Infants’ ability to track and reach for temporarily occluded objects

• Six-month-old infants were presented with a moving object that temporarily became invisible. The object moved on a horizontal path and was made invisible for either 400, 800 or 1,200 ms before being within reach. Two kinds of events were used to make the object invisible: blackout of the room lights and occlusion behind a screen. First, infants saw 6 trials of the fully visible motion, then 12 trials of a temporarily invisible motion and finally 6 trials of the fully visible motion again. Each infant was presented with only one of the 6 experimental conditions. The results show that reaching is much more severely affected by a eriod of temporary non-visibility than tracking. The effects of the two modes of non-visibility were rather different. In general, lackout deteriorated tracking and made the gaze lag at reappearance. It inhibited reaching but this effect attenuated with experience. onger periods of blackout deteriorated tracking and reaching more. Compared to blackout, occlusion had both a facilitating and an inhibiting effect on infants’ actions. Tracking had less tendency to lag but reaching showed more severe inhibition. The results are discussed in terms of graded representations. Furthermore, it is argued that an occluder facilitates tracking by providing information of where the moving object becomes visible again and it inhibits reaching by interfering with the representation of the object behind the occluder.

Ämnesord

SAMHÄLLSVETENSKAP  -- Psykologi -- Psykologi (hsv//swe)

SOCIAL SCIENCES  -- Psychology -- Psychology (hsv//eng)

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