Pitts, R. C., & Malagodi, E. F. (1996).
Effects of reinforcement amount on attack induced under a fixed-interval schedule in pigeons.
Journal of the Experimental Analysis of Behavior,
65, 93-110.
Key pecking by pigeons was maintained on a chained fixed-interval
4-min (12-min for 1 subject) fixed-ratio 1 schedule of food
presentation. Attacks toward a restrained and protected
conspecific were recorded. In the first experiment, the amount of
food presented per interval was manipulated across phases by
varying the number of fixed ratios required in the terminal link
of the chain. Measures of attack for all pigeons during the
fixed-interval component increased monotonically as a function of
food amount. In the second experiment, two different food amounts
alternated within each experimental session under a multiple
schedule. For both pigeons in this experiment, measures of attack
were higher during the component that delivered the larger food
amount per interval. The differences in levels of attack induced
by the two food amounts in Experiment 2, however, were not as
great as in Experiment 1; apparently this was because attack
during the first interval of each component was controlled in
part (P-5626) or entirely (P-7848) by the reinforcement amount
delivered at the end of the previous component. Attack was also a
function of the location of the interfood interval within the
session. For both pigeons, attack tended to decrease throughout
the session. The results of both experiments suggest th at attack
is an increasing function of reinforcement amount under
fixed-interval schedules, but that this function may be
influenced by the manner in which reinforcement amount is
manipulated, by the duration of the interfood interval, and by
the location of the interfood interval within the experimental
session. In general, these results are compatible with theories
of induced attack and other schedule-induced behavior that
emphasize aversive aftereffects of reinforcement presentation.
Key words: schedule-induced attack, schedule-induced behavior,
reinforcement amount, fixed-interval schedule, key peck, pigeons