Development of three-dimensional object completion in infancy

Three-dimensional (3D) object completion was investigated by habituating 4- and 6-month-old infants (n= 24 total) with a computer-generated wedge stimulus that pivoted 15 degrees , providing only a limited view. Two displays, rotating 360 degrees , were then shown: a complete, solid volume and an incomplete, hollow form composed only of the sides seen during habituation. There were no reliable preferences for either test display by 4-month-olds. At 6 months, infants showed a reliable novelty preference for the incomplete test display. Infants in a control group (n= 24) not habituated to the limited-view wedge preferred neither test display. By 6 months, infants may represent simple objects as complete in 3D space despite a limited perspective. Possible mechanisms of development of 3D object completion are discussed.     

Anticipatory Reaching by Infants and Adults: The Effect of Object Features and Apertures in Opaque and Transparent Screens

Perception of the manner in which objects may be grasped was examined in a series of experiments with adults and 10-month-old infants; visuomotor adjustment in hand orientation before making contact with objects served as the index throughout. In the first experiment, infants modified their hand orientation to match more closely the long axis of an object. They did so even though the target object could have been grasped by either end with hands oriented orthogonally to the long axis of the object. In two subsequent experiments involving reaching through narrow apertures to grasp the target, anticipatory adjustments in hand posture were evident for adults but not for infants. However, anticipatory adjustments by infants, sometimes appropriate and sometimes inappropriate, were made when the object was of such a size that it could neither be grasped nor retrieved through the aperture. In the final experiment, infants directed their hands first toward a handle, the only graspable part of an object, and oriented their hands so as to be nearly parallel with it prior to contact. This was the only orientation in which a grasp was possible. It was concluded that infants at 10 months respond more appropriately to object properties than to surface apertures that place limitations on how an object may be grasped.     

Shape recognition in infancy: visual integration of sequential information

To investigate the integration of visual information across space and time, infants watched the contour of a shape being traced out by a moving point source of light and then viewed 2 objects: 1 with the shape they had just seen traced and 1 with a novel shape. In the first study, which varied the number of tracings (velocity about 16.7 cm/sec), 12-month-olds looked longer at the novel object in all conditions, indicating that they recognized the similarity between the alternative object and tracing of like contour. Study 2, which varied velocity (14.7 and 7.4 cm/sec), stimuli, and the number of tracings, provided evidence for the generalizability of these results but indicated that performance suffered at the slower speed. Studies 3 and 4 held velocity constant (14.7 cm/sec) while varying the size of the tracings and age of the infant: 12-month-olds, but not 6-month-olds, recognized figures in instances where it took up to 10 sec to complete a single tracing. Because it took so long to complete many of the tracings, central rather than purely retinal mechanisms appear to be involved in integrating shape in these situations.     

You go this way and I'll go that way: developmental changes in infants' detection of correlations among static and dynamic features in motion events

Four experiments utilizing the habituation procedure examined 10- to 18-month-olds' ability to detect and encode correlations among features in a motion event (N = 136). Infants were habituated to two events in which objects-with distinct parts and a distinct body-moved across a screen along a rectilinear or curvilinear motion path. Infants were then tested with one familiar event and three events in which one feature of the object (parts, body, or motion path) was presented in a novel combination with the other features. The results of the experiments revealed that 10-month-olds process independently static features in an event, but do not process correlations among dynamic features; whereas 14-month-olds detect the correlation between an object's parts and its motion trajectory, but only when the movement of parts is correlated with the motion of the object. Further, the data show that 18-month-olds detect correlations between all three features when the parts of the object move, but they detect only the relation between parts and motion path when the parts do not move. It is proposed that infants develop representations for the static and dynamic properties of objects through a sensitive perceptual system that detects individual features, whole objects, and movement properties, and a domain-general associative learning mechanism that encodes independent features and correlations among features.     

Effective Action by Infants to Contact Objects by Reaching and Leaning

The ability of infants aged 8–12 months to coordinate their arm and trunk movements to contact an object located in different positions was investigated in 2 experiments. In the first, 8- and 10-month-old infants reached for near objects but both reached and leaned for more distant ones indicating that they perceived that forward leaning extends the range of contact beyond that of reaching alone. In addition, arm and trunk movements were initiated simultaneously; visual information concerning object distance was sufficient to activate an integrated reaching-and-leaning response. Object distances were increased and a mechanical aid was provided on half the trials in the second experiment with 10- and 12-month-old infants. For both age groups the degree of leaning was reduced for objects that were out of reach without the aid. Only older infants were able to use the aid to extend partially their range of contact. Overall the results support the conclusions that, by at least 8 months, infants perceive that leaning extends their effective reaching space; by 10 months they perceive the limits within which reaching together with leaning is likely to be effective; and by 12 months they begin to perceive how this space may be extended by a mechanical aid.     

Six-month-old infants' categorization of containment spatial relations

Six-month-old infants' ability to form an abstract category of containment was examined using a standard infant categorization task. Infants were habituated to 4 pairs of objects in a containment relation. Following habituation, infants were tested with a novel example of the familiar containment relation and an example of an unfamiliar relation. Results indicate that infants look reliably longer at the unfamiliar versus familiar relation, indicating that they can form a categorical representation of containment. A second experiment demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. Together, the results indicate that by 6 months, infants can recognize a containment relation from different angles and across different pairs of objects.     

Development of knowledge of visual-tactual affordances of substance

Infants of 12 months were familiarized in the dark with an object of either a hard or an elastic (spongy) substance. Following 60 sec of manipulation, a visual preference test was given with simultaneous presentation of 2 films of identical objects, 1 moving in a pattern characteristic of a rigid object and 1 moving in a pattern characteristic of an elastic object. Infants handled the 2 substances differently in an appropriate manner and looked preferentially with more and longer first looks to the type of substance familiarized. A replication of this experiment with familiarization in the light yielded comparable results. A third experiment with 1-month-old infants allowed them to mouth objects of either a hard or a soft substance for haptic familiarization and then tested looking preferences with real objects moving rigidly or deforming. These infants looked longer at the object moving in a manner characteristic of the novel substance. The results, together, suggest that quite young infants detect intermodal invariants specifying some substances and perceive the affordance of the substance.     

Infants' cross-modal transfer from solid objects to their graphic representations

12-month-old infants were familiarized either tactually or visually with objects and then tested for visual recognition memory using either (1) the familiar and a novel object, (2) colored pictures of the objects, or (3) outline drawings of them. In Study 1, infants showed recognition memory on all 3 visual intramodal problems but showed cross-modal transfer only when objects were used as test stimuli. With increased familiarization times in Study 2, transfer from tactually presented samples to both pictorial displays was achieved, indicating that after feeling an object the infants were able to recognize it visually solely on the basis of its contour. With reduced familiarization times in Study 3, there was no evidence for transfer from visually presented samples to the 2 pictorial displays, replicating the pattern of results observed cross-modally in Study 1 and suggesting that, at least in certain respects, cross-modal and intramodal perception follow similar principles.     

Picturing Objects in Infancy

Infants’ transfer of information from pictures to objects was tested by familiarizing 9‐month‐olds (N = 31) with either a color or black‐and‐white photograph of an object and observing their preferential reaching for the real target object versus a distractor. One condition tested object recognition by keeping both objects visible, and the other tested object representation by hiding both objects. On visible trials, infants reached more for the distractor, indicating they recognized the target object from its picture. On hidden trials, infants reached more for the target object, suggesting they formed a continued representation of the object based on its picture. Photograph color had no effect. Infants thus show picture‐to‐object transfer by 9 months with preferential reaching, even with black‐and‐white pictures.     

Young Children’s Representations of Spatial and Functional Relations Between Objects

Three experiments investigated changes from 15 to 30 months of age in children’s (N = 114) mastery of relations between an object and an aperture, supporting surface, or form. When choosing between objects to insert into an aperture, older children selected objects of an appropriate size and shape, but younger children showed little selectivity. Further experiments probed the sources of younger children’s difficulty by comparing children’s performance placing a target object in a hole, on a 2‐dimensional form, or atop another solid object. Together, the findings suggest that some factors limiting adults’ object representations, including the difficulty of comparing the shapes of positive and negative spaces and of representing shapes in 3 dimensions, contribute to young children’s errors in manipulating objects.     

Transition from crawling to walking and infants' actions with objects and people

Associations between infants' transition to walking and object activities were examined. Fifty infants were observed longitudinally during home observations. At 11 months, all infants were crawlers; at 13 months, half became walkers. Over age, infants increased their total time with objects and frequency of sharing objects with mothers. Bidirectional influences between locomotion and object actions were found. Walking was associated with new forms of object behaviors: Walkers accessed distant objects, carried objects, and approached mothers to share objects; crawlers preferred objects close at hand and shared objects while remaining stationary. Earlier object activities predicted walking status: Crawlers who accessed distant objects, carried objects, and shared objects over distances at 11 months were more likely to walk by 13 months.     

Generalization of learning in three-and-a-half-month-old infants on the basis of amodal relations

Infants of 3.5 months (N = 124) were given the opportunity to learn to relate two objects and their natural, distinctive sounds during a training phase. The objects and sounds were united by temporal synchrony and amodal audiovisual information specifying object composition. Infants then participated in one of three types of transfer tests (requiring low, moderate, or high degrees of generalization) to measure the extent to which intermodal knowledge generalized to a new task and across events (familiar events; change in color/shape; change in substance, motion, and color/shape). Results indicated that infants tested with the familiar events and with events of a new color/shape showed learning and transfer of knowledge. In contrast, infants tested with events of a new substance, motion, and color/shape showed no generalization of learning. Thus, infants of 3.5 months appear to show a moderate degree of generalization of intermodal knowledge across events. Although this knowledge is not restricted to the events of original learning, it cannot yet be flexibly extended across a variety of contexts.     

The Influence of Shape Similarity and Shared Labels on Infants'' Inductive Inferences about Nonobvious Object Properties

This study examined the influence of object labels and shape similarity on 16- to 21-month-old infants' inductive inferences. In three experiments, a total of 144 infants were presented with novel target objects with or without a nonobvious property, followed by test objects that varied in shape similarity to the target. When objects were not labeled, infants generalized the nonobvious property to test objects that were highly similar in shape (Experiment 1). When objects were labeled with novel nouns, infants relied both on shape similarity and shared labels to generalize properties (Experiment 2). Finally, when objects were labeled with familiar nouns, infants generalized the properties to those objects that shared the same label, regardless of shape similarity (Experiment 3). The results of these experiments delineate the role of perceptual similarity and conceptual information in guiding infants' inductive inferences.     

When less is more: how infants learn to form an abstract categorical representation of support

Two experiments explored how infants learn to form an abstract categorical representation of support (i.e., on) when habituated to few (i.e., 2) or many (i.e., 6) examples of the relation. When habituated to 2 pairs of objects in a support relation, 14-month-olds, but not 10-month-olds, formed the abstract spatial category (i.e., generalized the relation to novel objects). When habituated to 6 object pairs in a support relation, infants did not attend to the relation. The results indicate that infants learn to form an abstract spatial category of support between 10 and 14 months and that having fewer object pairs depicting this relation facilitates their acquisition of the abstract categorical representation.     

Four-month-old infants' sensitivity to binocular and kinetic information for three-dimensional-object shape

4-month-old infants were tested for sensitivity to kinetic and binocular information for 3-dimensional-object shape. The study included 2 tests: a test for sensitivity to binocular disparity and a shape perception test. The disparity sensitivity test used a preferential looking procedure developed by Held, Birch, and Gwiazda. On the basis of the results of this test, infants were assigned to disparity-sensitive and disparity-insensitive groups. In the shape perception test, a "transfer-across-depth-cues" method was employed. Infants were habituated to a rotating object whose shape was specified by kinetic information and were then presented with stationary stereograms specifying the same object and a novel-shaped object. The disparity-sensitive infants looked significantly longer at the novel object than at the familiar object, whereas the disparity-insensitive infants showed no difference in looking time to the novel and the familiar objects. The results indicate that disparity-sensitive 4-month-old infants can perceive 3-dimensional-object shape from kinetic and binocular depth information.     

!Kung Infancy: The Social Context of Object Exploration

The present study consists of new analyses of systematic observations of Kung infants made by Konner during the late 1960s and early 1970s. Our intent was to examine claims about the role of object sharing in development by describing how Kung infants develop interest in objects and how their caregivers act toward them when they are engaged in object-related acts. Results indicated that infants first displayed sustained interest in objects beginning at 4 months of age and that, beginning at about 8 months, they also began to engage in relational play and to give objects to others. Others tended to ignore infants during episodes of object manipulation and play, but moments of object offering were often socially embedded. These findings provide support for claims that there are universal changes in infants' involvement with objects and that their involvement is channeled in a culturally relevant manner by their caregivers.     

Common Themes and Cultural Variations in Japanese and American Mothers' Speech to Infants

This study explored both universal features and cultural variation in maternal speech. Japanese and American mothers' speech to infants at 6, 12, and 19 months was compared in a cross-sectional study of 60 dyads observed playing with toys at home. Mothers' speech in both cultures shared common characteristics, such as linguistic simplification and frequent repetition, and mothers made similar adjustments in their speech to infants of different ages. American mothers labeled objects more frequently and consistently than did Japanese mothers, while Japanese mothers used objects to engage infants in social routines more often than did American mothers. American infants had larger noun vocabularies than did Japanese infants, according to maternal report. The greater emphasis on object nouns in American mothers' speech is only partially attributable to structural differences between Japanese and English. Cultural differences in interactional style and beliefs about child rearing strongly influence the structure and content of speech to infants.     

The Development of Perceptual Completion Abilities: Infants' Perception of Stationary, Partially Occluded Objects

We explored infants' ability to perceive stationary, partially occluded objects as connected units (Experiments 1 and 2) with specific appearances (Experiment 3). In each experiment, the infants saw 2 test events involving what appeared to adults to be a tall rectangular object whose middle portion was hidden behind a narrow screen. During the test events, the screen alternately uncovered and covered the object. In Experiments 1 and 2, removal of the screen revealed either a single, connected rectangle (complete object event) or an interrupted rectangle with a gap where the screen had been (broken object event). In Experiment 3, removal of the screen revealed either a rectangle (rectangle event) or a cross-shaped object (cross-shape event). The pattern of infants' looking times at these events suggest that they perceive the unity of the partially occluded object by 6.5 months of age but did not perceive the form of the hidden part of the object until 8 months. The results of baseline control conditions support this interpretation.     

12-month-olds' phonotactic knowledge guides their word-object mappings

This study examined whether 12‐month‐olds will accept words that differ phonologically and phonetically from their native language as object labels in an associative learning task. Sixty infants were presented with sets of English word–object (N = 30), Japanese word–object (N = 15), or Czech word–object (N = 15) pairings until they habituated. Infants associated CVCV English, CCVC English, and CVCV Japanese words, but not CCVC Czech words, with novel objects. These results demonstrate that by 12 months of age, infants are beginning to apply their language‐specific knowledge to their acceptance of word forms. That is, they will not map words that violate the phonotactics of their native language to objects.     

Visual Constancies Amidst Changes in Handled Objects for 5- to 24-Month-Old Infants

Manual skills slowly develop throughout infancy and have been shown to create clear views of objects that provide better support for visually sustained attention, recognition, memory, and learning. These clear views may coincide with the development of manual skills, or that social scaffolding supports clear viewing experiences like those generated by toddlers during active object exploration. This study used a head-mounted eye tracker to record 5- to 24-month-olds’ object views during repeated mother-infant play sessions (Ns = 18). Results show an early beginning of scaffolding in which parents generate views similar to those of older infants and toddlers, resulting in increased fixations to objects. The finding implicates parents as early scaffolders of object attention and learning.