Marc N. Branch

Effects of acute and daily cocaine administration on performance under a delayed-matching-to-sample procedure

Food deprived pigeons were trained under a procedure in which trials began with the transillumination of one of three keys by red or green light. Pecking this key extinguished the light behind it and, after a variable delay (0.05, 0.5, 1.0, 2.0, or 4.0 sec), was followed by illumination of the two other keys, one by red light and one by green. Pecks on the key that was the same color as the previously illuminated key could produce access to food. High levels of accuracy were obtained at all delays. The acute and chronic effects of cocaine on performance generated by this procedure (delayed-matching-to-sample) were studied. Acutely, cocaine (0.56-10.0 mg/kg) produced dose-related decreases in accuracy and in rate of completing trials. Accuracy at the longest delay was more sensitive to cocaines effects. Daily administration of a comparatively large dose (5.6 mg/kg) resulted in tolerance to the rate-reducing and accuracy-reducing effects of large doses.

Where have all the behaviorists gone

Many of the world’s current problems are the result of behavior, and traditional appeals to mental determinants are again proving inadequate. The time for a behavioristic alternative appears ripe, yet many behaviorists seem to be becoming less behavioristic and more mentalistic. When confronted with the complexity of human behavior many are resorting to the intellectual comfort and safety of mentalism. A recent example of this tendency (Schwartz et al, 1978) is presented and discussed. Additionally, speculations regarding the origins of the resurgence of mentalism are presented, and it is proposed that arranging histories which provide for more rigorous and lasting control of verbal behavior about behavior may serve to improve the situation.

Malignant side effects of null-hypothesis significance testing:

Six decades-worth of published information has shown irrefutably that null-hypothesis significance tests (NHSTs) provide no information about the reliability of research outcomes. Nevertheless, they are still the core of editorial decision-making in Psychology. Two reasons appear to contribute to the continuing practice. One, survey information suggests that a majority of psychological researchers incorrectly believe that p values provide information about reliability of results. Two, a position sometimes taken is that using them to make decisions has been essentially benign. The mistaken belief has been pointed out many times, so it is briefly covered because of the apparent persistence of the misunderstanding. The idea that NHSTs have been benign is challenged by seven “side-effects” that continue to retard effective development of psychological science. The article concludes with both a few suggestions about possible alternatives and a challenge to psychological researchers to develop new methods that actually assess the reliability of research findings.

Tolerance to effects of cocaine on schedule-controlled behavior: Effects of fixed-interval schedule parameter☆

Tolerance to the effects of cocaine on key pecking by pigeons, maintained by differently valued fixed-interval schedules of food presentation, was studied. Key pecking was established on a multiple fixed-interval 5-sec fixed-interval 30-sec fixed-interval 120-sec schedule. Cocaine (1.0-10.0 mg/kg) was administered acutely and then chronically (i.e., before each session) in 5.6 mg/kg doses. Acute cocaine administration produced dose-related decreases in response rates under all three schedules. When cocaine was administered chronically, response rates either recovered fully, or increased to the extent that no reinforcers were missed during the sessions. The development of tolerance was not systematically related to the schedule value. Considered in relation to previous research, these results indicate that different control rates of reinforcement, within the schedules and parameters studied, do not contribute to tolerance to cocaines behavioral effects.

Statistical inference in behavior analysis: Some things significance testing does and does not do

Significance testing plays a prominent role in behavioral science, but its value is frequently overestimated. It does not estimate the reliability of a finding, it does not yield a probability that results are due to chance, nor does it usually answer an important question. In behavioral science it can limit the reasons for doing experiments, reduce scientific responsibility, and emphasize population parameters at the expense of behavior. It can, and usually does, lead to a poor approach to theory testing, and it can also, in behavior-analytic experiments, discount reliability of data. At best, statistical significance is an ancillary aspect of a set of data, and therefore should play a relatively minor role in advancing a science of behavior.

Acute and chronic effects of Δ9-Tetrahydrocannabinol on complex behavior of squirrel monkeys

Squirrel monkeys were, trained to press either two (phase one) or five (phase two) differently colored keys sequentially. Food presentation resulted if colors were pressed in a specific order, and high levels or accuracy were generated. Acutely, Δ9-tetrahydrocannabinol reduced accuracy and rate of responding in a dose-related fashion under both the two-key and fivekey conditions. Responding, however, was more sensitive to the drug under the five-key procedure. Accuracy of responding at the beginning of a sequence tended to be more sensitive to drug effects than responding near the end. Daily (chronic) administration resulted in the development of tolerance to both the rate-and accuracy-reducing effects of the drug, although tolerance developed more rapidly to the accuracy-reducing effects. Tolerance developed more slowly under the five-key procedure than under the two-key procedure. Details of tolerance development were related to aspects of acute effects, suggesting that some facets of tolerance development may be predictable from acute drug effects.

Schedule-dependent tolerance to behavioral effects of Δ9-tetrahydrocannabinol when reinforcement frequencies are matched ☆

Squirrel monkeys pressed a lever under a multiple interresponse-time greater than 28-sec, modified random-interval schedule which provided comparable frequencies and temporal distributions of food pellet presentation in the two components. Daily intramuscular administration of either 0.25 or 1.00 mg/kg delta 9-tetrahydrocannabinol resulted initially in suppression and/or disruption of responding and concomitant decreases in the frequency of food presentation in both components. Responding in both components next increased, resulting in recovery of baseline frequencies of pellet delivery during the random-interval component, but continued depression during the interresponse-time schedule. The drug-induced changes in responding under the interresponse-time schedule diminished with repeated injections, whereas response rates during the random-interval schedule sometimes remained elevated. Interresponse-time distributions under the interresponse-time schedule showed that with repeated administration of the drug only those characteristics which had the greatest effect on reinforcement frequency recovered to baseline levels. When drug injections were replaced by daily injections of the vehicle, responding was greatly disrupted only during the random-interval component. These findings are only partially consistent with other results which suggest aht tolerance development to the behavioral effects of delta 9-tetrahydrocannabinol is greatly enhanced if the drug initially produces reinforcement loss.

Persistence of tolerance to effects of cocaine on schedule-controlled behavior in pigeons.

Keypecking by seven pigeons, maintained by a fixed-ratio 30 schedule of food presentation, was decreased in rate by acute pre-session administration of cocaine. In Part 1 (four pigeons), tolerance to the rate-suppressing effects of cocaine developed during daily administration conditions. Tolerance persisted (1) when daily cocaine injections were replaced by conditions in which cocaine was administered every other day, then every fourth day, then every eighth day, then every 16th day, with all intervening sessions preceded by saline injections and (2) when daily cocaine administration was replaced abruptly by a condition in which cocaine injections were spaced 16 days apart, with all intervening sessions preceded by saline. In Part 2 (three pigeons), tolerance developed during intermittent administration conditions (e.g. cocaine injected every eighth day) for two subjects, and during daily administration for the third subject. As in Part 1, tolerance persisted when cocaine was administered only once even 16 days. These results are consistent with an interpretation of tolerance based upon operant compensatory reactions to drug-induced behavioral disruptions and suggest that a simple associationist model of tolerance to cocaine-induced response-rate suppression may be inadequate. The data also have practical implications regarding tolerance development during intermittent administration conditions similar to conventional acute dose-effect determination procedures.

Sensitization to cocaine in pigeons: interaction with an operant contingency.

A 2-part study with pigeons investigated the role of an explicit operant contingency in determining how cocaine interacts with locomotor activity. In Part 1, pigeons pecked on a fixed-ratio-20 schedule of food presentation. In Part 2, different pigeons were studied without opportunity to peck for food. After determination of cocaines initial effects, pigeons were exposed to daily administrations of a locomotion-increasing dose of cocaine. Locomotor sensitization was evident in the pigeons of Part 2, and tolerance developed to cocaines effects on key pecking in the pigeons of Part 1. Locomotor sensitization was generally not evident in the pigeons of Part 1. These results suggest that explicitly conditioned operant behavior may compete with behavior sensitized by prolonged exposure to cocaine.

Behavioral factors in drug tolerance

Publisher Summary This chapter describes the behavioral factors in drug tolerance. Following repeated exposure, the effects of a drug can either be unchanged, lessened, or increased. When a drugs effects are diminished following exposure to it, the change is called tolerance, when they are enhanced the change is called sensitization. One simple way to define a change in a drugs effects is in terms of potency. Potency refers to the amount of drug needed to produce a particular effect. Using this simple approach, tolerance can be said to have occurred when it takes more drug to produce a specific effect. Conversely, when it takes fewer drugs to produce a given effect sensitization is invoked. The chapter also describes laboratory investigations of the effects of repeated exposure to drugs. It focuses on the behavioral effects of drugs and operant behavior. The chapter describes the roles played by contingent relations among drug administration, behavior, and the consequences that maintain behavior as the key factors in determining the outcomes of repeated drug administration.