the continued expansion of role applications beyond traditional neurological, neuropsychiat-
ric, and rehabilitation settings into the forensic, educational, and vocational contexts.

The historical foundations of this specialty are already sufficient to warrant a detailed histori-
cal account of its evolution. Such an account is beyond the scope of this chapter, which is
designed to provide a general perspective by means of a review of major contributors in each
of the three aforementioned converging lines of knowledge and practice. Even such a brief
overview is insufficient to identify all major contributors so that the individuals identified
here by no means constitute an exhaustive list. Although incomplete, such identifications
may help to guide interested graduate students and practitioners in the field into the literature
and to aid in formulation of career objectives. Extensive introductions to the prescientific, as
well as the early scientific, literature of historical significance are available and should be
read by the serious student or practitioner ( Luria, 1966; Meyer, 1961). A review of modern
clinical neuropsychology in general historical perspective, but not a detailed history, is also
available ( Meier, 1992). This section summarizes the developments within each of the three
major developmental domains identified in the first paragraphs of this chapter.

Karl Lashley ( 1929) was an extremely influential individual during his time. Publication of
Brain Mechanisms and Intelligence resulted in the attribution of his intellectual leadership by
many individuals who themselves subsequently became major figures in this domain. The
doctrine of strict localization of function was widely held at that time; therefore, Lashley's
finding that the behavioral consequences of experimentally induced brain lesions in rats were
a direct function of the amount, rather than the location, of the tissue removed provided the
basis for an opposing doctrine that incorporated mass-action principles into a theory of brain
function. This work clearly forced an understanding of the nervous system as a functionally
dynamic and resilient system, as opposed to a static and discretely differentiated "switch-
board" conceptualization.

Although primarily an experimental psychologist, Lashley was known to rotate in clinical
settings, such as at St. Elizabeth's Hospital in Washington, DC, and at laboratories engaged
in the experimental analysis of higher cognitive functioning in primates, such as the Yerkes
Primate Laboratory. Many physiological and comparative psychologists worked directly with
Lashley, including Donald O. Hebb ( 1949), who subsequently engaged in interdisciplinary
clinical research with Wilder Penfield at McGill University, where they set in motion a major
series of research activities relating to the effects of removal of prefrontal or ante-
rior/mesiotemporal tissue on intractable focal seizure disorders and, by extension, on higher
cognitive and memory functioning. Hebb attempted to integrate the existing literature toward
achieving an empirically based foundation for the regional localization doctrine that sought
to formulate a rapprochement between the localizationistic and mass-action doctrines in the
analysis of the behavioral consequences of cerebral lesions and ablations. His characteriza-
tions of cell assemblies and their functional relationships were similar to such concepts as the
pluripotentiality of function and dynamic systems and subsystems as formulated by A. R. Luria
( 1966), the Russian psychologist and neurologist who is more widely acknowledged as
having attempted to synthesize elements of strict localization and mass-action doctrine to-
ward a general theory of higher cortical functioning. It was clear that the available empirical

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