|
Punishment of schedule-induced
drinking in rats by lick-dependent lever withdrawal
Ricardo Pellón
and Ángeles Pérez-Padilla
Universidad Nacional
de Educación a Distancia, Spain
Six food-deprived rats were exposed to a fixed-interval 30-s
food reinforcement schedule and developed stable patterns of
operant lever pressing and schedule-induced drinking (Stage
A). Animals were matched in three pairs according to their final
levels of response rates. Each lick made by any master rat then
initiated a resetting 10-s period of lever withdrawal without
stopping the fixed-interval timer (Stage B). This led to reductions
in licks per minute in all animals, without accompanying decreases
in the rate of lever pressing or in reinforcement rate. Drinking
and pressing in yoked-control rats, which received food at the
same times as those exposed to the lick-dependent lever withdrawal
contingency (masters), were not generally altered during Stage
B. A rat showed an increase in licks per minute. Initial conditions
were reinstated during the last phase of the experiment (Stage
A); licking produced no longer any programmed consequence. Schedule-induced
drinking of master rats recovered, and no significant changes
were observed in the behaviour of control rats or in lever pressing
by master rats. These results amplify our knowledge about the
procedures capable of punishing schedule-induced polydipsia,
and support the view that simply removing the opportunity to
press an operant lever on well-trained animals is sufficient
to punish adjunctive drinking.
Keywords: schedule-induced drinking,
punishment, lever withdrawal, fixed interval, rats |