of illness (based on, e.g., the degree of cognitive
impairment present) as well as to help tailor treat-
ment strategies to patients’strengths and weaknesses
(Howieson & Lezak, 2010).
With these definitions and descriptions of the
roles of neuropsychologists in mind, we now turn
to a brief history of the field.
History of NeuropsychologyTheories of Brain Functioning. As in most areas
of psychology, the historical roots of neuropsychol-
ogy extend about as far back in time as we are
inclined to look. Some authors point to the
Edwin Smith Surgical Papyrus, a document
thought to date between 3000 and 1700 B.C.,
which discusses localization of function in the
brain (Walsh & Darby, 1999). Others suggest that
it all began when Pythagoras said that human rea-
soning occurs in the brain. Others are partial to the
second centuryA.D. when Galen, a Roman physi-
cian, argued that the mind was located in the brain,
not in the heart as Aristotle had claimed.
However, the most significant early base for
neuropsychology seems to have been laid in the
19th century (Zillmer et al., 2008). Researchers
then were beginning to understand that damage
to specific cortical areas was related to impaired
function of certain adaptive behaviors. The earliest
signs of this understanding came with Franz Gall
and his now discredited phrenology. Gall believed
that certain individual differences in intelligence
and personality (e.g., reading skills) could be mea-
sured by noting the bumps and indentations of the
skull. Thus, the size of a given area of the brain
determines the person’s corresponding psychologi-
cal capacity. This was the first popularization of the
notion of localization of function. Localization
achieved much greater credibility with Paul Broca’s
surgical work in 1861. Observations from two
autopsies of patients who had lost their powers of
expressive speech convinced Broca that he had
found the location of motor speech. Within the
next 30 to 40 years, many books presented maps
of the brain that located each major function
(Golden, 1984).
Others, such as Pierre Flourens, would surgi-
cally destroy certain areas of the brains of animals
and then note any consequent behavioral losses.
Such work led Flourens and later, in the early
20th century, Karl Lashley to argue for the concept
ofequipotentiality. That is, although there certainly is
localization of brain function, the cortex really
functions as a whole rather than as isolated units.
In particular, higher intellectual functioning is
mediated by the brain as a whole, and any brain
injury will impair these higher functions. Yet
there is the ability of one area of the cortex to
substitute for the damaged area.
Both the localization and equipotentiality theo-
ries presented some problems, however. Localiza-
tionalists could not explain why lesions in very
different parts of the brain produced the same deficit
or impairment, whereas those adhering to the equi-
potentiality theory could not account for the obser-
vation that some patients with very small lesions
manifested marked, specific behavioral deficits.
An alternative theory that integrates these two
perspectives is thefunctional model. First proposed by
the neurologist Jackson and later adapted by the
Soviet neuropsychologist Luria, the functional
model holds that areas of the brain interact with
each other to produce behavior. Behavior“is con-
ceived of as being the result of several functions or
systems of the brain areas, rather than the result of
unitary or discrete brain areas. A disruption at any
stage is sufficient to immobilize a given functional
system”(Golden et al., 1992). The importance of
this formulation is that it can account for many of
the clinical findings that are inconsistent with previ-
ous theories. According to the functional model, the
nature of the behavioral deficit will depend on which
functional system (e.g., arousal, perception, or plan-
ning behavior) has been affected as well as the locali-
zation of the damage within that functional system.
Finally, through a process called reorganization,
recovery from brain damage is sometimes possible.Neuropsychological Assessment. With regard
to specific psychological assessment instruments,
neurology was for a long time bewitched by notions
of mass action of brain functioning. These ideasNEUROPSYCHOLOGY 515