FREE OPERANT AVOIDANCE AS A FUNCTION OF THE RESPONSE‐SHOCK = SHOCK‐SHOCK INTERVAL¹

Abstract

Two temporal parameters of free operant or Sidman avoidance behavior are the interval by which responses postpone shocks (Response-Shock interval) and the interval between shocks when no responses occur (Shock-Shock interval). Avoidance behavior was examined in three white rats under conditions where the Response-Shock and Shock-Shock intervals were always equal. With intervals from 10 to 60 sec response rates and shock rates were similar, decreasing, negatively accelerated functions of increasing Response-Shock = Shock-Shock interval. Over this range, response and shock rates were linearly related to the reciprocal of the ResponseShock = Shock-Shock interval. It was shown, however, that this relation cannot hold at extremely long intervals. Both the ratio of responses emitted to shocks received and the percentage of shocks possible which were avoided increased at long Response-Shock = Shock-Shock intervals. These findings may be related to the fact that long intervals provide optimal conditions for conditioning avoidance behavior in the rat.Free operant avoidance responding as a function of the Response-Shock (RS) and Shock-Shock (SS) intervals was first investigated by Sidman (1953 METHOD SubjectsThree adult male Sprague-Dawley rats weighing about 500 g were selected from a large group of rats which had been run on avoidance schedules for other purposes. They were selected on the basis of their low shock rates at RS = SS = 20. The history of two subjects (RA-53 and RA-62) consisted entirely of 6-hr sessions under RS = SS = 20 sec run on alternate days. The third subject

Warmup in Free‐operant Avoidance as a Function of the Response‐shock = Shock‐shock Interval

“…The differences can be readily attributed to the preselection of proficient avoiders in most studies; rats that in preliminary training have produced especially low shock rates would be expected to persist more than do the less-proficient animals on procedures with marginal reinforcing consequences for responding. Clark and Hull (1966) reported no irreversible effects resulting from exposure to short SS = RS intervals. In the present work, such irreversible effects were observed when such exposures occurred relatively early in training, as indicated by the necessity for deleting two animals given early exposure to short intervals, and by the inferior performance levels shown by the third such animal (Figure 1).…”

“…Using two rats, Herrnstein and Brady (1958) examined a set of smaller intervals, ranging from 5 to 20 sec, embedded in a multiple schedule that included appetitive behavior. Using three rats, Clark and Hull (1966) examined intervals ranging from 10 to 60 sec. All four experiments produced functions of approximately the same shape, resembling hyperbolic, or logarithmic relations between response rate and the SS = RS interval; their data gave approximately linear functions when rate was plotted against the reciprocal of the interval, at least over the ranges of intervals that were used.…”

“…Sidman (1953b) deleted the warmup periods partly because warmup appeared to be affected by the size of the SS and RS intervals, and this could have contaminated the measures of steady-state responding that were his main focus. Clark and Hull (1966) suggested that the duration of the warmup was relatively unaffected by the SS = RS intervals, but they discarded the relevant data without doing a separate analysis. Hoffman, Fleshler, and Chorny (1961), in examining warmup effects in signalled discrete-trial avoidance, suggested that animals with substantial warmup may often be labelled (even discarded) as poor avoiders, even though their late-session performances are quite proficient.…”

LEVER HOLDING UNDER FREE‐OPERANT AVOIDANCE1

“…The present study sought to discover if lever holding was correlated with the principal parameter of the freeoperant avoidance schedule, the responseshock interval. Studies by Sidman (1953), Verhave (1959), and Clark and Hull (1966) had shown that the rate of lever pressing, or the more refined measure of interresponse interval, as used by Wertheim (1965), may be functionally related to the value of R-S. If holding behavior is modulated by the R-S interval, such temporal response patterning could be explained by noting that changes in the rate of response observed under different R-S values are the outcome of the control of holding behavior by the punishment contingency.…”

The Effective Use of Secondary Data

“…In one figure he showed that the model provided excellent fits to the data from five individual animals from four different experiments (Clark & Hull, 1966;Hake, 1968;Sidman, 1953;Verhave, 1959). Although these experiments involved different species (rats, dogs, and monkeys) and different procedures, Gibbon demonstrated that simple quantitative functions based on scalar timing applied to results from all of them.…”