Fisio

E NVIRONMENTAL COMPLEXITY, CEREBRAL CHANGE,
AND BEHAVIOR '
MARK R . ROSENZWEIG
University of California, Berkeley

R

ELATING b rain processes to behavior in animals is the s ubject of this paper. Addressing an audience not f rom, my own special field reminds me of the animal psychologist who p resented a paper at a psychoanalytic meeting. At the end of the paper, one of the psychoanalysts grumbled, "We knew all this already."
"Yes," a colleague placated him, "but we d idn't know t hat it was t rue of rats I" In my own case, I hope t hat you will n either reject this research as irrelevant to your own n or, on the other hand, apply it u ncritically to work in h uman behavior and development. Therefore, a fter p resenting the main findings, I will w ant to discuss with you the possible significance of s uch work for the s tudy of human behavior.
The research has been done by a team in which
Edward L. Bennett, a biochemist, David Krech, a psychologist, and I have collaborated for a dozen years. M ore recently we have been joined by
Marian C. Diamond, a n euroanatomist. The overall scope of our p rogram concerns both h ereditary and e nvironmental factors t hat have been demonstrated to a ffect l earning ability. We have been attempting to determine whether they do so by affecting the a natomy and chemistry of the b rain.
Today I will c oncentrate on these questions: Can differential experience m odify the b rain in measurable anatomical and chemical terms? If so, can these cerebral changes be related to the e ffects of experience on learning ability?
The suggestion that t hinking might induce growth of the b rain is an old one, dating back at least to the late eighteenth century (Sommering,
1791). In the early nineteenth century, the phrenologist Spurzheim (1815) held it highly probable
1
A bbreviated version of an address given to t he Division o f D evelopmental Psychology a t A merican P sychological A ssociation, Chicago, S