Abstract
One group of pigeons responded under a five-minute fixed-interval schedule of food presentation, with every 30th response producing an electric shock (punishment group). Another group responded under the same schedule of food presentation, but without electric shock (nonpunishment group). All birds showed the usual fixed-interval pattern of responding. Although the average rate of responding was much lower in the punishment group, the lowest rates (at the start of the interval) for the nonpunishment group were comparable to the highest rates (at the end of the interval) for the punishment group. Chiordiazepoxide, diazepam and nitrazepam markedly increased average rates of responding in the punishment group, whereas they only slightly increased average rates in the nonpunishment group. In birds of both groups, the proportional increases in rates of responding in tenths of the fixed interval were inversely related to control rates of responding. Where rates of responding were comparable for the two groups, increases produced by the benzodiazepines were comparable. In contrast, imipramine increased rates of responding in the nonpunishment group, whereas it decreased rates in the punishment group. The results suggest that the benzodiazepines tend to increase relatively low rates of responding regardless of how these rates are established.
Footnotes
- Received June 13, 1969.
- Accepted December 15, 1969.
- © 1970, by The Williams & Wilkins Co.
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