The development of visual expectations in the first year.

The development of expectations was investigated by using the Visual Expectations Procedure. In Experiment 1, 128 infants aged 6-, 9-, and 12-months-old saw two 40-trial sequences of a videotaped mechanical toy appearing in various locations. The sequences represented an alternation pattern (i.e., ABAB) or a complex pivot pattern (i.e., ABCBABCB). In Experiment 2, 76 infants aged 4-, 8-, and 12-months-old saw either a left-right alternation or a top-bottom alternation. Reaction time improved and the percentage of anticipations increased between 6 and 9 months in Experiment 1 and between 4 and 8 months in Experiment 2 but not thereafter. Anticipations for the pivot sequence and for younger infants on both sequences were often incorrect (i.e., gaze shifts occurred before stimulus onset but were not directed toward the upcoming stimulus). We conclude that young infants have expectations that reflect some degree of general or procedural knowledge, but it is not clear that this behavior implies specific, articulated expectations about upcoming events.

Information processing and developmental assessments in 3-month-old infants exposed prenatally to cocaine.

OBJECTIVE: To determine the effect of prenatal cocaine exposure on 3-month infant information processing and developmental assessments. METHODS: One hundred and eight infants, 61 cocaine-exposed and 47 controls, participated at 3 months of age in an infant-control habituation and novelty responsiveness procedure and in a developmental assessment using the Bayley Scales of Infant Development both administered by experimenters blind to the drug exposure status of the infant. RESULTS: Compared to the non-drug-exposed group, infants exposed prenatally to cocaine were significantly more likely to fail to start the habituation procedure and, for those who did, significantly more likely to react with irritability early in the procedure. The majority of infants in both groups reached the habituation criterion, and among those who did there were no significant differences between cocaine and non-cocaine-exposed infants in habituation or in recovery to a novel stimulus. Infants who were cocaine-exposed showed comparatively depressed performance on the motor (Psychomotor Developmental Index) but not the mental (Mental Developmental Index (MDI)) scales of the Bayley. These results obtained for habituation and Bayley MDI controlling for both perinatal and sociodemographic factors. CONCLUSIONS: Differences in reactivity to novelty but not in information processing between cocaine-exposed and non-cocaine-exposed infants suggest that the effects of prenatal cocaine exposure may be on arousal and attention regulation rather than early cognitive processes.