The name is absent

The Brain and Behavior        61

studies on the performance of monkeys on a variety of tasks
led him to conclude that lesions in the frontal and prefrontal
areas had no effect on either retention or learning of simple
problem-box or pattern discrimination habits. Some impair-
ment was noted in the retention of a more complex combina-
tion-box habit, but this effect was also noted in parietal le-
sions so it could not be attributed to the frontal lobes them-
selves. In a later study Jacobsen (1935) found that bilateral
removal of the frontal lobes affected the performance of
monkeys on tests which required temporal sequences of
movements or delayed reactions. The interpretation of Jacob-
sen’s later work and of tire volume of research since that date
is still a subject for controversy (cf. Fulton, 1951, pp. 92-94).
It does seem to be justifiable, however, to offer the tentative
conclusion that, if the frontal lobes are significant for intel-
lectual processes in animals, they are necessary only for com-
plex behavior patterns.

The data on the effects of tissue removal from the human
frontal lobes are, of course, far less systematic and carefully
controlled than the data from animal studies. The evidence
available comes primarily from observations of the results of
surgical operations conducted for two different kinds of
reasons. (1) Tissue from the frontal lobes has been removed
because of the presence of tumors or traumatic injuries in
those areas. (2) Surgical intervention in the form of tissue re-
moval or the section of nerve fibers has been performed for
psychiatric purposes. A discussion of the rationale underlying
the use of surgical procedures for psychiatric purposes will
be deferred until the consideration of emotional processes in
the next section.

(1) Many of the clinical reports describing the effects of
frontal lobe operations performed to remove tumors are
poorly documented. Cases reporting gross defects of behavior

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