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Biomedical subjects

J F Dardano

Publications and source records attributed to J F Dardano.

8 recordsLinked to original sources
PubMed1974

Response-produced timeouts under a progressive-ratio schedule with a punished reset option.

Three behavioral options were available to food-deprived pigeons: (1) pecking one key resulted in food reinforcement according to a 50-response progressive-ratio schedule, (2) pecking a second key reset the progressive-ratio schedule to the initial progressive-ratio step, and (3) pecking a third key produced a 3-min timeout period. Pecks on the reset key were shocked. Under low and intermediate shock intensities, timeouts were not produced; under high shock levels, timeouts were produced regularly. Timeouts occurred during the initial period of a progressive-ratio step and were more frequent during the longer steps of the progressive-ratio schedule. Response-produced timeouts under these experimental conditions could be interpreted either as an escape from aversive behavioral options or as a low-probability behavior emerging when the food reinforcement schedule exerted weaker control.

Journal Article↗
PubMed1973

Self-imposed timeouts under increasing response requirements.

Self-imposed timeouts by pigeons working under a progressive-ratio food schedule were studied under different conditions. The main findings were (1) continued production of timeouts over an extended series of sessions, (2) more frequent responding on the key with the timeout consequence than on a key having no consequence, (3) an inverse relationship between number of timeouts and level of body weight, (4) production of timeouts when the timeout duration was brief, lengthy, or controlled by the pigeon, and (5) dependence of self-imposed timeouts on variables controlling responding under the progressive-ratio schedule. Under all experimental conditions, with the exception of performances at the high body weight, timeouts were more frequent during the longer progressive-ratio steps and usually were localized in the post-reinforcement pause or the early part of the step. The timeout behavior could be interpreted as either an escape from aversive stimuli generated by the progressive-ratio schedule or as a response reinforced by the consequent stimulus change.

Journal Article↗
PubMed1972

Preference for locus of punishment in a response sequence.

Food-deprived pigeons pecked a key under a schedule in which grain was made available after the seventieth peck. In each sequence of 70 responses, either the first, middle, or final response was followed by electric shock. Before the first response of each sequence, each response on a second key changed the color of the food key and the schedule of shock that was correlated with the food key color. Each pigeon preferred a schedule of shock, in that each of the three shock schedules did not occur equally often. The preferred shock schedule and the strength of the preference varied among the pigeons. The overall rate of responding by a pigeon under a given shock schedule was directly related to the pigeon's relative preference for that schedule, except when shock after the first response in the sequence was the most preferred schedule.

Journal Article↗
PubMed1972

Variable location of punishment in a response sequence.

Key pecking of pigeons under a fixed-ratio 100, grain reinforcer schedule was followed by electric shock occurring once in each sequence of 100 responses with the shocked response varying irregularly in successive sequences. Under this shock schedule, a localized suppression of responding in a response sequence was not correlated with the probability of shock at different points in the sequence. High shock levels increased the duration of post-reinforcement pauses and suppressed responding during the first half of the response sequence. This suppression often persisted after the shocked response when shock occurred early in the sequence. The shock schedule did not produce a consistent suppressing effect on responding during the last half of the response sequence.

Journal Article↗
PubMed1971

Control of concurrent avoidance and appetitive behaviors by an indicator of shock proximity.

Two monkeys were exposed to concurrent schedules in which every fifth response on one lever had the dual consequences of delivering food and stepping a 20-step light counter upward; responses on a second lever stepped the light downward. By responding appropriately on each lever, a ration of food could be obtained without exposure to a brief shock that occurred when the counter reached the twentieth step. Behavioral patterns of light-counter control were analyzed when the monkeys were handicapped by several types of discontinuities in the 20-step counter: (1) different sets of four consecutive lights inoperative, (2) the upper or lower 10 steps inoperative, and (3) all lights inoperative. Generally, the monkeys maintained the light in the upper five steps of the 20-step light counter if the lights immediately preceding the shock position were functional. However, when these counter positions were inoperative, subjects maintained the counter around the highest operative position. With all positions of the light counter inoperative, no systematic pattern of responding on the food and avoidance levers occurred.

Journal Article↗
PubMed1970

Fractional punishment of fixed-ratio performance.

Key-peck responses of pigeons under a fixed-rate 60 (Exp. I) or fixed-ratio 99 (Exp. II) schedule of positive reinforcement were punished by response-dependent electric shock during a segment of the ratio. The punishing stimulus was scheduled in one of three locations: the first third of the ratio, the middle third, or the final third. At high shock levels, the different loci of punishment differentially affected the typical fixed-ratio performance pattern. Post-reinforcement pauses were lengthened by all punishment conditions but to a greater degree when the responses in initial third of the ratio were punished. Disruption of responses before the punished segment of the ratio was a conspicuous feature of the performances when the middle or final third of the ratio was punished. Two of the punishment conditions produced similar effects on both fixed-ratio baselines but punishing the final third of the ratio suppressed the punished responses of the ratio only with the fixed-ratio 99 schedule. General effects of all punishment conditions included consistent intra-session recoveries of partially suppressed performances, the rapid recovery of the FR performances after the punishment dependency was removed after complete suppression, and the facilitation of overall and/or local response rates of most subjects by low-intensity shock.

Journal Article↗
PubMed1968

Reversal of preference under progressive-ratio schedules by punishment.

A progressive-ratio reinforcement schedule, in which successive reinforcements required an additional 50 responses, was programmed on one key. A response on a second key reset the progressive-ratio schedule to the first step. Before punishment, all pigeons consistently reset the schedule after reinforcement on the first step, thereby minimizing the number of responses required for reinforcement. Punishment was a brief electric shock contingent upon each response on the reset key. The first effect of punishment was to change the frequency of extra responses on the reset key. Under higher intensities of punishment, the pigeons completed the advanced steps of the progressive-ratio schedule before resetting to the first step. Completions of advanced steps were accompanied by decreases in the overall rate of responding and the rate of reinforcement. When the punishment contingency was removed, the major features of pre-punishment performance were recovered.

Animals↗