76 The Rice Institute Pamphlet
with simple tasks and optimal conditions at about the same
rate. They show the same types of perceptual generalization,
the differentiation of figure from ground, the recognition of
similarities among objects. All show similar perception of
spatial relations. There are even suggestions of insight, or a
primitive grasp of logical relations, by animals as primitive
as the arthropods. The differences are quantitative rather
than qualitative.
“It looks as though these basic mechanisms of behavior
are somehow inherent in the structure of the nerve net, in
the primitive organization of nerve cells, and are largely in-
dependent of the gross structures which have been evolved
in phylogenetic history. Evolution of the nervous system
seems to have been largely a matter of meeting the demands
of the moment and of irreversibility of what has once been
started. The primitive mammal was almost certainly noc-
turnal, making little use of vision. The cerebral hemispheres
consequently developed as an outgrowth of the then domi-
nant olfactory brain. Had the creature been diurnal, its in-
tellectual development might have centered on the midbrain
with enlargement of the optic lobes, but with no great dif-
ference in the final intellectual achievement.
“My point is that, although the detailed tracing of the
structural changes of the brain in evolution is important for
understanding of the evolution of the brain, the gross struc-
tural changes may be almost completely irrelevant to the
problem of the evolution of behavioral or mental traits” (As-
sociation for Research in Nervous and Mental Disease, 1954,
p. 95).
The statements of Eccles and Lashley present a broader
perspective within which to view the research described in
the previous sections of this paper. Considering that psy-
chology is interested in data which would aid in the develop-