Examining the role of social cues in early word learning.

Infants watched a video of an adult pointing towards two different objects while hearing novel labels. Analyses indicated that 14- and 18-month-olds looked longer at the target object, but only 18-month-olds showed word learning. The results suggest that different types of social cues are available at different ages.

Early information processing among infants with and without spina bifida.

This study focuses on the development of early visual information processing among infants with spina bifida (SB) compared to typically developing infants using the habituation-dishabituation paradigm. Analyses were conducted in two stages. First infants were evaluated to determine if 18-month old infants (SB=47; Control=40) differed in their ability to shift attention and habituate to two female faces, as well as their responses to composite and novel stimuli. Second, relations between these variables and infant motor and mental functioning were evaluated. The results of the study indicated that difficulties with visual attention skills can be detected as early as 18 months of age among infants with SB. Infants with SB differed significantly from controls on attention getting. Although there were no differences found on habituation and composite tasks, infants with SB differed significantly from controls on their ability to dishabituate. Implications are discussed.

Labels can override perceptual categories in early infancy.

An extensive body of research claims that labels facilitate categorisation, highlight the commonalities between objects and act as invitations to form categories for young infants before their first birthday. While this may indeed be a reasonable claim, we argue that it is not justified by the experiments described in the research. We report on a series of experiments that demonstrate that labels can play a causal role in category formation during infancy. Ten-month-old infants were taught to group computer-displayed, novel cartoon drawings into two categories under tightly controlled experimental conditions. Infants were given the opportunity to learn the two categories under four conditions: Without any labels, with two labels that correlated with category membership, with two labels assigned randomly to objects, and with one label assigned to all objects. Category formation was assessed identically in all conditions using a novelty preference procedure conducted in the absence of any labels. The labelling condition had a decisive impact on the way infants formed categories: When two labels correlated with the visual category information, infants learned two categories, just as if there had been no labels presented. However, uncorrelated labels completely disrupted the formation of any categories. Finally, consistent use of a single label across objects led infants to learn one broad category that included all the objects. These findings demonstrate that even before infants start to produce their first words, the labels they hear can override the manner in which they categorise objects.

Modeling the Development of Infant Categorization.

Research on infant categorization has made remarkable progress since the first studies were reported in the late 1970s (e.g., Cohen & Caputo, 1978; Cohen & Strauss, 1977; Strauss, 1979). This progress is evident in a recent volume on early categorization and concept acquisition (Rakison & Oakes, 2003), the first half of which is devoted entirely to theory and research on infant categorization. Even in the early days of such research an important distinction was made between demonstration-oriented studies and process-oriented studies (Cohen & Younger, 1983; Younger & Cohen, 1985). Demonstration studies simply presented infants with established category items (by adult standards) such as pictures of stuffed animals, faces, dogs, cats, animals, or vehicles and examined whether infants would generalize their responding to novel members of the same category. Process studies, on the other hand, presented infants with novel categories and manipulated feature values of category items to examine the mechanisms underlying infant category acquisition.

Modeling Age Differences in Infant Category Learning.

We used an encoder version of cascade correlation to simulate Younger and Cohen's (1983, 1986) finding that 10-month-olds recover attention on the basis of correlations among stimulus features, but 4- and 7-month-olds recover attention on the basis of stimulus features. We captured these effects by varying the score threshold parameter in cascade correlation, which controls how deeply training patterns are learned. When networks learned deeply, they showed more error to uncorrelated than to correlated test patterns, indicating that they abstracted correlations during familiarization. When prevented from learning deeply, networks decreased error during familiarization and showed as much error to correlated as to uncorrelated tests but less than to test items with novel features, indicating that they learned features but not correlations among features. Our explanation is that older infants learn more from the same exposure than do younger infants. Unlike previous explanations that postulate unspecified qualitative shifts in processing with age, our explanation focuses on quantitatively deeper learning with increasing age. Finally, we provide some new empirical evidence to support this explanation.

Six-month-old infants' categorization of containment spatial relations.

Six-month-old infants' ability to form an abstract category of containment was examined using a standard infant categorization task. Infants were habituated to 4 pairs of objects in a containment relation. Following habituation, infants were tested with a novel example of the familiar containment relation and an example of an unfamiliar relation. Results indicate that infants look reliably longer at the unfamiliar versus familiar relation, indicating that they can form a categorical representation of containment. A second experiment demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. Together, the results indicate that by 6 months, infants can recognize a containment relation from different angles and across different pairs of objects.

Eight-Month-Old Infants' Perception of Possible and Impossible Events.

This study investigated 8-month-old infants' perception of object permanence in an extension of the rotating screen studies by Baillargeon (1987) and Baillargeon, Spelke, and Wasserman (1985). Using computer-animated stimuli similar to the "live" stimuli used by Baillargeon and her colleagues (Baillargeon, 1987; Baillargeon et al., 1985), 48 8-month-old infants were habituated to 1 of 4 computer-animated events and then tested on all 4 events. The events involved a screen that rotated in either a 180° or 120° arc*** and a block that either was sitting in the path of the rotating screen or absent from the event. The results provided no evidence that infants responded on the basis of the possibility or impossibility of the events as claimed by Baillargeon and her colleagues, but instead indicated that the infants responded on the basis of perceptual novelty. These results are consistent with the findings of Schilling (this issue) and Bogartz, Shinskey, and Schilling (this issue). Taken together, along with the findings of Rivera, Wakeley, and Langer (1999), these more recent findings suggest that Baillargeon's (1987; Baillargeon et al., 1985) results should not be interpreted as definitive evidence of object permanence in very young infants.