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Four- and Five-month-olds Can Track Briefly Occluded Objects

Evidence that four- and five-month-olds can track momentarily occluded objects comes from studies using habituation, violation-of-expectations, anticipatory looking and the completion of an action directed to a fully occluded object that was prepared in advance of the object being fully occluded.

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A wide range of evidence suggests that four- and five-month-olds can track briefly occluded objects.

Such evidence comes from infants’ reactions to a range of different scenarios. Some scenrios involve a comparision between the number of objects (e.g. Spelke, Kestenbaum, Simons, & Wein, 1995), others involve infants’ abilities to track the causal effects of unperceived objects (e.g. Baillargeon, 1987), while others require infants to track properties such as the shape and size of unperceived objects (e.g. Wang, Baillargeon, & Brueckner, 2004), or to remember the location of a hidden object (e.g. Wilcox, Nadel, & Rosser, 1996).

The evidence also comes from studies using a variety of different methods. These include habituation (e.g. Spelke et al., 1995), violation-of-expectation (e.g. Wang et al., 2004), and anticipatory looking (e.g. Rosander & Hofsten, 2004; Bertenthal, Gredebäck, & Boyer, 2013).

How do infants track briefly occluded objects? An early idea was that infants’ earliest abilities involved knowledge of physical objects:

‘objects are conceived: Humans come to know about an object’s ... boundaries ... in ways like those by which we come to know about its material composition or its market value.’ (Spelke, 1998, p. 198)

One prediction of this idea is that infants should be able to search for briefly occluded objects. Because that prediction has been falsified (e.g. Shinskey & Munakata, 2001), the idea should probably be rejected.

We therefore need alternative ideas about how infants track briefly occluded objects ...


habituation : Habituation is used to test hypotheses about which events are interestingly different to an infant. In a habituation experiment, infants are shown an event repeatedly until it no longer holds their interest, as measured by how long they look at it. The infants are then divided into two (or more) groups and each group is shown a new event. How much longer do they look at the new event than at the most recent presentation of the old event? This difference in looking times indicates dishabituation, or the reawakening of interest. Given the assumption that greater dishabituation indicates that the old and new events are more interestingly different to the infant, evidence from patterns of dishabituation can sometimes support conclusions about patterns in how similar and different events are to infants.
tracking an attribute : For a process to track an attribute or thing is for the presence or absence of the attribute or thing to make a difference to how the process unfolds, where this is not an accident. (And for a system or device to track an attribute is for some process in that system or device to track it.)
Tracking an attribute or thing is contrasted with computing it. Unlike tracking, computing typically requires that the attribute be represented.
violation-of-expectation : Violation-of-expectation experiments test hypotheses about what infants expect by comparing their responses to two events. The responses compared are usually looking durations. Looking durations are linked to infants’ expectations by the assumption that, all things being equal, infants will typically look longer at something which violates an expectation of theirs than something which does not. Accordingly, with careful controls, it is sometimes possible to draw conclusions about infants’ expectations from evidence that they generally look longer at one event than another.


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