Some Implications of Lateralization for Developmental Psychology
Sidney J. Segalowitz
Infants communicate with their mothers very soon after birth. Sometimes this communication involves subtle reciprocating body movements (e.g., of the tongue, eyes, mouth, fingers), and sometimes it involves exchanges of vocalizations. The intentionality of these interactions is evidenced by their regularity and by the negative reaction shown by the infant when the chain is broken ( Bretherton & Bates, 1979; Fafouti-Milenkovic & Uzgiris, 1979; Trevarthen, 1977). What can be said of the cerebral organization of such communicative skills? How does such a psychobiological basis relate to particular theoretical positions concerning the development of thought? In this section, we will focus on these related issues, the first concerning evidence for cerebral specialization of functions related to communication in infancy, the second focusing on the implication of this evidence for theories of cognitive development.
The most obvious relation between brain structures and the communicative function in humans is that the left hemisphere is responsible for language. It is wellestablished that in the vast majority of people, language is disrupted significantly