Abstract
Key-peck responding of pigeons was maintained under a fixed-interval 3-minute schedule of food delivery. Simultaneously, electric shock was delivered under a fixed-ratio schedule for responses occurring during alternate schedule components. Shock intensity and frequency were adjusted to produce either moderate or severe response suppression in the punishment components. Chlorpromazine, under both levels of punishment severity, further decreased most rates of punished responding, while generally increasing comparable rates of unpunished responding. Very low rates which occurred at the beginning of the punishment components were increased by drug, but to a lesser extent than comparable low rates of unpunished responding. The effects of morphine depended on shock severity. When punished responding was moderately suppressed (50-74%) with respect to unpunished responding, morphine increased comparable low rates in the two schedule components to the same extent. When punished responding was more severely suppressed, morphine further decreased very low rates of punished responding, but generally increased comparable rates of unpunished responding. The effects of both drugs on local rates within the intervals depended in an orderly way on control response rate.
Footnotes
- Received April 30, 1973.
- Accepted June 12, 1974.
- © 1974 by The Williams & Wilkins Company