Context extinction following conditioning with delayed reward enhances subsequent instrumental responding.

In Experiment 1, delayed reward generated low response rates relative to immediate reward delivered with the same frequency. Lister rats exposed to delayed reward subsequently responded at a higher rate in extinction if they received nonreinforced exposure to the conditioned context after instrumental training and prior to test, compared with animals that received home cage exposure. In Experiment 2, a signaled delay of reinforcement resulted in higher rates than an unsignaled delay. Nonreinforced exposure to the conditioning context elevated response rate for subjects in the unsignaled condition relative to a home cage group, but had no effect on response rates for subjects that had received the signaled delay. In Experiment 3, following an unsignaled reinforcement delay, groups receiving either no event or signaled food in the context responded faster in extinction than groups receiving no context exposure or unsignaled food. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attenuation and enhancement of instrumental responding by signals for reinforcement on a variable interval schedule.

In three experiments we used pigeons responding on a variable interval schedule to examine the effects of signaling reinforcement on instrumental performance. Using a four-component multiple schedule, we found in Experiment 1 that when reinforcement was delayed by 0.5 s for two of the components, response rates were attenuated by signaling reinforcement relative to performance in the unsignaled delay condition. A delay of 3 s in the remaining two components resulted in an enhancement of responding when the delay was signaled. An enhancement of responding occurred when we used a scheduled 0.5-s delay when the procedure ensured that responding was prevented during the delay interval by extinguishing the keylight (Experiment 2) or by resetting the delay timer when responses were emitted during the delay (Experiment 3). These results are discussed with reference to the theories of signaling reinforcement during instrumental responding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counterconditioning versus forced exposure in extinction of avoidance responding and conditioned fear in rats.

Conducted 2 experiments using 64 and 32 male Long-Evans hooded rats, respectively. Exp. I investigated the extinction of the conditioned avoidance response (CAR) by response prevention and counterconditioning methods. Response prevention was most effective in extinguishing both the CAR and associated conditioned fear, although counterconditioning produced greater extinction than the regular extinction procedure. Exp. II equated the counterconditioning and response-prevention conditions for duration of CS exposure and demonstrated the superiority of the latter in extinguishing the CAR; both methods were equally effective in decreasing conditioned fear as compared to the regular extinction procedure. Extinction of the CAR was facilitated to the extent to which different procedures eliminated response-contingent feedback by reducing escape-avoidance responses. Conditioned fear was a function of the amount of nonreinforced exposure to the CS during extinction. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shock-induced suppression and potentiation of instrumental responding by rats.

A total of 20 female Long-Evans rats trained to press a retractable lever for food in a discrete trials situation were subsequently punished for responding. After suppression of responding, response-independent shocks were presented, with intensity increased on successive daily sessions. Shock induced responding, and number of responses, increased and response latencies decreased with increasing shock intensity. Control Ss initially given uncorrelated lever-food presentations responded significantly less to response-independent shock, and their responding was not systematically related to shock intensity. Results are consistent with the view that shock induces or disinhibits prepotent responses and inconsistent with the view that, to be effective in suppressing behavior, punishment must induce responses incompatible with the punished response. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postconditioning devaluation of a reinforcer affects instrumental responding.

Three experiments with 68 male Holtzman rats investigated performance of an instrumental response following postlearning changes in the value of the reinforcer, using a within-S design. Exps I and II used a conditioning manipulation (pairing with a toxin), and Exp III employed a motivational procedure (satiation) to reduce the reinforcer value. In both cases, performance of the instrumental response was substantially attenuated during a subsequent extinction test. Results suggest that these devaluation effects are mediated by the instrumental contingency and that a reasonably detailed representation of the reinforcer is encoded in instrumental learning. (38 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Feedback stimuli and the extinction of avoidance responding in rats.

Trained 24 female Wistar rats to avoid electric shock in a 2-way shuttlebox with a feedback stimulus contingent upon each avoidance response in order to investigate extinction of the avoidance response. Shock presentations were then discontinued. Results indicate that the temporal relationship of the avoidance response and feedback was disrupted by continuously presenting the feedback stimulus or by random presentations of the stimulus. These procedures prolonged extinction relative to complete withdrawal of the feedback, but enhanced extinction relative to response contingent presentations of the feedback. Parallels between patterns of extinction found with these procedures and those found with appetitive reinforcers are discussed. (French abstract) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-concept and expectancy for social reinforcement in noninstitutionalized male homosexuals.

Selected a total of 80 college-educated, socially-functioning homosexual males (including teachers and other professionals) with high or low scores on the Tennessee Self Concept Scale. Ss guessed at the frequency of smiling and angry faces, a task adapted from D. Rosenhan and S. Messick's (see record 1966-02293-001) study of heterosexual males. Results provide evidence for the interaction of self-concept and the sex of the expected faced, and the tendency to over- and underestimate the number of faces. The significant Sex * Dominant Input (the measure of expectancy) interaction was contingent on self-concept. Results are comparable to those of Rosenhan and Messick, suggesting that the generalization that male homosexuals have a preference for objects of the same sex (based on a high expectancy for negative reinforcement from female figures) may need qualification or revision. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversive schedules with independent probabilities of reinforcement for responding and not responding by rhesus monkeys: II. Without signal.

Manipulated independently the probabilities of aversive stimulus presentation given the occurrence or the nonocurrence of a leverpress response. 10 naive male rhesus monkeys (Macaca mulatta) were divided into 5 groups, each group receiving a different sequence of the 2 probabilities and thereby a different sequence of electric shock presentation schedules ranging between avoidance and punishment. The schedules provided systematic control both of the amount of response facilitation that occurred when response-produced shocks were first introduced following avoidance training and of the postfacilitation response rate decline. When the probability of shock presentation following a response was less than that for not responding, scalloped response patterns occurred; when the relative shock probabilities were reversed, bipeak response patterns were observed. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DRL performance, extinction, and secondary reinforcement: Role of appetitive value of food in mice with septal lesions.

Conducted 5 experiments with a total of 116 B6D2F-sub-1/J mice. Normal Ss and Ss with septal lesions were trained on a DRL 8-sec schedule for food reinforcement varying in incentive value. Dilution of diet increased the number of reinforcements received by Ss with septal lesions. In Exps II and III the effects of septal lesions on resistance to extinction after continuous reinforcement training and the strength of secondary reinforcement were investigated. Changes in reinforcement value modified the septal lesion effects in both cases. All 3 experiments demonstrated the alteration of the septal lesion effect through a change in the appetitive value of the reinforcement. Results suggest that one of the mechanisms by which septal lesions impair DRL performance is an enhancement of reinforcing properties of food. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversive schedules with independent probabilities of reinforcement for responding and not responding by rhesus monkeys: I. With signal.

Applied 2 independent probabilities of electric shock presentation to 12 naive male rhesus monkeys (Macaca mulatta) as the independent variables defining schedules of aversive control: (a) the probability that a fixed signal period would end with a shock if a specified response were made and (b) the probability that the fixed signal period would end with shock if a specified response were not made. Systematic changes in the probability values generated several familiar schedules of aversive control, as well as several intermittent procedures. Response rate tended to rise during the signal period when the probability values were set so that not responding was more likely to produce a shock than responding; response rate tended to fall during the signal period when the probabilities were set so that responding was more likely to produce shock than not responding. Response patterning in time was also evident during the interval between signals when no consequences were programmed. These characteristics of response patterning reflected the changes in the 2 independent probability variables in ways that simple measures of response rate and shock rate alone did not. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of instrumental learning in tolerance to cathinone hypophagia.

The effects of dl-cathinone on milk intake and motor activity were investigated in bottle- and cannula-fed rats. Acute injections of cathinone produced dose-dependent increases in activity in both groups but only produced decreased intake in bottle-fed rats. With chronic injections, tolerance to the suppression of intake developed in the bottle-fed group, accompanied by decreased activity. After the tolerance phase, switching from bottle to cannula feeding produced further increases in intake, whereas switching from cannula to bottle feeding produced decreased intakes. These results suggest that (a) cathinone suppresses intake by inducing locomotion and stereotypy, which interfere with the appetitive phase of feeding, and (b) tolerance to drug-induced hypophagia involves learning to suppress such movements, as proposed by the instrumental learning model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delay of reinforcement in instrumental discrimination learning of rats.

Assigned 4 groups of 8 male albino rats each to a 2-choice discrimination task. Ss were reinforced for pressing 1 lever in the presence of 1 auditory stimulus and for pressing an alternative lever in the presence of a 2nd auditory stimulus. Acquisition of the discrimination was retarded when reinforcement was delayed for all or a random half of the correct responses in the presence of each stimulus. However, performance was facilitated when reinforcement was delayed for all of the correct responses in the presence of 1 stimulus but not the other. Results are interpreted in terms of both classical and operant mediational processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adolescents exhibit behavioral differences from adults during instrumental learning and extinction.

Adolescence is associated with the development of brain regions linked to cognition and emotion. Such changes are thought to contribute to the behavioral and neuropsychiatric vulnerabilities of this period. We compared adolescent (Postnatal Days 28–42) and adult (Postnatal Day 60+) rats as they performed a simple instrumental task and extinction. Rats were trained to poke into a hole for a food-pellet reinforcer. After six days of training, rats underwent extinction sessions in which the previously rewarded behavior was no longer reinforced. During extinction, we examined the effects of continued presentation of a cue light and food restriction. Adults and adolescents exhibited similar performance during training, although adolescents made more task-irrelevant pokes, consistent with increased exploration. Adults made more premature pokes, which could indicate a more exclusive focus on the task. During extinction, adolescents made more perseverative (previously reinforced) pokes than adults. This behavior was strongly modulated by the combination of motivational factors present (food restriction and cue light), indicating that adolescents were differentially sensitive to them. Furthermore, food restriction induced greater open-field activity in adolescents but not in adults. Thus, as the neural circuitry of motivated behavior develops substantially during adolescence, so too does the behavioral sensitivity to motivational factors. Understanding how such factors differently affect adolescents may shed light on mechanisms that lead to the development of disorders that are manifested during this period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression and perception of reinforcement: Lack of differences in expectancy change among alcoholics.

62 male alcoholic inpatients (mean age 43.55 yrs) were administered the Beck Depression Inventory and the chance and skill tasks previously employed to investigate the perception of reinforcement within the learned helplessness model of depression. Three groups differing in level of depression were composed. The dependent measures were expectancy statements for future success within both the skill and chance tasks. The data were analyzed using a 3 by 2 ANOVA with repeated measures across tasks. No significant Depression Task interactions were obtained. The major proportion of behavioral variance in the analyses appeared to be accounted for by the salience of task characteristics. The implication for the learned helplessness model and the interaction of alcoholism and depression are discussed. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus control in instrumental discrimination learning and reinforcement schedule situations.

Investigated ways in which control is exercised over responding by cues associated with reinforcement (RC) as well as nonreinforcement (NC) in discrimination tasks. In Phase 1 of Exp I, with 20 male albino Holtzman rats, either RC or NC was reinforced. In Phase 2, RC and RN were employed as the brighter stimulus (S+) and the less bright stimulus (S–) cues. Results show that differential responding developed less rapidly when the cue reinforced in Phase 1 was the S– rather than the S+ cue in Phase 2, regardless of whether that cue was RC or NC. In Exp II, using 16 male albino Holtzman rats, the S+ cue was a compound of a hedonic cue and a brightness cue, as was the S– cue. Differential responding developed less rapidly when the hedonic cue reinforced in S– was the same as that reinforced in S+, again regardless of whether the cue was RC or NC. Results show that both cues regulated responding and that neither was frustrating to Ss. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversive schedules with independent probabilities of reinforcement for responding and not responding by rhesus monkeys: III. Recovery of avoidance baseline.

Investigated the effect of prior response history on subsequent avoidance responding. In Exps I and II, using 12 and 10 male rhesus monkeys that had served in previous experiments by the authors (see PA, Vol 53:Issue 6), up to 5 sequences of aversive stimulus presentation schedules provided a range from no responding to complete avoidance response recovery, whether with or without signaled shock. Exp III, with 12 naive rhesus monkeys, demonstrated that the same range of avoidance response recovery could be obtained by the use of only selected schedules rather than a prolonged sequence. These findings provide further support for the power of 2 independent probability variables, governing reinforcement delivery for responding or nonresponding, for generating schedules of reinforcement. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of expectancy manipulation in systematic desensitization.

Manipulated expectancy, relaxation, and hierarchy content in a 2 * 2 design with 2 additional control groups. Ss were 76 spider-phobic undergraduates. It was hypothesized that a major portion of therapeutic change following desensitization could be accounted for by the Ss' responses to positive feedback inherent in the paradigm. Ss saw either photographs of spiders or blank slides that they believed to be tachistoscopically-presented pictures of spiders. One-half of the Ss believed their progress through the hierarchy to be contingent on autonomic responses; the others believed rate of progress to be random. Findings did not support the hypothesis that expectancy is the only factor in desensitization, but they did clarify the role of expectancy vis-a-vis the counterconditioning elements typically discussed in the literature. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of experience on agonistic responding: an expectancy theory interpretation

The mammary glands of ten still-birth premature fetuses were studied histologically. In seven cases a combination of oestrogen-progesterone preparations were administered to the mother in early pregnancy for a duration of at least 3 months. In three cases no hormones were administered. According to our observations and the experimental work of other investigators, we may conclude that oestrogenic hormones inhibit the development of the mammary gland.     

Contingency management treatment of outpatient unipolar depression: A comparison of reinforcement and extinction.

This study examined the differential effects of reinforcement versus extinction in contingency management of outpatient unipolar depression for 6 depressed subjects and their significant others. We used an alternating-treatments design (with a multiple baseline across subjects) to provide subjects with 4 weeks of reinforcement for a targeted deficit and 4 weeks of extinction for a targeted excess. The results (a) confirmed the efficacy of contingency management, administered by significant others, for outpatient unipolar depression; (b) demonstrated the predicted behavior change and decreased depression for both reinforcement and extinction; and (c) showed that responses covaried in an individualistic manner across subjects and varied across reinforcement and extinction. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Focus of attention, chronic expectancy, and responses to a feared stimulus.

Tested an attentional model of fear-based behavior with 44 undergraduates. It was predicted that among Ss with moderate fear of snakes, heightened self-attention during an approach attempt would cause increased awareness of existing anxiety, followed by 1 of 2 courses of events: Ss who believed that they could do the behavior in spite of their fear were expected to redirect their attention to the behavior–goal comparison and exhibit no behavioral deficit. Ss who doubted their ability to do the behavior were expected to divert their attention from the behavior–goal comparison and to withdraw behaviorally from the approach attempt. Results support this reasoning and discussion centers on relationships between the proposed model and previous theory. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)