| dc.description.abstract | Theories of resistance to extinction such as the generalized
decrement theory (GDT) have been largely based on research
involving isolated individuals. In the natural environment however,
extinction, like acquisition takes place in a social context. Very few
studies have addressed this issue and those that have either failed to
create a stable social environment or have not addressed the effect
of population density, an important aspect of sociality, on resistance
to extinction. To study this effect a group of eight rats was exposed to
two daily 30-minute VI-120 schedules of reinforcement in an eight
station operant conditioning arena. During each of four phases of the
experiment, the population was consistently exposed to the VI-120
reinforcement schedule at a given number of stations (n=l, 2, 4, 8).
Following each condition the rats were exposed to a session of
extinction in which bar pressing at a station no longer produced food.
To avoid the confounding effect of amount of reinforcement, since
only the number of work stations available and not the
reinforcement schedule changed, a second experiment was conducted
in which the VI schedule was varied to compensate for the amount
of reinforcement. According to the GDT the results should have
produced an increased resistance to extinction during trials when the
conditions of reinforcement were similar to conditions of extinction.
This similarity occurred when fewer bars were available for
reinforcement, which according to the GDT, should have created a
negative relationship between responses in extinction and the
number of stations presented. Exactly the opposite effect occurred;
that is, a decrease in resistance to extinction was observed when
fewer bars were presented to the rats. The data support an ecological
theory of social foraging called the skill pool effect, which predicts a
positive relationship between the number of responses in extinction
and the number of stations available. This suggests that social
learning and transmission mechanisms exist and should be
considered when evaluating the effectiveness of various learning and
foraging theories. | |
