Alan Russell

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 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.

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.

The effects of magnitude and duration of change on the light‐contingent bar pressing of hooded rats

Abstract A prediction from a Stimulus-Change theory of light-contingent bar pressing (LCBP) is that within a range, larger magnitudes of change will be more reinforcing. This was tested with hooded rats for light intensity Increments and Decrements. In addition to magnitudes, the effect of the duration of change was also investigated. The response results for light Increments showed an initial inverted U effect for magnitudes, followed by a general positive relationship over the remaining trials. Only the largest light Decrement was reinforcing. It was argued that these results support a Stimulus-Change explanation of LCBP. The magnitude effect was contrasted with comparable data from albino rats. While shorter durations of light Increment were the most reinforcing, there was a suggestion that a longer duration of light Decrement was the most effective. Therefore, the relative reinforcing value of Increments and Decrements differed according to the duration of change.

Sensory reinforcement using paired stimuli from different modalities

Abstract The effects of the concurrent presentation of two sensory changes contingent upon a bar pressing response of rats were investigated. Initially, a performance asymptote was established with one sensory reinforcer after which a second sensory reinforcer was added. When an asymptotic performance level was reached with the paired sensory reinforcers, one was deleted. The addition of a second sensory change initially produced a marked increase in the response rate. This rate declined to a new and only marginally elevated asymptote in subsequent trials. It was suggested that an early summation in the reinforcing effectiveness of two combined sensory changes gives way to a later interaction in their reinforcing effectiveness.

Successive discrimination in the rat using sensory change as the reward

An experiment was conducted with rats as Ss to determine if sensory reinforcement could support a successive discrimination. The animals were reinforced with either light Offset or sound Offset over a number of trials. In consecutive 2.5 min periods of each 20 min trial, bar pressing was reinforced with sensory change and then not reinforced. In some treatments distinctive environmental cues were associated with reinforcement and non-reinforcement periods. Control groups were reinforced throughout the whole trial. Reversal of cues associated with reinforcement and nonreinforcement periods occured in later phases of the experiment. The results showed that the sensory rewards supported a successive discrimination.

Manurcript recetved 31 Auguat, 1971)

This experiment was designed to determine if a sensory reinforcer would impart secondary reinforcing properties to another stimulus. A decrease in sound intensity (Sound OFF) was the sensory reinforcer. Sound OFF was paired with a light stimulus over several trials. By extinction testing it was found that this pairing procedure had resulted in the acquisition of secondary reinforcement. This shows that sensory reinforcers do not differ from the conventional rewards based on organic needs with respect to the ability to impart reinforcing properties to other stimuli. It is argued that these results are not in agreement with the information hypothesis of secondary reinforcement. The data were accounted for mainly in terms of Kellehers conditioning model.