Décalage in infants' knowledge about occlusion and containment events: Converging evidence from action tasks

In the present research, 6-month-old infants consistently searched for a tall toy behind a tall as opposed to a short occluder. However, when the same toy was hidden inside a tall or a short container, only older, 7.5-month-old infants searched for the tall toy inside the tall container. These and control results (1) confirm previous violation-of-expectation (VOE) findings of a décalage in infants' reasoning about height information in occlusion and containment events; (2) cast doubt on the suggestion that VOE tasks overestimate infants' cognitive abilities; and (3) support recent proposals that infants use their physical knowledge to guide their actions when task demands do not overwhelm their limited processing resources.     

Décalage in infants' knowledge about occlusion and containment events: converging evidence from action tasks

In the present research, 6-month-old infants consistently searched for a tall toy behind a tall as opposed to a short occluder. However, when the same toy was hidden inside a tall or a short container, only older, 7.5-month-old infants searched for the tall toy inside the tall container. These and control results (1) confirm previous violation-of-expectation (VOE) findings of a décalage in infants' reasoning about height information in occlusion and containment events; (2) cast doubt on the suggestion that VOE tasks overestimate infants' cognitive abilities; and (3) support recent proposals that infants use their physical knowledge to guide their actions when task demands do not overwhelm their limited processing resources.     

The development of young infants' intuitions about support

Previous research has shown that 3-month-old infants, like adults, expect a box to be stable when it is in full contact with a platform, and to fall when it loses all contact with the platform. Do young infants also have expectations about what should happen when the box is only in partial contact with the platform? The present research was designed to address this question. In Experiment 1, 6.5-month-old infants saw two test events: a full-contact and a partial-contact test event. In both events, the infants watched the extended finger of a gloved hand push a box along the top of a platform. In the full-contact event, the box was pushed until its leading edge reached the end of the platform. In the partial-contact event, the box was pushed until only 15% or 70% of its bottom surface remained on the platform. The infants looked reliably longer at the partial-than at the full-contact event when 15%, but not 70%, of the box rested on the platform. These results suggested that the infants were able to judge how much contact was needed between the box and the platform for the box to be stable. A control condition provided evidence for this interpretation. In Experiment 2, 5.5- to 6-month-old infants were found to look equally at the full- and the partial-contact events, even when only 15% of the box's bottom surface remained on the platform. This result suggested that prior to 6.5 months of age infants perceive any amount of contact between the box and the platform to be sufficient to ensure the box's stability. Interpretations of this developmental sequence are considered in the Conclusion.     

A computational and neuropsychological account of object-oriented behaviours in infancy

Infants under 7 months of age fail to reach behind an occluding screen to retrieve a desired toy even though they possess sufficient motor skills to do so. However, even by 3.5 months of age they show surprise if the solidity of the hidden toy is violated, suggesting that they know that the hidden toy still exists. We describe a connectionist model that learns to predict the position of objects and to initiate a response towards these objects. The model embodies the dual-route principle of object information processing characteristic of the cortex. One route develops a spatially invariant surface feature representation of the object whereas the other route develops a feature blind spatial–temporal representation of the object. The model provides an account of the developmental lag between infants’ knowledge of hidden objects and their ability to demonstrate that knowledge in an active retrieval task, in terms of the need to integrate information across multiple object representations using (associative) connectionist learning algorithms. Finally, the model predicts the presence of an early dissociation between infants’ ability to use surface features (e.g. colour) and spatial–temporal features (e.g. position) when reasoning about hidden objects. Evidence supporting this prediction has now been reported.     

Effects of balance relations between objects on infant’s object segregation

Young infants are sensitive to support relations between objects. However, the types of contact perceived to be sufficient for object support change over development. At 4.5 months of age, infants expect an object to be adequately supported when in contact with another object. By 6.5 months, this simple contact/no‐contact distinction is refined to account for proportion of contact: an object is perceived to be supported when 70% of its bottom surface is in contact with another object, but it is not perceived to be supported when 15% is contacted. Here, we employ an object segregation paradigm to investigate whether 8‐month‐old infants’ judgments of support relations are mediated by assessments both of the proportion of contact and of the position of contact. Infants in the current experiments viewed test displays consisting of two objects, a long thin object (a box) and a smaller roughly cubic object (a box in Experiment 1, a cylinder in Experiments 2 and 3). Two basic positions of contact were used, such that either the centers or the lateral edges of the two objects were aligned. The proportion of contact was manipulated across experiments by having the smaller object support the larger or the larger object support the smaller. There was a significant effect of position of contact when only a small proportion of the upper object was contacted by the lower object. However, position of contact was found not to matter when all of the upper object was in contact with the lower object. We conclude that 8‐month‐old infants’ judgments of support relations are influenced by both proportion and position of supporting contact. We integrate the findings from the current experiments into the general developmental framework proposed by Baillargeon and colleagues.     

Young infants' reasoning about hidden objects: evidence from violation-of-expectation tasks with test trials only

The present research examined alternative accounts of prior violation-of-expectation (VOE) reports that young infants can represent and reason about hidden objects. According to these accounts, young infants' apparent success in these VOE tasks reflects only novelty and familiarity preferences induced by the habituation or familiarization trials in the tasks. In two experiments, 4-month-old infants were tested in VOE tasks with test trials only. The infants still gave evidence that they could represent and reason about hidden objects: they were surprised, as indicated by greater attention, when a wide object became fully hidden behind a narrow occluder (Experiment 1) or inside a narrow container (Experiment 2). These and control results demonstrate that young infants can succeed at VOE tasks involving hidden objects even when given no habituation or familiarization trials. The present research thus provides additional support for the conclusion that young infants possess expectations about hidden objects. Methodological issues concerning the use of habituation or familiarization trials in VOE tasks are also discussed.     

Can 15-month-old infants understand pretence? An investigation using the 'violation-of-expectation' paradigm

Productive tests are unsuitable for measuring infants' earliest understanding of pretence, because performance demands may render infants unable to produce the actions required to pass the test. Recently, Onishi, Baillargeon and Leslie (2007) used the violation-of-expectation (VOE) paradigm as a measure of infants' understanding of others' pretence that is free from such performance demands. They found that 15-month-old infants looked longer at an Unexpected event in which an actor pretended to pour into one cup but pretended to drink from another cup, compared to pretending to pour and drink with the same cup. On this basis, they argued that 15-month-old infants expect others' pretence to be consistent, demonstrating their understanding of others' pretence. However, infants may have responded to expectations they had about familiar action sequences, rather than to pretence per se. To test this hypothesis, the current study firstly replicated Onishi et al.'s results in a sample of 28 typically developing 15-month-old infants, and then added a condition using closely matched real versions of their pretend VOE tasks. It was found that infants looked longer at unexpected events, whether or not the events were real or pretend. It was concluded that 15-month-old infants may look longer at pretend events due to violations of expectations they have about familiar action sequences, rather than because they understand others' pretence behaviour.     

Why do young infants fail to search for hidden objects?

Recent evidence indicates that infants as young as 3.5 months of age understand that objects continue to exist when hidden (Baillargeon, 1987a; Baillargeon & DeVos, 1990). Why, then, do infants fail to search for hidden objects until 7 to 8 months of age? The present experiments tested whether 5.5-month-old infants could distinguish between correct and incorrect search actions performed by an experimenter. In Experiment 1, a toy was placed in front of (possible event) or under (impossible event) a clear cover. Next, a screen was slid in front of the objects, hiding them from view. A hand then reached behind the screen and reappeared holding the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they understood that the hand's direct reaching action was sufficient to retrieve the toy when it stood in front of but not under the clear cover. The same results were obtained in a second condition in which a toy was placed in front of (possible event) or behind (impossible event) a barrier. In Experiment 2, a toy was placed under the right (possible event) or the left (impossible event) of two covers. After a screen hid the objects, a hand reached behind the screen's right edge and reappeared first with the right cover and then with the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they realized that the hand's sequence of action was sufficient to retrieve the toy when it stood under the right but not the left cover. A control condition supported this interpretation. Together, the results of Experiments 1 and 2 indicate that by 5.5 months of age, infants not only represent hidden objects, but are able to identify the actions necessary to retrieve these objects. The implications of these findings for a problem solving explanation of young infants' failure to retrieve hidden objects are considered.     

Perceptual Sensitivity and Motoric Competence in 5- and 6-Month-Old Infants

The authors explored whether 5- to 6-month-old infants were sensitive to perceptual information and how they used perception as a recognition cue to search for a hidden object. In addition, the authors categorized and examined infant grasp by developmental effectiveness to determine any impact on infant search behaviors. In a within-participants design, 20 infants were presented with a toy in 2 occluder conditions. The toy was hidden under either a thick, camouflaging cloth or a thin, semitransparent cloth. The data revealed significant effects of perceptual sensitivity, age, and motor sophistication on search tasks. The results suggest that motor competence might be a limiting factor in infants' abilities to link motoric responses to notions about an object.     

Perceptual sensitivity and motoric competence in 5- and 6-month-old infants

The authors explored whether 5- to 6-month-old infants were sensitive to perceptual information and how they used perception as a recognition cue to search for a hidden object. In addition, the authors categorized and examined infant grasp by developmental effectiveness to determine any impact on infant search behaviors. In a within-participants design, 20 infants were presented with a toy in 2 occluder conditions. The toy was hidden under either a thick, camouflaging cloth or a thin, semitransparent cloth. The data revealed significant effects of perceptual sensitivity, age, and motor sophistication on search tasks. The results suggest that motor competence might be a limiting factor in infants' abilities to link motoric responses to notions about an object.     

Knowing who dunnit: Infants identify the causal agent in an unseen causal interaction

Preverbal infants can represent the causal structure of events, including distinguishing the agentive and receptive roles and categorizing entities according to stable causal dispositions. This study investigated how infants combine these 2 kinds of causal inference. In Experiments 1 and 2, 9.5-month-olds used the position of a human hand or a novel puppet (causal agents), but not a toy train (an inert object), to predict the subsequent motion of a beanbag. Conversely, in Experiment 3, 10- and 7-month-olds used the motion of the beanbag to infer the position of a hand but not of a toy block. These data suggest that preverbal infants expect a causal agent as the source of motion of an inert object.     

Object retrieval in the 1st year of life: learning effects of task exposure and box transparency

Before 12 months of age, infants have difficulties coordinating and sequencing their movements to retrieve an object concealed in a box. This study examined (a) whether young infants can discover effective retrieval solutions and consolidate movement coordination earlier if exposed regularly to such a task and (b) whether different environments, indexed by box transparency, would impact the rate of learning and time of discovery of these solutions. Infants (N=12) were presented with an object retrieval task every week from 6 1/2 months of age until they were able to retrieve the toy from the box using coordinated two-handed patterns for 3 weeks. To reach that criterion, infants tested with an opaque box took 2 1/2 months and infants tested with a semitransparent box took 1 1/2 months. Both groups outperformed age-matched controls who received a one-time exposure to the task. Repeated exposure to the task and vision of the toy significantly enhanced this process of solution discovery.     

Infants' ability to use object kind information for object individuation.

The present studies investigate infants reliance on object kind information in solving the problem of object individuation. Two experiments explored whether adults, 10- and 12-month-old infants could use their knowledge of ducks and cars to individuate an ambiguous array consisting of a toy duck perched on a toy car into two objects. A third experiment investigated whether 10-month-old infants could use their knowledge of cups and shoes to individuate an array consisting of a cup perched on a shoe into two objects. Ten-month-old infants failed to use object kind information alone to resolve the ambiguity with both pairs of objects. In contrast, infants this age succeeded in using spatiotemporal information to segment the array into two objects, i.e. they succeeded if shown that the duck moved independently relative to the car, or the cup relative to the shoe. Twelve-month-old infants, as well as adults, succeeded at object individuation on the basis of object kind information alone. These findings shed light on the developmental course of object individuation and provide converging evidence for the Object-first Hypothesis [Xu, F., Carey, S., 1996; Xu, F., 1997b]. Early on, infants may represent only one concept that provides criteria for individuation, namely physical object; kind concepts such as duck, car, cup, and shoe may be acquired later in the first year of life.     

Direct touches to clear barriers: developmental sensitivity of a new measure of the production of ineffective responses in infancy

Current interpretation of the object retrieval task ( Diamond, 1990 ) as an infant assessment of response inhibition requires evidence that younger infants make more ineffective attempts to retrieve toys through clear barriers. On two 30-second trials, infants (9 or 11 months of age) saw an inaccessible toy in the front or back of a clear box. The location of the infants touches corresponded with the toy's location and, on the second trial, the younger infants touched the box more. In previous research nonhuman primates with orbital-frontal, but not dorsa-lateral, lesions also made ineffective barrier touches. The current developmental decreases in barrier touches may selectively tap developmental increases in inhibitory control supported by the developing orbital-frontal cortex.     

Infants' coordination of auditory and visual depth information.

Using the preferential-looking procedure infants 5, 7, and 9 months of age were presented two videoimages side by side on separate monitors accompanied by a soundtrack that matched one of the images. Each infant was presented: (1) a stationary drum-beating toy paired with the same toy approaching and receding in depth, to assess infants' recognition both that changing sound amplitude is a property of an object that is moving in space and that constancy in amplitude is a property of a stationary object; (2) a drum-beating toy moving horizontally paired with one approaching and receding in depth, to assess infants' recognition that systematic increases and decreases in amplitude accompany object movement in a particular dimension, namely depth; and (3) two identical toys alternately approaching and receding in depth but out of phase (i.e., one approaching while the other is receding), to assess infants' recognition that increases and decreases in amplitude accompany a particular type of object movement in depth. Measures of mean duration of looking time indicated that the 5-month-olds looked reliably to the correct videoimage only for the stationary toy paired with the constant amplitude sound. The 7-month-olds recognized that changes in amplitude accompany object movement in depth but did not coordinate auditory with visual depth information as well as older infants. The 9-month-olds looked reliably to the correct videoimages in all conditions. Possible contributing factors to these developmental trends in performance are discussed.     

The effects of cue distinctiveness on infants' manual search

Nine- and sixteen-month-old infants were repeatedly presented a manual search problem in which a toy was hidden in one of two containers, which were then moved into reach. The distinctiveness of the containers or their closeness during the movement was varied in different conditions. Overall, the older infants performed better than younger infants, performance improved across trials, and there were more correct searches when the containers or trajectories were distinctive. Analyses of visual orienting indicated that infants learned to restrict their looking to the hiding place. The ability to maintain attention to discriminative cues may be instrumental to progress in delayed-reaction and object permanence tasks.     

Visual development in human infants: Binding features,surfaces, and objects

The development of visual binding in humans has been investigated with psychophysical tasks assessing the extent to which young infants achieve perceptual completion of partly occluded objects. These experiments lead to two conclusions. First, neonates are capable of figure-ground segregation, but do not perceive the unity of a centre-occluded object; the ability to perceive object unity emerges over the first several postnatal months. Second, by 4 months, infants rely on a range of Gestalt visual information in perceiving unity, including common motion, alignment, and good form. This developmental pattern is thought to be built on the ability to detect, and then utilize, appropriate visual information in support of the binding of features into surfaces and objects. Evidence from changes in infant attention, computational modelling, and developmental neurophysiology is cited that is consistent with this view.     

Sensitivity to communicative relevance tells young children what to imitate

How do children decide which elements of an action demonstration are important to reproduce in the context of an imitation game? We tested whether selective imitation of a demonstrator’s actions may be based on the same search for relevance that drives adult interpretation of ostensive communication. Three groups of 18‐month‐old infants were shown a toy animal either hopping or sliding (action style) into a toy house (action outcome), but the communicative relevance of the action style differed depending on the group. For the no prior information group, all the information in the demonstration was new and so equally relevant. However, for infants in the ostensive prior information group, the potential action outcome was already communicated to the infant prior to the main demonstration, rendering the action style more relevant. Infants in the ostensive prior information group imitated the action style significantly more than infants in the no prior information group, suggesting that the relevance manipulation modulated their interpretation of the action demonstration. A further condition (non‐ostensive prior information) confirmed that this sensitivity to new information is only present when the ‘old’ information had been communicated, and not when infants discovered this information for themselves. These results indicate that, like adults, human infants expect communication to contain relevant content, and imitate action elements that, relative to their current knowledge state or to the common ground with the demonstrator, is identified as most relevant.     

Verbal and Nonverbal Interactions of Four- and Five-Year-Old Friends in Potential Conflict Situations

Dyads of 4- and 5-year-old friends and nonfriends attending preschools in central Italy were identified by friendship nominations. The 217 dyads of friends and non-friends participated in 2 closed-field tasks designed to simulate real-life situations of potential conflict. In the 4-year-old cohort, there were no significant differences in the behavior of the partners in either of the situations. However, at age 5 years, friends respected the rules of a fast-paced competitive game significantly more than did nonfriends. In discussing how to share a single object (a chocolate egg with a toy inside), 5-year-old friends were more likely to reach agreement than were nonfriends. The results suggest important developmental changes in the processes of negotiation and sharing within the preschool years.     

Verbal and nonverbal interactions of four- and five-year-old friends in potential conflict situations

Dyads of 4- and 5-year-old friends and nonfriends attending preschools in central Italy were identified by friendship nominations. The 217 dyads of friends and non-friends participated in 2 closed-field tasks designed to simulate real-life situations of potential conflict. In the 4-year-old cohort, there were no significant differences in the behavior of the partners in either of the situations. However, at age 5 years, friends respected the rules of a fast-paced competitive game significantly more than did nonfriends. In discussing how to share a single object (a chocolate egg with a toy inside), 5-year-old friends were more likely to reach agreement than were nonfriends. The results suggest important developmental changes in the processes of negotiation and sharing within the preschool years.