PARAMETERS AFFECTING THE MAINTENANCE OF NEGATIVELY REINFORCED KEY PECKING¹

Abstract

Three negative reinforcement experiments employing a key-peck response are described. In Experiment I, pigeons shocked on the average of twice per minute (imposed condition) could produce, by pecking a key, an alternate condition with correlated stimuli. Delayed shocks were added, across sessions, to the alternate condition until pecking stopped. Two of three pigeons continued to peck despite a 100% increase in shock frequency. In Experiment II, pigeons were shocked in the imposed condition four times per minute. The postresponse delay to shock was held constant by delivering, in the alternate condition, the next shock, or the next two, three, or four shocks from the imposed-condition shock schedule. All three subjects continued to peck with no change in delay to the first two postresponse shocks but with a 75% reduction in shock frequency. In Experiment III, a response produced an immediate shock followed by a shock-free period. Three of four subjects continued to respond despite reduced delay to shock. Delay-to-shock or shock-frequency reduction was sufficient to maintain key pecking, but neither was necessary. The conditions that negatively reinforce the pigeon's key peck were similar to conditions that negatively reinforce the rat's bar press.

Delay or Rate of Food Delivery as a Determiner of Response Rate

“…Analogous results have been obtained with human children (Mischel & Metzner, 1962). In a complementary way, rats and pigeons have repeatedly emitted a response that avoided an otherwise immediate shock even when such responding has produced enough extra delayed shocks so that the total density of shocks in the situation actually increased (Gardner & Lewis, 1977;Hineline, 1977). These kinds of observations raise the possibility that rate of reinforcement might not participate directly in the differential reinforcement of responding.…”

Still No Evidence for Temporally Extended Shock‐frequency Reduction as a Reinforcer

“…As might be expected on the basis of his graduate training with W. N. Schoenfeld and F. S. Keller, Bersh (2001) does scrutinize the empirical data. He believes, for example, that certain results obtained by Gardner and Lewis (1977) provide support for Hineline's hypothesis that shock-frequency reduction over a temporally extended period is a sufficient condition for reinforcement. In their Experiment 2, Gardner and Lewis used a seemingly simple but highly confounded procedure.…”

“…For example, the shocks that continued into the alternative condition were added ad seriatim from the beginning of that condition. This means that the number of shocks delivered (categorized by Gardner & Lewis, 1977, under the heading of frequency) was highly correlated-confounded-with the length of time before the series terminated (categorized as delay). Also, these shocks were delivered in the presence of the alternative stimulus complex produced by the response.…”

The Molarity of Molecular Theory and the Molecularity of Molar Theory

“…Dinsmoor (2001) must assume that, despite no immediate change in aversiveness from preresponse to postavoidance response, the overall reduction in aversiveness reinforces the response. Gardner and Lewis (1977) found that a pigeon would acquire a response that resulted in a change from an imposed to an alternative condition, even though there was no change in delay to the first two shocks in the alternative condition, provided that there was a 75% reduction in shock frequency. If Dinsmoor is to account for these results without accepting shock-frequency reduction as an effective reinforcer, he must now assume that a subsequent delay to the next shock (in the imposed condition) after no postresponse change in aversiveness for one or two shocks is sufficient.…”

“…Hineline (1970) showed that shock-frequency reduction is not necessary, and that shock delay is sufficient. Gardner and Lewis (1977), however, have provided evidence that shock delay is not necessary, and that shock-frequency reduction is sufficient. The fact that the imposed and alternative conditions in their experiments have different correlated exteroceptive stimuli is considered a confounding effect by Dinsmoor.…”