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At least 1,621 records · Page 90Linked to original sources
PubMed1962

Spaced responding in multiple DRL schedules.

Rats were able to adjust to two different temporal requirements within several multiple DRL schedules of reinforcement, and a slight induction between pairs of components was found. Initial administration of dl-amphetamine differentially disrupted spaced responding in the components of a multiple DRL 36 DRL 18 schedule, but did not eliminate discrimination between the components. After maximum drug effects, the continued administration of dl-amphetamine was accompanied by a progressive recovery of the behavior towards the characteristics of saline control.

Amphetamine↗
PubMed1963

Effects of chlorpromazine and d-amphetamine on escape and avoidance behavior under a temporally defined schedule of negative reinforcement.

Chlorpromazine hydrochloride and d-amphetamine sulphate were administered to two rats responding on a baseline temporally defined schedule of negative reinforcement which produced both "escape-like" and "avoidance-like" behavior. The effects of these drugs appeared similar to those expected on the more customary sort of non-cued avoidance schedule.

Amphetamine↗
PubMed2003

Preserved sensitivity to outcome value after lesions of the basolateral amygdala.

Recent work (Blundell et al., 2001; Balleine et al., 2003) has suggested that the basolateral region of the amygdala (BLA) is important in the representation of the sensory and incentive aspects of motivationally significant events. In common with other theories of function of the BLA, this predicts that lesions of the BLA will interfere with reinforcer devaluation after appetitive Pavlovian or instrumental conditioning. However, this hypothesis also predicts that BLA lesions will be without effect on postconditioning changes in reinforcer value if initial learning is only about the sensory aspects of otherwise neutral events. This interpretation is supported by evidence for significant detrimental effects of BLA lesions on reinforcer devaluation in a Pavlovian autoshaping procedure, but no effect of postconditioning devaluation using a sensory preconditioning procedure. These results demonstrate that animals with BLA lesions can remain sensitive to post-training changes in the motivational value of outcomes.

Amygdala↗
PubMed1982

Changeover delay effects on topographically tagged discriminative behavior.

In a multiple variable-interval extinction schedule, pigeons' responses on an operant key were differentially reinforced in the presence of discriminative stimuli located on a signal key. Changeover delays of zero, one, two, or four seconds specified the time following a signal-key response within which an operant-key response was not reinforced. Systematic reduction of signal-key response rates with increasing changeover-delay duration indicated that signal-key responding was largely maintained by reinforcement of adventitious signal-key/operant-key response chains.

Animals↗
PubMed2000

Choice in a variable environment: every reinforcer counts.

Six pigeons were trained in sessions composed of seven components, each arranged with a different concurrent-schedule reinforcer ratio. These components occurred in an irregular order with equal frequency, separated by 10-s blackouts. No signals differentiated the different reinforcer ratios. Conditions lasted 50 sessions, and data were collected from the last 35 sessions. In Part 1, the arranged overall reinforcer rate was 2.22 reinforcers per minute. Over conditions, number of reinforcers per component was varied from 4 to 12. In Part 2, the overall reinforcer rate was six per minute, with both 4 and 12 reinforcers per component. Within components, log response-allocation ratios adjusted rapidly as more reinforcers were delivered in the component, and the slope of the choice relation (sensitivity) leveled off at moderately high levels after only about eight reinforcers. When the carryover from previous components was taken into account, the number of reinforcers in the components appeared to have no systematic effect on the speed at which behavior changed after a component started. Consequently, sensitivity values at each reinforcer delivery were superimposable. However, adjustment to changing reinforcer ratios was faster, and reached greater sensitivity values, when overall reinforcer rate was higher. Within a component, each successive reinforcer from the same alternative ("confirming") had a smaller effect than the one before, but single reinforcers from the other alternative ("disconfirming") always had a large effect. Choice in the prior component carried over into the next component, and its effects could be discerned even after five or six reinforcement and nonreinforcement is suggested.

Animals↗
PubMed1969

Learning sets in an invertebrate.

Eight isopods, Porcellio scaber, were trained with water reinforcement to turn in a T-maze to criterion of correct responses. They were then tested through nine reversals of the turning response. An analysis of variance indicated that mean errors to criterion declined significantly over reversals (F = 4.78, d.f. = 9/63, P < .001).

Analysis of Variance↗
PubMedDate not supplied

[Effect of the enkephalin derivative DAGO on neuronal behavior and activity in the neocortex and hippocampus of rabbits during the acquisition of conditioned defense and inhibitory reflexes].

After subcutaneous injection of 25 mkg/kg morphine-like opiate--DAGO a decrease was observed of probabilities of rabbits movements at light flashes--defensive reflex signal. The level of the background neuronal impulse activity became gradually lower in the sensorimotor cortex and the hippocampus and did not change in the visual cortex. Decrease and restoration of responses to the reinforcing stimulus (electrocutaneous limb stimulation) in all studied cortical zones proceeded in one direction while there were significant differences in dynamics of responses to inhibitory and reinforced light flashes depending on the studied cortical zone and biological significance of the stimulus. Appearance is discussed of particular characteristics of neurones systemic organization during learning at change of reinforcement properties under the influence of the studied substance, as well as similarity of some features of mechanisms of internal inhibition elaboration in a defensive situation and of properties of positive reinforcement.

Animals↗
PubMed1986

The effects of (+)-amphetamine and apomorphine on responding for a conditioned reinforcer.

Two psychomotor stimulants, (+)-amphetamine and apomorphine, were examined for effects on associative learning and responding for a conditioned reinforcer. The experimental phases included: preexposure to an operant test chamber with two levers, each of which produced a neutral stimulus when pressed; pairings of one stimulus with food; and a subsequent test of lever pressing for the two stimuli. Groups of food deprived rats (n = 8-12) were given IP injections of one stimulant prior to each pairing or testing session. Given during pairings, (+)-amphetamine produced a dose-related attenuation of responding for the conditioned stimulus in the test; doses of 0.5, 1.0 and 2.0, but not 0.25 or 4.0 mg/kg, given during the test enhanced responding, as did 0.5 mg/kg given in both phases. Apomorphine did not significantly alter responding during testing when administered in either the pairing (0 0.75 mg/kg) or test (0.5 1.0 mg/kg) phase. The results suggest that the modulation of conditioned reinforcement by psychomotor stimulants may occur through a presynaptic influence. Furthermore, the results with (+)-amphetamine suggest that this drug differentially affects the learning of an association between a conditioned and unconditioned stimulus versus the acquisition of responding for that conditioned stimulus.

Animals↗
PubMedDate not supplied

Over-reinforcement protects against memory deficits induced by muscarinic blockade of the striatum.

It has been shown that blockade of muscarinic receptors of the anterior striatum (AS) induces significant impairments in the retrieval of stored information of a passive avoidance task, trained with conventional parameters of footshock, and that the same blockade is ineffective in altering short-term memory of this task. The results of the present experimental series showed that in conditions of over-reinforcement, microinjections of scopolamine into the AS shortly after training or before retention testing of passive avoidance, do not produce memory deficits when retention is assessed 30 min, 24 h or 48 h after training. It is suggested that after an enhanced learning experience (over-reinforcement) striatal cholinergic activity is not involved in short- and long-term memory functions.

Animals↗
PubMed1999

The dynamics of operant conditioning.

Existing models of operant learning are relatively insensitive to historical properties of behavior and applicable to only limited data sets. This article proposes a minimal set of principles based on short-term and long-term memory mechanisms that can explain the major static and dynamic properties of operant behavior in both single-choice and multiresponse situations. The critical features of the theory are as follows: (a) The key property of conditioning is assessment of the degree of association between responses and reinforcement and between stimuli and reinforcement; (b) the contingent reinforcement is represented by learning expectancy, which is the combined prediction of response-reinforcement and stimulus-reinforcement associations; (c) the operant response is controlled by the interplay between facilitatory and suppressive variables that integrate differences between expected (long-term) and experienced (short-term) events; and (d) very-long-term effects are encoded by a consolidated memory that is sensitive to the entire reinforcement history. The model predicts the major qualitative features of operant phenomena and then suggests an experimental test of theoretical predictions about the joint effects of reinforcement probability and amount of training on operant choice. We hypothesize that the set of elementary principles that we propose may help resolve the long-standing debate about the fundamental variables controlling operant conditioning.

Animals↗
PubMed1998

Effect of reinforcement on facial responsivity and persistence in children with attention-deficit hyperactivity disorder.

Children with Attention Deficit-Hyperactivity Disorder (ADHD) may learn poorly under conditions of inconsistent (partial) reinforcement because they are easily frustrated and fail to develop persistence. To test this hypothesis, a nonsense word spelling task was used with 22 ADHD and 20 control children to investigate the effects of partial and continuous reinforcement on facial responsivity (frustration measure), words spelled correctly (learning performance measure), and persistence ratings. Partially reinforced ADHD children manifested higher levels of frustration in both acquisition and extinction than any other group and gave significantly lower persistence ratings across acquisition than partially reinforced control children. ADHD children spelled fewer words correctly than controls, regardless of reinforcement schedule. These findings suggest that partial reinforcement training develops persistence in normal but not ADHD children. The findings have theoretical implications for the etiology of ADHD as well as practical implications for designing behavior modification programs to treat ADHD.

Attention↗
PubMed1971

Color alternation learning in the pigeon under fixed-ratio schedules of reinforcement.

Pigeons were trained on a non-spatial delayed alternation task in which the correct stimulus was that color not responded to on the preceding trial. Subjects required to emit either 15 or 30 pecks to the correct stimulus within a trial learned the task, those required to emit only one or five pecks did not. Also, alternation was learned more easily after an incorrect than after a correct trial. Later experiments showed that a minimum fixed-ratio value was required for successful color alternation to occur, even though no fixed-ratio requirement was necessary when a position cue was available. The mechanism of the fixed-ratio effects derived from the pigeons' tendency to repeat their response in the presence of the color reinforced on the last trial. Whereas subjects trained on larger fixed-ratios corrected this error tendency within a trial, subjects trained on smaller fixed ratios did not.

Journal Article↗