Perceiving the Affordance of Contact in Fourand Five-Month-Old Infants

The focus of this study was on the ability of infants to perceive whether an object is positioned at a distance that would make contact possible. As a toy was presented, sometimes within and sometimes beyond reach, the initiation of reaching and leaning forward was scored. Infants were divided into leaning and nonleaning groups. Both leaning and nonleaning 5-month-olds changed their behavior dramatically when the object was placed beyond, as opposed to within, reach. The nonleaners showed a decline in reaching when this boundary for contact was crossed. The "leaners" did not; rather, they began to lean forward. These results suggest that 5-month-olds use information for the affordance of contact. 4-month-olds provided less evidence that arm length regulates reaching. 5-month-old infants acted as if they not only had some sensitivity to the absolute distance of an object but also to the effect that leaning forward has on their ability to make contact with a distant object.     

Integration of Sequential Information for Shape Perception by Infants: A Developmental Study

Perception of form by spatiotemporal integration was investigated in 3 experiments. In the first, infants aged 8, 10, and 12 months were tested using a novelty-preference procedure to determine the earliest age at which recognition of rectilinear and curvilinear form occurred. Infants were shown a light-point tracing of the outline of a figure, followed by simultaneous presentation of 2 test objects, one of the same shape as the tracing and one of a different shape. The tracing was double the size of the test objects. Only infants in the oldest group responded selectively by looking longer at the object of different shape. In the second experiment with 12-month-old infants only, it was shown that recognition of rectilinear, but not curvilinear, form occurred despite a difference in the orientation and size of tracing and object. Computer-generated tracings were used in the final experiment to compare form recognition for 2D and 3D stimuli. Selective responding occurred only for the latter. These findings show that by 12 months infants perceive the correspondence between the figural properties of a tracing and its extended form, but that this perception is dependent on the provision of depth cues.     

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.     

Orientation Effects in the Development of Linear Object Tracking in Early Infancy

Infants' oculomotor tracking develops rapidly but is poorer when there are horizontal and vertical movement components. Additionally, persistence of objects moving through occlusion emerges at 4 months but initially is absent for objects moving obliquely. In two experiments, we recorded eye movements of thirty-two 4-month-old and thirty-two 6-month-old infants (mainly Caucasian-White) tracking horizontal, vertical, and oblique trajectories. Infants tracked oblique trajectories less accurately, but 6-month olds tracked more accurately such that they tracked oblique trajectories as accurately as 4-month olds tracked horizontal and vertical trajectories. Similar results emerged when the object was temporarily occluded. Thus, 4-month olds’ tracking of oblique trajectories may be insufficient to support object persistence, whereas 6-month olds may track sufficiently accurately to perceive object persistence for all trajectory orientations.     

Is Visually Guided Reaching in Early Infancy a Myth?

The issue examined was whether infants require sight of their hand when first beginning to reach for, contact, and grasp objects. 7 infants were repeatedly tested between 6 and 25 weeks of age. Each session consisted of 8 trials of objects presented in the light and 8 trials of glowing or sounding objects in complete darkness. Infants first contacted the object in both conditions at comparable ages (mean age for light, 12.3 weeks, and for dark, 11.9 weeks). Infants first grasped the object in the light at 16.0 weeks and in the dark at 14.7 weeks, a nonsignificant difference. Once contact was observed, infants continued to touch and grasp the objects in both light and dark throughout all sessions. Because infants could not see their hand or arm in the dark, their early success in contacting the glowing and sounding objects indicates that proprioceptive cues, not sight of the limb, guided their early reaching. Reaching in the light developed in parallel with reaching in the dark, suggesting that visual guidance of the hand is not necessary to achieve object contact either at the onset of successful reaching or in the succeeding weeks.     

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.     

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.     

Inability of five-month-old infants to retrieve a contiguous object: a failure of conceptual understanding or of control of action?

Infants of 5 to 6 months of age can retrieve a free-standing object, but fail to retrieve the same object from atop a slightly larger object. The accepted explanation has been that the infants do not understand that an object continues to exist independently when placed upon another. Predictions based on that explanation were tested against the hypothesis that infants' problem consists of lack of precision in visually guided reaching and lack of ability to inhibit reflexive reactions to touch. Twelve infants each at 5 and 7 months of age were tested on 16 trials. More 5-month-olds succeeded, in less time, and with fewer touches to an edge of the base, on trials more forgiving of an imprecise reach than on less forgiving trials. Success in retrieving objects close in size and fully contiguous with their bases was seen even at 5 months when the demands on skill in reaching were reduced. It is proposed that when 5-month-old infants fail to retrieve one object placed upon another, it is not because of a lack of conceptual understanding, but because they lack the skill to reach to the top object without accidentally touching an edge of the base en route.     

The Transition to Reaching: Mapping Intention and Intrinsic Dynamics

The onset of directed reaching demarks the emergence of a qualitatively new skill. In this study we asked how intentional reaching arises from infants' ongoing, intrinsic movement dynamics, and how first reaches become successively adapted to the task. We observed 4 infants weekly in a standard reaching task and identified the week of first arm-extended reach, and the 2 weeks before and after onset. The infants first reached at ages ranging from 12 to 22 weeks, and they used different strategies to get the toy. 2 infants, whose spontaneous movements were large and vigorous, damped down their fast, forceful movements. The 2 quieter infants generated faster and more energetic movements to lift their arms. The infants modulated reaches in task-appropriate ways in the weeks following onset. Reaching emerges when infants can intentionally adjust the force and compliance of the arm, often using muscle coactivation. These results suggest that the infant central nervous system does not contain programs that detail hand trajectory, joint coordination, and muscle activation patterns. Rather, these patterns are the consequences of the natural dynamics of the system and the active exploration of the match between those dynamics and the task.     

Crossing the midline: limits of early eye-hand behavior.

The development of the ability to extend the hand across the body midline to contact a visually presented object was examined in 48 normal, full-term, 9--20-week infants. One of the infant's arms was restrained while the behavior of the contralateral, unrestrained arm was observed. Results indicate that infants can first contact objects placed in front of the ipsilateral shoulder, then at the body midline, and later in front of the contralateral shoulder. Between 9 and 17 weeks, success at contacting objects at the midline progressed from 33% to 93%. During this interval, the success in contacting objects presented in front of the contralateral shoulder increased from 0% to 71%. By 18--20 weeks, all infants contacted objects in all three positions. These findings indicate that visually directed hand extension and reaching skills progress from the ipsilateral to include the bilateral and later the contralateral domains. The results are considered in regard to the development of bilateral coordination and complementarity.     

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.     

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.     

Object Permanence in Young Infants: Further Evidence

Recent evidence suggests that 4.5- and even 3.5-month-old infants realize that objects continue to exist when hidden. The goal of the present experiments was to obtain converging evidence of object permanence in young infants. Experiments were conducted using paradigms previously used to demonstrate object permanence in 5.5-month-old infants and 6.5-month-old infants. In one experiment, 3.5-month-old infants watched a short or a tall carrot slide along a track. The track's center was hidden by a screen with a large window in its upper half. The short carrot was shorter than the window's lower edge and so did not appear in the window when passing behind the screen; the tall carrot was taller than the window's lower edge and hence should have appeared in the window but did not. The infants looked reliably longer at the tall than at the short carrot event, suggesting that they (a) represented the existence, height, and trajectory of each carrot behind the screen and (b) expected the tall carrot to appear in the screen window and were surprised that it did not. Control trials supported this interpretation. In another experiment, 4.0-month-old infants saw a toy car roll along a track that was partly hidden by a screen. A large toy mouse was placed behind the screen, either on top or in back of the track. The female infants looked reliably longer when the mouse stood on top as opposed to in back of the track, suggesting that they (a) represented the existence and trajectory of the car behind the screen, (b) represented the existence and location of the mouse behind the screen, and (c) were surprised to see the car reappear from behind the screen when the mouse stood in its path. A second experiment supported this interpretation. The results of these experiments provide further evidence that infants aged 3.5 months and older are able to represent and to reason about hidden objects.     

Infants Use Compression Information to Infer Objects’ Weights: Examining Cognition,Exploration, and Prospective Action in a Preferential‐Reaching Task

The present research used a preferential‐reaching task to examine whether 9‐ and 11‐month‐olds (n = 144) could infer the relative weights of two objects resting on a soft, compressible platform. Experiment 1 established that infants reached preferentially for the lighter of 2 boxes. In Experiments 2–4, infants saw 2 boxes identical except in weight resting on a cotton wool platform. Infants reached prospectively for the lighter box, but only when their initial exploratory activities provided critical information. At 11 months, infants succeeded as long as they first determined that the platform was compressible; at 9 months, infants succeeded only if they also explored the boxes and thus had advance knowledge that they differed in weight.     

Development of the ability to use recall to guide action, as indicated by infants' performance on AB

25 infants were tested every 2 weeks on the AB Object Permanence Task devised by Piaget, from the age when they first reached for a hidden object until they were 12 months. The delay between hiding and retrieval necessary to produce the AB error increased continuously throughout this period at an average rate of 2 sec/month, from under 2 sec at 7 1/2 months to over 10 sec by 12 months. All children displayed the AB error repeatedly over the months of testing. Large between-children differences in delay needed for the AB error were found at each age. Girls tolerated longer delays than boys. The characteristic pattern to the AB error did not vary over age or sex. Range of delay producing the AB error in any child was small. Errors disappeared when delays were reduced by 2-3 sec, and reaching became random or severely perseverative when delays were increased 2-3 sec above the level producing AB error. AB provides an index of the ability to carry out an intention based on stored information despite a conflicting habitual tendency.     

Postural,Visual, and Manual Coordination in the Development of Prehension

We investigated the real-time cascade of postural, visual, and manual actions for object prehension in 38 6- to 12-month-old infants (all independent sitters) and eight adults. Participants’ task was to retrieve a target as they spun past it at different speeds on a motorized chair. A head-mounted eye tracker recorded visual actions and video captured postural and manual actions. Prehension played out in a coordinated sequence of postural–visual–manual behaviors starting with turning the head and trunk to bring the toy into view, which in turn instigated the start of the reach. Visually fixating the toy to locate its position guided the hand for toy contact and retrieval. Prehension performance decreased at faster speeds, but quick planning and implementation of actions predicted better performance.     

How infants use vision for grasping objects

The role of vision was examined as infants prepared to grasp horizontally and vertically oriented rods. Hand orientation was measured prior to contact to determine if infants differentially oriented their hands relative to the object's orientation. Infants reached for rods under different lighting conditions. Three experiments are reported in which (1) sight of the hand was removed (N = 12), (2) sight of the object was removed near the end of the reach (N = 40, including 10 adults), and (3) sight of the object was removed prior to reach onset (N = 9). Infants differentially oriented their hand to a similar extent regardless of lighting condition and similar to control conditions in which they could see the rod and hand throughout the reach. In preparation for reaching, infants may use the current sight of the object's orientation, or the memory of it, to orient the hand for grasping; sight of the hand had no effect on hand orientation.     

It clicks when it is rolled and it squeaks when it is squeezed: what 10-month-old infants learn about object function

Function has been considered important in numerous literatures in the study of cognitive development, yet little is known about what and how infants learn about function. Five experiments examined what 10-month-old infants (N=80) learn about functions that involve a sound produced when an object is acted on. Infants habituated to a single object (Experiment 1) or multiple objects that performed the same function (Experiment 2) learned both the actions and the sounds. Infants did not appear to learn relations between actions and sounds (Experiment 3) or appearances and sounds (Experiment 4), although they did learn the relations between appearances and actions (Experiment 5). These results are discussed in terms of how infants learn about object function.     

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.