[Show abstract][Hide abstract] ABSTRACT: Advocates of the "continuity hypothesis" have argued that innate non-verbal counting principles guide the acquisition of the verbal count list (Gelman & Galistel, 1978). Some studies have supported this hypothesis, but others have suggested that the counting principles must be constructed anew by each child. Defenders of the continuity hypothesis have argued that the studies that failed to support it obscured children's understanding of counting by making excessive demands on their fragile counting skills. We evaluated this claim by testing two-, three-, and four-year-olds both on "easy" tasks that have supported continuity and "hard" tasks that have argued against it. A few noteworthy exceptions notwithstanding, children who failed to show that they understood counting on the hard tasks also failed on the easy tasks. Therefore, our results are consistent with a growing body of evidence that shows that the count list as a representation of the positive integers transcends pre-verbal representations of number.
[Show abstract][Hide abstract] ABSTRACT: Infants aged 4 and 6 months were presented with events in which a person acted so as to set another person, or an inanimate object, in motion. In one condition, the actor spoke to the person (natural) or inanimate object (unnatural); in the other condition, the actor grasped and manipulated the person (unnatural) or object (natural). Six-month-old infants looked reliably longer at the natural actions than at the unnatural actions. A follow-up experiment revealed that their preference depended on the naturalness of the human actions themselves, not on the features or motions of the person or object that was acted upon. Looking preferences at 4 months were equivocal, consistent with the thesis that sensitivity to the natural actions develops over the first 6 months of age. We discuss these findings in relation to the development of social understanding, social gaze, and visual exploration.
Journal of Cognition and Development 11/2004; 5(4):399-426. DOI:10.1207/s15327647jcd0504_1 · 1.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Four-month-old infants were allowed to manipulate, without vision, two rings attached to a bar that permitted each ring to undergo rotary motion against a fixed surface. In different conditions, the relative motions of the rings were rigid, independent, or opposite, and they circled either the same fixed point outside the zone of manipulation or spatially separated points. Infants' perception of the ring assemblies were affected by the nature of the rotary motion in two ways. First, infants perceived a unitary object when the felt ends of the object underwent a common, rigid rotary motion; perception of object unity was stronger in this condition than when the ends underwent either independent or opposite rotary motions. Second, infants perceived two distinct objects when the felt ends of the objects underwent independent rotary motions that centred on distinct fixed points. Perception of the distinctness of the objects was less clear when the ends underwent opposite or independent rotary motions that centred on a common fixed point. These findings provide the first evidence that infants are sensitive to rotary motion patterns and can extrapolate a global pattern of rigid motion from the distinct, local velocities that they produce and experience at their two hands.
The Quarterly Journal of Experimental Psychology A 05/2004; 57(3):523-38. DOI:10.1080/02724980343000378
[Show abstract][Hide abstract] ABSTRACT: Two experiments assessed ordinal numerical knowledge in 2- and 3-year-old children and investigated the relationship between ordinal and verbal numerical knowledge. Children were trained on a 1 vs 2 comparison and then tested with novel numerosities. Stimuli consisted of two trays, each containing a different number of boxes. In Experiment 1, box size was held constant. In Experiment 2, box size was varied such that cumulative surface area was unrelated to number. Results show children as young as 2 years of age make purely numerical discriminations and represent ordinal relations between numerosities as large as 6. Children who lacked any verbal numerical knowledge could not make ordinal judgments. However, once children possessed minimal verbal numerical competence, further knowledge was entirely unrelated to ordinal competence. Number may become a salient dimension as children begin to learn to count. An analog magnitude representation of number may underlie success on the ordinal task.
[Show abstract][Hide abstract] ABSTRACT: Two studies exploited a new manual search methodology to assess the bases on which 10- to 12-month-olds individuate objects. Infants saw 1 or 2 objects placed inside an opaque box, into which they could reach. Across conditions, the information specifying 2 objects differed. The dependent measures reflected persistence of reaching into a box that was empty regardless of whether an object should have remained. Success consists of little reaching after all objects are removed and persistent reaching for an object not yet retrieved. Given spatiotemporal information for 2 objects, both age groups succeeded. Given only property or kind information, only 12-month-olds succeeded. Despite disparate information-processing demands, this pattern converges with looking time data (Xu & Carey, 1996; Xu, Carey, & Welch, 1999), suggesting a developmental change orthogonal to that of executive function. This change may reflect the emergence of kind representations.
Journal of Cognition and Development 08/2000; 1(3):249-280. DOI:10.1207/S15327647JCD0103_1 · 1.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Preferential looking experiments investigated 5- and 8-month-old infants' perception and understanding of the motions of a shadow that appeared to be cast by a ball upon a box. When all the surfaces within the display were stationary, infants looked reliably longer when the shadow moved than when the shadow was stationary, indicating that they detected the shadow and its motion. In further experiments, however, infants' looking was not consistent with a sensitivity to the shadow's natural motion: They looked longer at natural events in which the shadow moved with the ball or remained at rest under the moving box than at unnatural events in which the shadow moved with the box or remained at rest under the moving ball. These findings suggest that infants overextend to shadows a principle that applies to material objects: Objects move together if and only if they are in contact. In a final experiment, infants were habituated to a moving shadow that repeatedly violated one aspect of the contact principle. In a subsequent test they failed to infer that the shadow would violate another aspect of the contact principle. Instead, they appeared to suspend all predictions concerning the behavior of the shadow.
Cognitive Development 10/1998; 13(4-13):387-419. DOI:10.1016/S0885-2014(98)90001-6 · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 3 experiments investigated 5-month-old infants' perception of an object whose center was fully occluded and whose ends were visible only in succession. Infants perceived this object as one connected whole when the ends of the object underwent a common motion behind the occluder, but not when the ends were stationary. Although infants perceived the connectedness of the object, they did not appear to perceive the object's shape. These findings suggest (a) that young infants are capable of integrating information over time to perceive object unity but not object form, (b) that young infants perceive object unity in accord with basic constraints on object motion, and (c) that a common process underlies infants' perception of objects that are fully visible, objects that are partly occluded, and objects that move fully out of view.
Child Development 01/1997; 67(6):2621-40. DOI:10.2307/1131743 · 4.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: infants' perception of object boundaries / infants' perception of object identity / developmental changes in object perception / from infants to adults (PsycINFO Database Record (c) 2012 APA, all rights reserved)