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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.

Infant visual attention and habituation were examined with a procedure providing independent assessment of an infant's latency of orienting to a pattern (attention getting) and his subsequent fixation of that pattern (attention holding). 18 male and 18 female, 17-week-old infants were given 2 trials with a red circle, 16 trials with either a 2 times 2, 8 times 8, or 24 times 24 checkerboard pattern, then 2 more red-circle trials. The major results were that habituation occurred in fixation time with males habituating more than females, and that a general decrease occurred in latency with females selectively increasing or decreasing their latency depending upon the pattern they had previously seen. These results indicated the necessity of separating attention-getting from attention-holding measures and that both sexes remembered something about the visual patterns but demonstrated that memory differently.

The ability of 18-, 24-, and 30-week-old infants to learn conceptual categories regarding adult female faces was examined using a habituation paradigm. Little evidence for conceptual categorization occurred at 18 or 24 weeks, but at 30 weeks infants learned to respond to "a specific female face regardless of orientation" and to "female faces in general."

2 experiments with 18-week-old infants employed an interference paradigm to study infant visual memory. The infants were habituated to a repeated stimulus, given several trials with 1 or more interpolated stimuli, and then tested for recognition of the original stimulus. In Experiment 1, both amount of exposure and the similarity of the potentially interfering material to the original habituation stimulus were manipulated. Neither produced a significant interference effect, although some effect may have been shown by subjects who habituated to the interference stimult did demonstrate more clearly long-term retention of the originally remembered material. It was concluded from both studies that infant visual memory is a robust phenomenon, relatively immune to interference under most conditions.

The perception of relational information such as the correlation or co-occurrence among features should play a central role in abilities ranging from the perception and recognition of a simple pattern or object to the formation of a category. 4 experiments were conducted to examine developmental change in 4-, 7-, and 10-month-old infants' perception of correlations among attributes. The results suggested a developmental progression in infants' processing of simple correlational information, ranging from the processing of independent featural information only at 4 months, the perception of relations among features of a single pattern at 7 months, to the abstraction of invariant relations from a category at 10 months.

To investigate Piaget's theory of object concept development, a series of 6 tasks was administered in a combined longitudinal/cross-sectional design incorporating a number of methodological controls. The tasks spanned the entire sensorimotor period and included single versus sequential displacements combined with visible or invisible hidings. 36 infants from 5 to 32 months of age at initial testing were drawn equally from day-care and home settings. All infants received the 6 tasks during each of 3 testing sessions over a 6-month period. Clear evidence was obtained for task ordinality as proposed by Piaget, with ordinality coefficients ranging from .71 to .82 for the 3 testing sessions. Performance changes across the 3 sessions were also ordinal in 80% of the cases. Expected age, task, and session effects and accompanying interactions were also obtained.

Infants' sensitivity to correlations or co-occurrences among attributes may play a role in abilities ranging from pattern or object recognition to category formation. The present set of experiments investigated 4-, 7-, and 10-month-old infants' ability to perceive and base novelty responses on correlations among perceptual attributes in a category-like context (i.e., with the correlation embedded in a set of discriminable stimuli). In a habituation-dishabituation paradigm, 10-month-old infants clearly responded on the basis of the correlation among attributes. In contrast, 4- and 7-month-old infants responded primarily on the basis of specific featural information, but did not respond reliably to the correlation. It is suggested that the sensitivity to correlated attributes demonstrated by 10-month-old infants may have implications for the processes underlying the infants' categorization abilities.