ABSTRACT
A phenotype is defined as “the manifest characteristics of an organism collectively, including anatomical and psychological traits, that result from both its heredity and its environment” (Neufeldt & Guralnik, 1988, p. 1013). The purpose of this chapter is to demonstrate the potential value of intervention research as a tool for understanding the nature of various behavioral phenotypes that are manifested at least in part by developmental language disorders. Because a phenotype by definition results from the interaction of heredity and environments, the first part of this chapter is devoted to the role of the environment in determining a phenotype and then the role of the phenotype in determining the environment. This discussion sets the stage for an examination of the central question; How can intervention research enhance our knowledge of specific phenotypes?
