Browsing by Subject "Infant perception"
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Item Infant number perception : a developmental approach(2009-05) Brez, Caitlin Christine; Cohen, Leslie B.Infant number perception is a topic that has been studied for many years, but many questions remain regarding what cues infants use to make these discriminations, when and how these abilities develop, and what systems are responsible for infants’ number processing. In the domain of small number perception (quantities less than four), researchers have studied the effects of continuous extent on infants’ number discrimination (Clearfield & Mix, 1999; 2001). While evidence exists that infants can use continuous extent to make discriminations, it is not clear how much influence continuous extent has on infants’ behavior in these tasks. Another issue that has not been thoroughly addressed is the role of featural information in number discrimination. Few studies exist in which featural information is manipulated so that this issue can be addressed. The current study was designed to address these issues as well as to study infant number discrimination from a developmental perspective across several ages. Infants, aged 9-, 11-, and 13-months, completed a categorization task in which they were habituated to pictures of objects (e.g. bowl, tree, shoe) in either groups of two or groups of three. They saw four different sets of objects throughout habituation. In the test phase, infants saw both new and old objects in both groups of two and three. The 9-month-olds discriminated number independent of whether the object was familiar or novel. In contrast, the 11- month-olds appeared to discriminate between the familiar and novel objects. And, the 13-month-olds exhibited a combination of these two patterns; they discriminated between the familiar and novel object when the number of objects was familiar, but not when the number of objects was novel. These data suggest that number is an easily abstracted construct and that early number representations do not contain any featural information. As infants get older, they begin to incorporate featural information into their representations, but they do so in a step-wise fashion, as demonstrated by the 13-month-olds. Therefore, featural information does not appear to be important for small number discrimination at early ages, but infants do begin to integrate featural information as they develop.Item Manipulating spatial frequency to understand global and local information processing in 7-month-old infants(2009-08) Gora, Keith Matthew; Cohen, Leslie B.It has been shown that infants build representations of their visual world by forming relations among its parts. However little is known about how they select the parts to relate. One possibility is that while constructing their visual world part by part they are also decomposing it, using finer and finer parts. One way to test this theory is to simply control the parts infants see. This easiest way to do this is to filter real life objects of their high and low spatial frequencies. High spatial frequencies provide information about the smaller parts where as low spatial frequencies provide information about the larger ones. By removing high or low spatial frequency we can control the coarseness of their representation and ultimately determine the level at which they function best. The present study examined infants’ ability to use high and low spatial frequencies to discriminate between objects. Infants were habituated and tested using a combination of high and low spatial frequency images. Only infants experiencing a consistent spatial frequency across habituation and test were able to discriminate between objects. Infants were also better at discriminating between objects containing high spatial frequencies. In a second study designed to be more true to life, infants were habituated to broadband images and tested using high or low spatial frequencies. This time infants did not discriminate between objects but they did look longer at low spatial frequency information than at the high. From these findings we can conclude that infants use both high and low spatial frequency information when discriminating objects, and that in certain cases one frequency may become more important than the other. The spatial frequency they use may be dependent on the context of the task. Numerous studies have shown that adults prioritize high and low spatial frequency information depending on how fast they want to process the object, the amount of detail they require, and whether they used high or low spatial frequency information during previous experiences. Infants may be similar. At times they may emphasize low spatial frequency information and the big picture. At other times they may emphasize high spatial frequency information and the detail. More studies examining how infants select information for processing are necessary and spatial frequency will likely to be an important tool in the investigation.