D. Serruya et D. Eilam, STEREOTYPIES, COMPULSIONS, AND NORMAL BEHAVIOR IN THE CONTEXT OF MOTOR ROUTINES IN THE ROCK HYRAX (PROCAVIA-CAPENSIS), Psychobiology, 24(3), 1996, pp. 235-246
In the present study, we propose that the level of activity and organi
zation in time and in space are the common link between motor routines
in normal behavior, stereotypies, and compulsions. Specifically, an i
ncrease in activity, a shrinkage of the attended space, or an extensio
n of time results in repetitive performance. This hypothesis is based
on a discussion of stereotypies and compulsions in the context of moto
r routines in undisturbed behavior of the rock hyrax. Observations of
hyraxes in the wild and in captivity revealed that their behavior cons
titutes motor routines at several levels of organization: (1) Activity
is concentrated in a relatively limited region-a bush and an adjacent
rocky ramp; (2) in both morning and afternoon, the hyraxes ascend the
external branches of the bush, which they then leave in order to fora
ge; (3) moving from the bush to the ramp and vice versa occurs along c
ertain fixed routes; (4) while on the ramp, hyraxes tend to stop frequ
ently on only certain fixed stones; (5) each such ''preferred stone''
has a typical location and directions of approach and departure; and (
6) motor performance on the ''preferred'' stones typically involves cr
ouching or sitting in certain typical postures, and is preceded and fo
llowed by only a few (if any) lateral movements. We propose that these
recurrent behavioral patterns may constitute the normal foundation fr
om which a reminiscent rigid motor performance that characterizes ster
eotypy and compulsive behavior develops.