Learning and emotional responsivity in cocaine-exposed infants.

This study examined both instrumental responses and facial expressions during learning and extinction in a group of cocaine-exposed infants ages 4 to 8 months. Of the 72 infants studied, half were exposed to cocaine in utero and halfserved as matched controls. The groups were matched on maternal demographic characteristics and maternal use of other substances. Findings indicated that (a) infants exposed to cocaine had a significant decrease in mean birth weight and birth length; (b) cocaine-exposed infants showed less overall arousal throughout the procedure; (c) cocaine-exposed infants expressed less interest and joy during learning and less anger and sadness during extinction; and (d) when control over the learning contingency was reinstated, cocaine-exposed infants did not show the expected increase in instrumental responding