Peter H. Glow

Effects of dexamphetamine, amylobarbitone sodium and their mixture on sensory contingent bar pressing behaviour in the rat

The effects of the chronic administration of dexamphetamine, (one of five doses from 0.1 to 1.6 mg/kg), amylobarbitone sodium, (one of five doses from 1.0 to 16.0 mg/kg) and a mixture of the two (all of five doses, all at a constant ratio of 1.10 by weight) on sensory contingent bar pressing (SCBP) were investigated. 144 female Wistar rats bar pressed for 3 sec light and sound change as the only reward for their behaviour. The dose-response relationship under both dexamphetamine and the mixture took the form of an inverted U shaped function. Responding was not affected by amylobarbitone. The optimum doses of dexamphetamine and the mixture produced the same significant increase in SCBP, an effect which emerged over the initial trails. The results suggest that response feedback from the environment is magnified and thereby increases the reward value of SCBP. SCBP seems to have a number of advantages for the study of psychoactive drugs and intrinsic motivation.

Response-contingent sensory change in a causally structured environment

Sensory-contingent barpressing was studied in a causally structured environment. It was found that the reinforcing effect of sensory change was enhanced when it signaled the opportunity to produce a further, different sensory change. Prior experience of different kinds of lack of control was found to influence the amount of barpressing under full control. In general, lack of control which involved ineffective responding produced decreased responding under full control, whereas lack of control which involved lack of opportunity to respond tended to increase responding under full control. The results were interpreted in accordance with three hypotheses: learned ineffectiveness, frustration, and preference shift.

Some acquisition and performance characteristics of response contingent sensory reinforcement in the rat

Abstract The lever pressing behaviour of two groups of hooded rats was studied, the first group received response contingent Light ON and the second received response contingent Light OFF. On a variety of measures, Light OFF stimulation was found to be more reinforcing than an equal period of Light ON. The Light ON and Light OFF groups could be distinguished with respect to the shape of their acquisition and performance curves. Sensory reinforcement of bar pressing was also investigated with a requirement of two responses for stimulus change, and when the onset or offset of light was controlled by the animal. An adequate explanation for the performance phase of sensory contingent bar pressing is that sensory change as such is reinforcing, provided that the stimulation parameters are appropriate.

Response contingent auditory reinforcement in the rat

The acquisition and performance levels of responding for auditory intensity changes in rats are presented. A sound decrease was found to be more reinforcing than an equivalent sound increase. A preference experiment ruled out the possibility that the differences found could be accounted for by an aversion for the higher sound intensity. Several parallels between the reinforcing properties of sound and light intensity changes are drawn. The results are interpreted as showing that a change per se in the auditory modality can be reinforcing.

Chronic reduction of cholinesterase and the extinction of an operant response

SummaryThe extinction of an operant response was studied in rats in which cholinesterase activity was chronically inhibited to 30% of normal values. Resistance to extinction was related to the duration that cholinesterase had been reduced. The total number of extinction responses was less than for controls after 0 and 9 days and more after 18 and 36 days of reduced cholinesterase.

Sensory-contingent barpressing for familiar and novel change under a dexamphetamine-amylobarbitone mixture

In three experiments the effects of administration of Drinamyl (a mixture of dexamphetamine and amylobarbitone in the ratio of 1:6.5 by weight) on responding for novel and familiar sensory change was examined. In the first experiment, an acute administration of Drinamyl enhanced sensory-contingent barpressing (SCBP) with no differential effect for novel vs familiar change. In the second experiment acute Drinamyl also enhanced SCBP, with a larger effect for novel change. In a third experiment the effect of chronic Drinamyl administration was studied. Responding was substantially increased, with responding for sound change showing a greater effect than for light change. Responding for sound change also increased markedly over trials. When the sensory reinforcers were deleted, responding declined. The results were interpreted in terms of an increase in the reward value of SCBP under the drug.

Drug enhanced sensory contingent bar pressing: comparing the effect of contingent and noncontingent sensory change.

Bar pressing for sensory change as the reinforcer is markedly enhanced by the administration of dexamphetamine or a mixture of dexamphetamine and amylobarbitone. The present experiment was concerned with possible mechanisms underlying the enhanced responding and investigated the effects of response-contingent (feedback) versus noncontingent sensory change on responding under the two drugs separately, their mixture, or placebo. In Phase I animals were reinforced with a light and sound change combined and given drug injections prior to each of eighteen 20 min trials. In Phase II, the four drug treatments were each divided into seven matched groups operating under different reinforcement conditions to assess (a) the effect of deleting either the sound or light component of the reinforcer and (b) the effect of giving the deleted change or changes on a noncontingent basis. Responding declined when either the sound or both the sound and light were deleted but was not affected by the presence of noncontingent sensory change. It was concluded that dexamphetamine and the mixture operate directly to enhance the reward value of feedback sensory change.

SOUND AND LIGHT PREFERENCE BEHAVIOUR IN NAIVE ADULT RATS

Abstract An alternation procedure, over 18 × 20 min. trials, was used to investigate the preference for one of two levels of ambient light intensity (light or darkness) or one of two levels of sound intensity, in naive adult rats. A response (bar press) produced a change in the ambient stimulus intensity from one level to the other. The number of responses for change and the time spent in the two stimulus intensity levels were recorded. No preference for either sound level emerged. A slight preference for light as opposed to darkness developed over trials. More responses were made for a light change than for a sound change. These results from naive animals are in agreement with earlier work on sound and light preferences examined in rats which had had extensive previous experience with responding for sensory change. The results support the contention that where behaviour is reinforced by response contingent sensory change, preference for a particular intensity of stimulation is not a significant factor in...

A period of time-out from flickering light as a sensory reinforcer

A period of cessation of flickering light (darkness and light for 0.5 sec. intervals) was made contingent on the bar pressing of hooded rats. The cessation period consisted of either continuous darkness or continuous light, for 1.5, 3.0 or 6.0 sec. Cessation of flicker was reinforcing only if the “time-out” period was continuous darkness. The notion that a discrepancy from any kind of stimulus adaptation level, with equal discrepancies being equally rewarding, is not entirely supported by the results. The direction of change is important in determining the effectiveness of a sensory change as a reinforcer. The results of a separate phase of the experiment demonstrated that this finding can not be accounted for by a greater preference for darkness versus flickering light than for continuous light versus flickering light. No preferences were exhibited.

Active versus Passive Control in Sensory Contingent Bar Pressing in Rats

Previous studies have shown that sensory reinforcement in a causally structured environment can sustain relatively high levels of responding. In order to test the hypothesis that control of the environment has motivating/reinforcing properties, an experiment was conducted in which rats (N = 112) could exert control passively though withholding a response, as well as actively, and could maintain the status quo, as well as produce a change. It was found that rats did exert control passively, as well as activity, and did withhold responding to preserve the status quo, as well as to produce a sensory change.