| 1. |
- Fagard, Jacqueline, et al.
(författare)
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Reaching and grasping a moving object in 6-, 8-, and 10-month-old infants : Laterality and performance
- 2009
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Ingår i: Infant Behavior and Development. - : Elsevier BV. - 0163-6383 .- 1879-0453. ; 32:2, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- The goal of this study was to investigate some of the visuo-motor factors underlying an infant's developing ability to grasp a laterally-moving object. In particular, hand preference, midline crossing, and visual-field asymmetry were investigated by comparing performance as a function of the object's direction of motion. We presented 6-, 8-, and 10-month-old infants with a graspable object, moving in a circular trajectory in the horizontal plane. Six-month-old infants reached for the object with the ipsilateral hand and grasped it with the contralateral hand. Eight-month-old infants showed a strong right-hand bias for both reaching and grasping. Ten-month-old infants showed a greater diversity of strategy use including bimanual and successful ipsilateral grasping following ipsilateral reaching in both directions of motion. Thus, motor constraints due to spatial compatibility, hand preference and bimanual coordination (but not midline crossing) must be taken into account to understand age differences in grasping a moving object.
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| 2. |
- Hespos, Sue, et al.
(författare)
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Occlusion Is Hard : Comparing Predictive Reaching for Visible and Hidden Objects in Infants and Adults
- 2009
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Ingår i: Cognitive science. - : Wiley. - 0364-0213 .- 1551-6709. ; 33:8, s. 1483-1502
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Tidskriftsartikel (refereegranskat)abstract
- Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed, but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.
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| 3. |
- Munakata, Yuko, et al.
(författare)
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When it helps to occlude and obscure : 6-month-olds' predictive tracking of moving toys
- 1996
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Ingår i: Infant Behavior and Development. - 0163-6383 .- 1879-0453. ; 19:Suppl. 1, s. 639-639
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Tidskriftsartikel (refereegranskat)abstract
- What do infants know about hidden objects’? Previous research suggests that the answer depends on how the objects are hidden. For instance, infants appear to reach for toys in the dark (Clifton, Rochat, Litovsky, & Penis, 1991; Hood & Willatts, 1986) before they reach for toys occluded in the light. However, these experiments have not compared directly toys occluded in the light and by darkness. The current experiment tests infants under both conditions in the same paradigm. In addition, the experiment introduces a combined ccluderdarkness condition to test two distinct explanations for a possible advantage in the dark. First, infants may have knowledge about hidden objects but cannot act on it for occluder-specific reasons (e.g., means-ends deficits, beliefs about the whether the object is accessible). Second, infants may have graded representations of occluded objects that can be more easily maintained in the face of global darkness than with the direct visual interference of an occluder. Counterintuitive results from the current experiment provide evidence for both representational and occluder-specific effects.
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| 4. |
- von Hofsten, Claes, et al.
(författare)
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Object representation and predictive action in infancy
- 2000
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Ingår i: Developmental Science. - Oxford, UK and Malden, USA : Blackwell Publishers Ltd.. - 1363-755X .- 1467-7687. ; 3:2, s. 193-205
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that 6-month-old infants extrapolate object motion on linear paths when they act predictively on fully visible moving objects but not when they observe partly occluded moving objects. The present research probed whether differences in the tasks presented to infants or in the visibility of the objects account for these findings, by investigating infants’ predictive head tracking of a visible object that moves behind a small occluder. Six-month-old infants were presented with an object that moved repeatedly on linear or nonlinear paths, with an occluder covering the place where all the paths intersected. The first time infants viewed an object’s motion, their head movements did not anticipate either linear or nonlinear motion, but they quickly learned to anticipate linear motion on successive trials. Infants also learned to anticipate nonlinear motion, but this learning was slower and less consistent. Learning in all cases concerned the trajectory of the object, not the specific locations at which the object appeared. These findings suggest that infants form object representations that are weakly biased toward inertial motion and that are influenced by learning. The findings accord with the thesis that a single system of representation underlies both predictive action and perception of object motion, and that occlusion reduces the precision of object representations.
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| 5. |
- von Hofsten, Claes, et al.
(författare)
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Predictive action in infancy : tracking and reaching for moving objects
- 1998
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Ingår i: Cognition. - : Elsevier. - 0010-0277 .- 1873-7838. ; 67:3, s. 255-285
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Tidskriftsartikel (refereegranskat)abstract
- Because action plans must anticipate the states of the world which will be obtained when the actions take place, effective actions depend on predictions. The present experiments begin to explore the principles underlying early-developing predictions of object motion, by focusing on 6-month-old infants' head tracking and reaching for moving objects. Infants were presented with an object that moved into reaching space on four trajectories: two linear trajectories that intersected at the center of a display and two trajectories containing a sudden turn at the point of intersection. In two studies, infants' tracking and reaching provided evidence for an extrapolation of the object motion on linear paths, in accord with the principle of inertia. This tendency was remarkably resistant to counter-evidence, for it was observed even after repeated presentations of an object that violated the principle of inertia by spontaneously stopping and then moving in a new direction. In contrast to the present findings, infants fail to extrapolate linear object motion in preferential looking experiments, suggesting that early-developing knowledge of object motion, like mature knowledge, is embedded in multiple systems of representation.
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