Effects of Chlordiazepoxide and Cocaine on Concurrent Food and Avoidance‐of‐timeout Schedules

Abstract

Five rats were trained on a concurrent schedule in which responses on one lever produced a food pellet on a random-interval 30-s schedule during 10 s of food availability associated with distinctive exteroceptive stimuli. Responses on another lever postponed for 20 s the presentation of a 50-s timeout, during which all stimuli were extinguished and the schedule contingencies on the food lever were suspended. The response rates maintained by the random-interval schedule exceeded those maintained by the avoidance contingency, but both provided a stable baseline to assess the behavioral effects of different drugs. Low doses of cocaine hydrochloride (1 and 3 mg/kg) did not affect food-reinforced responding or avoidance response rates. Intermediate doses (5.6, 10, and 13 mg/kg) produced a dose-dependent decrease in food-maintained and avoidance response rates, and both types of responding were virtually eliminated after administration of the highest doses (17 and 30 mg/kg) of cocaine. Low doses of chlordiazepoxide (1 and 3 mg/kg) increased food-maintained and avoidance response rates, and both rates decreased systematically after 10 and 30 mg/kg of this drug. The effects of cocaine and chlordiazepoxide on response rates maintained by avoidance of timeout from food presentation were unlike those reported when subjects responded to avoid shock presentation. The results of this experiment thus provide evidence to suggest that the effects of drug administration on avoidance behavior may be a function of the nature of the consequent event to be avoided.

Timeout Postponement Without Increased Reinforcement Frequency

“…Consistent with prior findings, the present results showed that responding can be maintained by postponing timeouts from a schedule of food delivery (D'Andrea, 1971;Ferster, 1958;Galbicka & Branch, 1983;Thomas, 1964Thomas, , 1965aThomas, , 1965bvan Haaren & Zarcone, 1994). In past studies, the effects of timeoutpostponement contingencies have been confounded with increases in the frequency of food reinforcement-an inevitable result of increased access to the reinforcement schedule available during time-in periods.…”

“…One way to determine whether an event is aversive is to examine whether its termination or postponement will support responding. Indeed, some of the clearest evidence favoring a view of timeouts as aversive emerges from studies of timeout avoidance, in which responding is maintained by the postponement or cancellation of timeout from a schedule of positive reinforcement (D'Andrea, 1971;Ferster, 1958;Galbicka & Branch, 1983;Hackenberg, 1992;Morse & Herrnstein, 1956;Thomas, 1964Thomas, , 1965aThomas, , 1965bvan Haaren & Zarcone, 1994;Zimmerman, 1963).…”

The aversiveness of timeout from response‐dependent and response‐independent food deliveries as a function of delivery rate

“…In basic research on aversive control, shock is a commonly used stimulus and it often serves as a reference stimulus when assessing the aversive function of other stimuli. Much research supports the notion that timeout functions in a comparable manner as shock when studied under similar experimental arrangements (DeFulio & Hackenberg, 2007; Kaufman & Baron, 1968; McMillan, 1967; Richardson & Baron, 2008; Thomas, 1965; but see exceptions in pharmacological studies reported by Branch et al, 1977, van Haaren & Anderson, 1998, and van Haaren & Zarcone, 1994).…”