Galizio, M. (1999).
Extinction of responding maintained by timeout from avoidance.
Journal of the Experimental Analysis of Behavior,
71, 1-11.
The resistance to extinction of lever pressing
maintained by timeout from avoidance was examined. Rats were trained under a
concurrent schedule in which responses on one lever postponed shock on a free-operant
avoidance (Sidman) schedule (response–shock interval = 30 s) and responses on
another lever produced 2 min of signaled timeout from avoidance on a variable-ratio 15
schedule. Following extended training (106 to 363 2-hr sessions), two experiments were
conducted. In Experiment 1 two different methods of extinction were compared. In one
session, all shocks were omitted, and there was some weakening of avoidance but little
change in timeout responding. In another session, responding on the timeout lever was
ineffective, and under these conditions timeout responding showed rapid extinction. The
within-session patterns produced by extinction manipulations were different than the
effects of drugs such as morphine, which also reduces timeout responding. In Experiment
2 shock was omitted for many consecutive sessions. Response rates on the avoidance
lever declined relatively rapidly, with noticeable reductions within 5 to 10 sessions.
Extinction of the timeout lever response was much slower than extinction of avoidance in
all 4 rats, and 2 rats continued responding at baseline levels for more than 20 extinction
sessions. These results show that lever pressing maintained by negative reinforcement
can be highly resistant to extinction. The persistence of responding on the timeout lever
after avoidance extinction is not readily explained by current theories.
Key words: avoidance, extinction, timeout, negative reinforcement, lever
press, rats