Six‐Month‐Old Infants Predict Agents’ Goal‐Directed Actions on Occluded Objects

Infants can infer agents’ goals after observing agents’ goal‐directed actions on objects and can subsequently make predictions about how agents will act on objects in the future. We investigated the representations supporting these predictions. We familiarized 6‐month‐old infants to an agent who preferentially reached for one of two featurally distinct objects following a cue. At test, the objects were sequentially occluded from the infant in the agent's presence. We asked whether infants could generate action predictions without visual access to the relevant objects by measuring whether infants shifted their gaze to the location of the agent's hidden goal object following the cue. We also examined what infants represented about the hidden objects by removing one of the occluders to reveal either the original hidden object or the unexpected other object and measuring infants’ looking time. We found that, even without visual access to the objects, infants made predictive gazes to the location of the agent's occluded goal object, but failed to represent the features of either hidden object. These results suggest that infants make goal‐based action predictions when the relevant objects in the scene are occluded, but doing so may come at the expense of maintaining representations of the objects.     

It Is Not Just About Location: Infants Perseverate to Container Shape During Object Search

In searching for a toy hidden at a new location, infants will err by searching at the previously correct location. This study investigated the possibility that 8.5‐month‐old infants would perseverate on the basis of other visual features by which covers could be individuated. Infants saw a toy hidden under 1 of 2 distinctly shaped covers. Following successful retrievals from the Shape A cover, infants saw the toy hidden under the Shape B cover. On this B trial, the covers were at locations that had not been baited on the preceding trials, precluding location perseveration. The infants erred by choosing the unbaited Shape A cover more often than control infants presented with 1 type of cover throughout. The findings suggest that infants perseverate to cover shape and are form biases biased toward cover shape even when location information is sufficient to support retrieval.     

The Development of Gaze Following in a Third‐Party Context

Infants follow the gaze of an individual with whom they are directly interacting by the end of the first year. By 18 months infants are capable of learning novel words in observational (or third‐party) contexts (Floor & Akhtar, 2006). To examine third‐party gaze following in 12‐ and 18‐month‐olds, the parent and experimenter engaged in a conversation while the infant was present. For 8 trials approximately every 30 sec the experimenter would turn her head to the right or left to fixate on a toy placed on either side of the room with the parent following suit. In the first experiment, the parent was seated next to the infant and the experimenter opposite, whereas in the second experiment the positions of the adults were switched. In Experiment 1, 18‐month‐olds but not 12‐month‐olds followed gaze. In Experiment 2, 12‐month‐olds acquired a tendency to follow gaze during the experimental session. These results suggest that an incipient ability to follow third‐party gaze is present by 12 months and that infants acquire a more reliable and general ability to follow the gaze of noninteractive others between 12 and 18 months.     

The Effect of Simulated Self Versus Object Movement in a Nonsearch Task

This study examined 6‐month‐old infants' abilities to use the visual information provided by simulated self‐movement through the world, and movement of an object through the world, for spatial orientation. Infants were habituated to a visual display in which they saw a toy hidden, followed by either rotation of the point of observation through the world (simulated self‐movement) or movement of the object itself through the world (object movement). Following habituation, infants saw test displays in which the hidden toy reappeared at the correct or incorrect location, relative to the earlier movements. Infants habituated to simulated self‐movement looked longer at the recovery of the toy from an incorrect, relative to correct location. In contrast, infants habituated to object movement showed no differential looking to either correct or incorrect test displays. These findings are discussed within a theoretical framework of spatial orientation emphasizing the availability and use of spatial information.     

The Effect of the Number of A Trials on Performance on the A‐Not‐B Task

The A‐not‐B error (Piaget, 1954), which occurs when infants search perseveratively on reversal trials in a delayed‐response task, is one of the most widely studied phenomena in developmental psychology. Nonetheless, the effect of A‐trial experience on the probability and magnitude of this error remains unclear. In this study, 9‐month‐old infants were tested at location A until they searched correctly on 1, 6, or 11 A trials. Results revealed an effect of A trials on the proportion of infants who erred on the first B trial, and on the number of errors prior to a correct search at B (i.e., the error run). These effects were asymptotic, or U‐shaped, consistent with a dual‐process model according to which A‐trial experience increases habit strength but also provides opportunities for reflection on task structure.     

Infant Brain Responses to Object Weight: Exploring Goal‐Directed Actions and Self‐Experience

Recent work has suggested the value of electroencephalographic (EEG) measures in the study of infants' processing of human action. Studies in this area have investigated desynchronization of the sensorimotor mu rhythm during action execution and action observation in infancy. Untested but critical to theory is whether the mu rhythm shows a differential response to actions which share similar goals but have different motor requirements or sensory outcomes. By varying the invisible property of object weight, we controlled for the abstract goal (reach, grasp, and lift the object), while allowing other aspects of the action to vary. The mu response during 14‐month‐old infants' own executed actions showed a differential hemispheric response between acting on heavier and lighter objects. EEG responses also showed sensitivity to “expected object weight” when infants simply observed an experimenter reach for objects that the infants' prior experience indicated were heavier vs. lighter. Crucially, this neural reactivity was predictive—during the observation of the other reaching toward the object, before lifting occurred. This suggests that infants' own self‐experience with a particular object's weight influences their processing of others' actions on the object, with implications for developmental social‐cognitive neuroscience.     

Infant Looking Behavior in Ambiguous Situations: Social Referencing or Attachment Behavior?

Is infant looking behavior in ambiguous situations best described in terms of information seeking (social referencing) or as attachment behavior? Twelve‐month‐old infants were assigned to 1 of 2 conditions (Study 1); each infant's mother provided positive information about an ambiguous toy and an experimenter provided positive information. In Study 2, 12‐month‐old infants were assigned to 1 of 3 conditions: mother provided positive information about the toy, mother was inattentive, or mother provided negative information; the experimenter was inattentive. The infants preferred to look at the experimenter in almost all conditions and they regulated their behavior in accordance with information obtained from the experimenter. None of the studies lends support for an explanation in terms of behaviors deriving from the attachment system, and they raise questions concerning social referencing interpretations of infants' looking behavior. Other alternatives for explaining infant looking behavior in social referencing situations (e.g., associative learning) are discussed.     

10‐Month‐Olds Visually Anticipate an Outcome Contingent on Their Own Action

It is known that young infants can learn to perform an action that elicits a reinforcer, and that they can visually anticipate a predictable stimulus by looking at its location before it begins. Here, in an investigation of the display of these abilities in tandem, I report that 10‐month‐olds anticipate a reward stimulus that they generate through their own action: .5 sec before pushing a button to start a video reward, they increase their rate of gaze shifts to the reward location; and during periods of extinction, reward location gaze shifts correlate with bouts of button pushing. The results are consistent with the hypothesis that the infants have an expectation of the outcome of their actions: several alternative hypotheses are ruled out by yoked controls. Such an expectation may, however, be procedural, have minimal content, and is not necessarily sufficient to motivate action.     

Why do Infants Look at and Use Positive Information from Some Informants Rather Than Others in Ambiguous Situations?

Three laboratory experiments on social referencing examined whether infants’ tendencies to look at and use positive information from the experimenter could be interpreted from a perspective of novelty or expertise. In Study 1, novelty was manipulated. Forty‐eight 12‐month‐old infants participated. In a between‐subject design, a more novel or a less novel experimenter presented an ambiguous object and provided positive information. The infants looked more at and regulated their behavior more in accordance with information coming from the less novel experimenter. In Study 2, expertise was manipulated. Forty‐eight 12‐month‐old infants were exposed to one experimenter who showed expertise about the laboratory situation and one experimenter who did not show such competence. The infants looked more at and regulated their behavior more in accordance with information coming from the expert. In Study 3, 40 12‐month‐old infants participated. The infants were exposed to a toy‐expert who was either novel or familiar. The infants, in both groups, looked as much at the toy‐experts and used the information regardless of whether the novel or familiar toy‐expert had provided information. The findings suggest that novelty does not increase looking in ambiguous situations. Instead, the results support the expertise perspective of infant looking preferences.     

Cotton‐Top Tamarins' (Saguinus oedipus) Expectations About Occluded Objects: A Dissociation Between Looking and Reaching Tasks

Recent work with human infants and toddlers suggests a dissociation between performance on looking and reaching tasks. Specifically, infants appear to generate accurate representations of occluded objects and their actions when tested in expectancy violation looking tasks but often fail to use this information when reaching for occluded objects. We explore a similar dissociation in cotton‐top tamarin monkeys (Saguinus oedipus). We presented adult tamarins with an event in which a piece of food rolled behind an occluder and into a solid barrier. In Experiment 1, subjects were required to retrieve the hidden food using the location of the solid barrier. Like human toddlers, adult tamarins failed to take into account solidity information when reaching for an invisibly displaced object. In Experiments 2 and 3, we presented subjects with expectancy violation looking versions of the same solidity problem using an identical apparatus and setup. We presented subjects with an event in which a piece of food appeared to roll unexpectedly through a solid barrier or stopped at the appropriate spot. Although tamarins failed to locate the food in Experiment 1, the same subjects successfully detected violations of solidity in these 2 looking studies. This performance dissociation is discussed in light of similar dissociations in human toddlers and other primate species.     

The Goal Trumps the Means: Highlighting Goals is More Beneficial than Highlighting Means in Means‐End Training

Means‐end actions are an early‐emerging form of problem solving. These actions require initiating initial behaviors with a goal in mind. In this study, we explored the origins of 8‐month‐old infants’ means‐end action production using a cloth‐pulling training paradigm. We examined whether highlighting the goal (toy) or the means (cloth) was more valuable for learning to perform a well‐organized means‐end action. Infants were given the opportunity to both practice cloth‐pulling and view modeling of the action performed by an adult throughout the session. Infants saw either the same toy or the same cloth in successive trials, so that the goal or means were highlighted prior to modeling of the action. All infants improved throughout the session regardless of which aspect of the event was highlighted. Beyond this general improvement, repetition of goals supported more rapid learning and more sustained learning than did repetition of means. These findings provide novel evidence that, at the origins of means‐end action production, emphasizing the goal that structures an action facilitates the learning of new means‐end actions.     

The Influence of Labels,Non‐Labeling Sounds,and Source of Auditory Input on 9‐ and 15‐Month‐Olds' Object Categorization

This experiment examines the joint influence of auditory and social cues on infants' basic‐level and global categorization. Nine‐ and fifteen‐month‐olds were familiarized to a series of category exemplars in an object‐examining task. Objects were introduced with a labeling phrase, a non‐labeling sound, or no sound, and auditory input was presented orally by the experimenter or played on a hidden voice recorder. Novel objects from the familiarized category and a contrasting category were then presented. Results of analyses performed on novelty preference scores indicated that infants demonstrated basic‐level categorization in all conditions. However, infants at both age levels only demonstrated global categorization when labeling phrases were introduced. In addition, labels led to global categorization in 9‐month‐olds regardless of the source of those labels; however, labels only led to global categorization in 15‐month‐olds when the labels were presented orally by the experimenter.     

18‐Month‐Olds Predict Specific Action Mistakes Through Attribution of False Belief,Not Ignorance,and Intervene Accordingly

This study employed a new “anticipatory intervening” paradigm to tease apart false belief and ignorance‐based interpretations of 18‐month‐olds’ helpful informing. We investigated in three experiments whether 18‐month‐old infants inform an adult selectively about one of the two locations depending on the adult’s belief about which of the two locations held her toy. In experiments 1 and 2, the adult falsely believed that one of the locations held her toy. In experiment 3, the adult was ignorant about which of the two locations held her toy. In all cases, however, the toy had been removed from the locations and the locations contained instead materials which the adult wanted to avoid. In experiments 1 and 2, infants spontaneously and selectively informed the adult about the aversive material in the location the adult falsely believed to hold her toy. In contrast, in experiment 3, infants informed the ignorant adult about both locations equally. Results reveal that infants expected the adult to commit a specific action mistake when she held a false belief, but not when she was ignorant. Further, infants were motivated to intervene proactively. Findings reveal a predictive action‐based usage of “theory‐of‐mind” skills at 18 months of age.     

Detecting Transparent Barriers: Clear Evidence Against the Means‐End Deficit Account of Search Failures

The standard explanation of infants' search failures with hidden objects, despite an apparent sensitivity to them, is a deficit in the means‐end skill for retrieving objects from occluders. Studies equating means‐end demands for retrieving toys from transparent and opaque barriers challenge this account by showing that infants succeed more with visible objects. However, they suffer from a critical limitation: Infants may retrieve visible objects without noticing the transparent barriers in front of them. We addressed this concern by requiring infants to notice a barrier to retrieve a toy and specifically to pull down a rotating screen to retrieve a toy from behind it. Seven‐month‐olds used this means‐end skill more often with a transparent barrier than an opaque one. Thus, neither a means‐end deficit nor an ability to ignore transparent barriers fully accounts for search failures. Relations to other findings challenging the means‐end deficit account and implications for approaches to studying cognitive development are discussed.     

Sensitivity to Confidence Cues Increases during the Second Year of Life

We investigated the emergence in infancy of a preference to imitate individuals who display confidence over lack of confidence. Eighteen‐ and 24‐month‐olds (N = 70) were presented with an experimenter who demonstrated the use of several objects accompanied by either nonverbal expressions of confidence or lack of confidence. At 24 months, infants were more likely to imitate the actions when demonstrated by a confident experimenter than by an unconfident experimenter; 18‐month‐olds showed no such preference. The experimenter then presented an additional imitation trial and a word‐learning trial while displaying a neutral expression. Twenty‐four‐month‐olds persisted in preferentially imitating a previously confident experimenter, but prior confidence had no effect on their word learning. These findings demonstrate a developmental increase in infants’ use of confidence cues toward the end of the second year of life.     

Decalage in Infants' Search for Mothers Versus Toys Demonstrated With a Delayed Response Task

Thirty‐one infants, 7 to 14 months of age, were tested on object and mother permanence using a delayed response task (Diamond, 1985), in which a delay period is enforced before infants are allowed to search for hidden objects. Infants were tested in 2 separate conditions in which they searched for their mothers and a large toy, both of which were hidden under curtained tables. The delay period before search was allowed was incremented after each successful trial until infants either failed to search or searched in the wrong location. Infants were scored for the maximum delay preceding a successful search. The results from 17 infants showed that infants were able to withstand significantly longer delays before successful search for the mother than for the toy. These results support previous studies showing that mother permanence precedes object permanence in infants older than 8 months.     

Emergence of Selective Social Referencing in Infancy

Seven and 10‐month‐old infants were presented with a remote‐controlled toy dog that intermittently barked at 30‐sec intervals as they faced an experimenter who either attended to them (look toward condition) or looked away (look away condition). Seven‐month‐old infants' looking toward the experimenter was significantly greater after the dog barking events compared to before regardless of experimental condition. In contrast, 10‐month‐old infants' looks were significantly greater after the barking events compared to before only when the experimenter was attending to them. These results suggest that by 10 months infants monitor and refer to people in an ambiguous situation depending on their attention toward them. This development is viewed as indexing the emergence of an intentional stance in social referencing by 10 months of age.     

How Manual Object Exploration is Associated with 7‐ to 8‐Month‐Old Infants’ Visual Prediction Abilities in Spatial Object Processing

The present experiment examined whether infants’ visual prediction performance of the appearance of objects moving in space is related to their manual object exploration ability. Fifty‐five 7‐ to 8‐month‐old infants were tested. A visual object prediction paradigm was developed during which a three‐dimensional object was presented in a live eye‐tracking setting. During familiarization, the object rotated back and forth along the vertical axis. While the object was moving, two target parts of it were briefly occluded from view and uncovered again as the object changed its direction of motion. In the test phase, the entire object was rotated around 90° and now rotated along the horizontal axis. We recorded infants’ eye movements directed at the target locations and analyzed the prediction rates. All of the infants also participated in a manual object exploration task, in which they freely explored five toy blocks. Infants with a higher level of object exploration skill had higher prediction rates during test trials as compared to infants with less proficient object exploratory actions. The results support the interpretation that advanced manual object exploration experience is associated with infants’ advanced visual prediction ability of the appearance of objects moving in space.     

12‐Month‐Olds Produce Others' Intended but Unfulfilled Acts

Following Meltzoff's (1995) behavioral reenactment paradigm, this study investigated the ability of 12‐month‐olds (N = 44) to reproduce a model's attempted‐but‐failed actions on objects. Testing was conducted using a novel set of objects designed to enable young infants to readily identify the potential outcome of the model's actions. Infants who saw an adult's attempted‐but‐failed actions now produced her intended outcomes at an equivalent rate to infants who saw the model's completed acts, and significantly more so than infants who either observed an adult manipulating the test apparatus using nontarget actions or who did not see any actions demonstrated on the test apparatus. This result shows that, contrary to previous studies, 12‐month‐olds can produce the intended but unconsummated acts of others.