correctly. In addition to their laboratory studies, using a behavior rating scale they found children classified as exogenous to be more disinhibited, impulsive, erratic, and socially unaccepted (Strauss & Kephart,5 1939).
Werner and Strauss’s studies did not go without criticism. The focus of the criticism was on the procedures used to identify participants as exogenous versus endogenous mentally retarded. They diagnosed the child as having exogenous mental retardation if none of the immediate family members was retarded and if there was a history of prenatal, natal, or postnatal disease or damage to the brain. Additionally, a child could be diagnosed as exogenous mentally retarded purely on behavioral characteristics that previous research (e.g., Goldstein’s studies) had found associated with brain injury. For example, if the child was hyperactive and distractible in the classroom, then he or she was considered to have exogenous mental retardation. This reliance on behavioral symptoms for the diagnosis of exogenous mental retardation caused some to point out the possible circularity of forming their groups on the basis of symptoms that were very similar to the ones on which they were then attempting to differentiate the children (Sarason, 1949).
Criticisms of Werner and Strauss’s work were undoubtedly valid with respect to their attributing brain disease or injury as the cause of forced responsiveness to stimuli, hyperactivity, distractibility, and so forth. However, this does not deny the fact that Werner and Strauss had found consistent behavioral differences between the exogenous and endogenous groups, regardless of whether the differences were caused by brain injury or not:
It is important to point out here that up until this time mental retardation was perceived as a relatively homogenous state…. Consequently no differential or individual educational or psychological programming was initiated on their behalf. Dispelling the long-standing notion that there were no individual differences among the retarded, the work of Werner and Strauss, therefore, had revolutionary impact. (Hallahan & Kauffman, 1976, p. 6)
This impact was manifested in the form of differential educational programming for the exogenous group. Prompting the Wayne County researchers to look at individualizing instruction for the exogenous group was a survey they did of the first 500 admissions to Wayne County (Strauss & Kephart, 1939). They found that 4 or 5 years after admission to Wayne County, the IQs of the exogenous group declined 2.5 points whereas the IQs of the endogenous group increased 4.0 points. Furthermore, they investigated those children whose IQ scores could be traced back prior to institutionalization and found that the exogenous group showed a steady decline before and after institutionalization; but the endogenous group showed a decline in IQ until admittance, whereupon the trend was reversed and their IQs rose (Kephart & Strauss, 1940).
The Wayne County research team hypothesized that the endogenous group, in contrast to the exogenous group, was receiving an appropriate education. Noting the highly stimulating nature of the educational program at the school, they concluded that it was not a good fit for children who were highly distractible, impulsive, and hyperactive. Their first primary recommendation was to provide an environment in which inessential stimuli were attenuated and essential stimuli were accentuated (Werner & Strauss, 1940). This was followed by more elaboration on the teaching methods (Strauss, 1943), culminating with two classic volumes: Psychopathology and Education of the Brain-Injured Child (Strauss & Lehtinen, 1947) and Psychopathology and Education of the Brain-Injured Child: Progress in Theory and Clinic (Vol. 2; Strauss & Kephart, 1955). The first volume, in particular, described a number of educational recommendations for children with exogenous mental retardation. The focus of the recommendations was on providing a distraction-free environment for the students:
The class group is small—twelve children is the maximum number…. The classroom for these children is large enough to permit each child to be seated at a considerable distance from any other. There is only a minimum of pictures, murals, bulletin boards, and the usual stimulating visual materials of the average classroom. (Strauss & Lehtinen, 1947, p. 131)