ABSTRACT
The study of individual differences has long been a mainstay of educational psychology. In his 1957 address to the American Psychological Association, Cronbach referred to correlational psychology as one of the two disciplines of scientific psychology, arguing for the importance of study of "variation between individuals, social groups, and species" (p. 671). In 1978 Tyler called for the study of "different patterns of mental organizatiun, different repertoires of competencies, and different strategies and styles" (p. 235). Exceptional conditions may be viewed as particular subsets of individual differences, or as representing the extremes of continua of individual variations. The qualitative-quantitative question is fundamental to the conceptualization and definition of exceptionality and influences decisions about assessment, identification, and instruction. It is a recurring issue in subsequent sections of this chapter.
