In its most general form, the question to be discussed in this chapter concerns the relation between the development of a skill and the neural representation of that skill. If a certain pattern of neural organization characterizes normal children, what are the behavioral consequences of deviation from that pattern? Does deviant neural organization imply cognitive deficit? Does deficient cognitive development imply deviant neural organization? Specifically, this chapter concerns the relation between abnormal language development and the cerebral lateralization of language. Especially when defined broadly so as to include reading and writing, abnormal language development has traditionally been attributed to deviant cerebral lateralization (Orton, 1937). We shall examine the empirical and conceptual underpinnings of this attribution and arrive at some conclusions about the importance of cerebral lateralization in various forms of disordered language development.

A framework for evaluating the evidence

If the relation between disordered language development and the cerebral lateralization of language is to be understood, three categories of variables – pathological, behavioral, and developmental – must be considered.

Pathological variables

Much of our present knowledge about the basis in the brain for language development is derived from studies of children who have sustained lateralized brain damage. This source of information, though useful, is not without ambiguities. First, the outcome of such studies quite likely depends on how the children are identified.