others. It is not familiar to the infants and they have no expectation about it. Most infants fail to show distress despite the fact that an adult is not permitting them to move their arms as they would like. The explanation for this finding may be that the infants are too young to be frustrated in such a situation. Stenberg, Campos, and Emde ( 1983) observed that anger to arm restraint did not emerge until 4 to 6 months of age. It has been hypothesized that anger is not felt until an infant has the cognitive capacity to understand that some instrumental activity might accomplish a goal ( Darwin, 1872/ 1965; Lewis, 1991). Such an understanding of means-ends relationships does not generally emerge until at least 4 months of age ( Piaget, 1952). We see it during the contingency procedure because the infants can learn that their actions accomplish a goal. Infants who fall to learn the contingency do not show frustration when the contingency is no longer in effect. Thus, we suspect that our subjects did not have the capacity to be frustrated by their inability to move their arms for 30 seconds, reducing the amount of negative affect expressed.
Sound, prospective investigations of the impact of prenatal cocaine exposure on emotional functioning of the children are only in the early stages. The evidence to date, suggesting particular difficulties in the ability to recover emotional control following perturbations, indicates that this may be a critical area of examination. The capacity to recover one's equilibrium and move on to new situations is fundamental to the development of satisfying and nurturant social relationships, as well as to the capacity to adapt and to learn from objects, situations, and the people in one's environment. Further research must confirm and refine our understanding of the phenomenon and its etiology and approaches to modifying detrimental consequences.
Preparation of this chapter was supported by grant #DA07109 to Michael Lewis from the National Institute on Drug Abuse.
Alessandri S. M., Sullivan M. W., Bendersky M., & Lewis M. ( 1995). "Temperament in cocaine-exposed infants". In M. Lewis & M. Bendersky (Eds.), Mothers, babies, and cocaine: The role of toxins in development (pp. 273-285). Hillsdale, NJ: Lawrence Erlbaurn Associates.
Alessandri S. M., Sullivan M. W., Imaizumi S., & Lewis M. ( 1993). "Learning and emotional responsivity in cocaine-exposed infants". Developmental Psychology, 29, 989-997.