, leaving open the question of how much experience is necessary for its emergence. Here, we examined the developmental roots of this phenomenon in preverbal infants (N = 189). In a series of seven experiments using a free-choice paradigm, we found that infants experienced choice-induced preference change similar to adults'. Infants' choice patterns reflected genuine preference change and not attraction to novelty or inherent attitudes toward the options. Hence, choice shapes preferences-even without extensive experience making decisions and without a well-developed self-concept.

Infants use linguistic group distinctions to chunk items in memory.

Although the capacity of infants' working memory is highly constrained, infants can overcome this limit via chunking; for example, they can use spatial cues to group individual objects into sets, thereby increasing memory efficiency. Here we investigated the use of abstract social knowledge as a basis for chunking. In four experiments, we asked whether 16-month-olds can use their sensitivity to distinctions between languages to efficiently chunk an array. Infants saw four identical dolls hidden in a box. Without chunking cues, infants in previous experiments fail to remember this number of items in such arrays. In Experiment 1, infants saw two of the four dolls each produce an utterance in a familiar language (English) prior to hiding and saw the other two dolls each produce an unfamiliar language (German or Mandarin). Infants successfully remembered all four dolls. Next we asked whether infants could chunk using linguistic group distinctions even when all dolls spoke unfamiliar languages. Infants failed to chunk speakers of unfamiliar languages when each doll within a pair produced a unique utterance (Experiment 2), but they succeeded when each doll within a pair produced the same utterance (Experiment 3). Infants' performance was not driven by low-level acoustical cues in the utterances given that infants failed to chunk when the dolls' speech was played backward (Experiment 4). Together, these results suggest that infants can leverage their early sensitivities to linguistic distinctions to hierarchically reorganize their memory representations, thereby overcoming working memory limits.

Individual differences in nonlinguistic event categorization predict later motion verb comprehension.

This study probes how individual differences in early event perception predict later verb knowledge. At Time 1, when infants were 13 to 15months of age, they saw videotaped silent scenes performed by a human actor. The goal was to see whether infants could form categories of path (a figure's trajectory with respect to a ground object) and manner (how an action is performed). Infants either saw the same manner (e.g., jogging) taking place across three different paths (around, through, and behind) or saw the same path (e.g., around a tent) taking place across three different manners (running, crawling, and walking). After familiarization, either the path or the manner was changed and visual fixation was monitored using preferential looking. At Time 2, the same children were tested on their comprehension of verbs in a two-choice pointing task showing two simultaneous actions (e.g., running vs. jumping). Success at categorization of path and manner at Time 1 predicted verb comprehension at Time 2, even when taking language knowledge at both time points into account. These preliminary results represent headway in identifying the factors that may contribute to children's language learning. They suggest that skill in categorizing semantic components present in nonlinguistic events is predictive of children's later verb vocabulary.

Social knowledge facilitates chunking in infancy.

Two experiments investigated whether infants can use their rich social knowledge to bind representations of individual objects into larger social units, thereby overcoming the three-item limit of working memory. In Experiment 1, 16-month-olds (n = 32) remembered up to four hidden dolls when the dolls had faced and interacted with each other in pairs, but not when they faced and interacted with the infant, suggesting that infants chunked the dolls into social pairs. In Experiment 2 (n = 16), infants failed to remember four dolls when they faced each other without interacting, indicating that interaction between the dolls was necessary to drive chunking. This work bridges a gap between social cognition and memory by demonstrating that infants can use social cues to expand memory.

Infants segment continuous events using transitional probabilities.

Throughout their 1st year, infants adeptly detect statistical structure in their environment. However, little is known about whether statistical learning is a primary mechanism for event segmentation. This study directly tests whether statistical learning alone is sufficient to segment continuous events. Twenty-eight 7- to 9-month-old infants viewed a sequence of continuous actions performed by a novel agent in which there were no transitional movements that could have constrained the possible upcoming actions. At test, infants distinguished statistically intact units from less predictable ones. The ability to segment events using statistical structure may help infants discover other cues to event boundaries, such as intentions, and carve up the world of continuous motion in meaningful ways.

Objects in a social world: Infants' object representational capacity limits are shaped by objects' social relevance.

Several decades of research have revealed consistent signature limits on infants' ability to represent objects. However, these signature representational limits were established with methods that often removed objects from their most common context. In infants' everyday lives, objects are very often social artifacts: they are the targets of agents' goal-directed actions, communications, and beliefs, and may have social content or relevance themselves. In this chapter, we explore the relationship between infants' object representational capacity limits and their processing of the social world. We review evidence that the social content and context of objects can shift infants' object representational limits. We discuss how taking the social world into account can yield more robust and ecologically valid estimates of infants' early representational capacities.

Violations of Core Knowledge Shape Early Learning.

Research on cognitive development has revealed that even the youngest minds detect and respond to events that adults find surprising. These surprise responses suggest that infants have a basic set of "core" expectations about the world that are shared with adults and other species. However, little work has asked what purpose these surprise responses serve. Here we discuss recent evidence that violations of core knowledge offer special opportunities for learning. Infants and young children make predictions about the world on the basis of their core knowledge of objects, quantities, and social entities. We argue that when these predictions fail to match the observed data, infants and children experience an enhanced drive to seek and retain new information. This impact of surprise on learning is not equipotent. Instead, it is directed to entities that are relevant to the surprise itself; this drive propels children-even infants-to form and test new hypotheses about surprising aspects of the world. We briefly consider similarities and differences between these recent findings with infants and children, on the one hand, and findings on prediction errors in humans and non-human animals, on the other. These comparisons raise open questions that require continued inquiry, but suggest that considering phenomena across species, ages, kinds of surprise, and types of learning will ultimately help to clarify how surprise shapes thought.

Expectancy violations promote learning in young children.

Children, including infants, have expectations about the world around them, and produce reliable responses when these expectations are violated. However, little is known about how such expectancy violations affect subsequent cognition. Here we tested the hypothesis that violations of expectation enhance children's learning. In four experiments we compared 3- to 6-year-old children's ability to learn novel words in situations that defied versus accorded with their core knowledge of object behavior. In Experiments 1 and 2 we taught children novel words following one of two types of events. One event violated expectations about the spatiotemporal or featural properties of objects (e.g., an object appeared to magically change locations). The other event was almost identical, but did not violate expectations (e.g., an object was visibly moved from one location to another). In both experiments we found that children robustly learned when taught after the surprising event, but not following the expected event. In Experiment 3 we ruled out two alternative explanations for our results. Finally, in Experiment 4, we asked whether surprise affects children's learning in a targeted or a diffuse way. We found that surprise only enhanced children's learning about the entity that had behaved surprisingly, and not about unrelated objects. Together, these experiments show that core knowledge - and violations of expectations generated by core knowledge - shapes new learning.

Cognitive development. Observing the unexpected enhances infants' learning and exploration.

Given the overwhelming quantity of information available from the environment, how do young learners know what to learn about and what to ignore? We found that 11-month-old infants (N = 110) used violations of prior expectations as special opportunities for learning. The infants were shown events that violated expectations about object behavior or events that were nearly identical but did not violate expectations. The sight of an object that violated expectations enhanced learning and promoted information-seeking behaviors; specifically, infants learned more effectively about objects that committed violations, explored those objects more, and engaged in hypothesis-testing behaviors that reflected the particular kind of violation seen. Thus, early in life, expectancy violations offer a wedge into the problem of what to learn.