ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-493

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Three pigeons were trained to discriminate a 5.0 mg/kg dose of pentobarbital from saline under a two‐key concurrent schedule with responding on the key associated with the presession injection, under both stimulus conditions, producing four times as many reinforcers as responding on the other key. This concurrent schedule resulted in approximately 70% responding to the higher reinforcement key under the pentobarbital stimulus and approximately 30% responding to that key under the saline stimulus. During testing, then, the pigeons were able to dose‐dependently emit higher (>70%) or lower (<30%) values than were established under the control conditions. Dose—response curves were determined for pentobarbital (twice), methamphetamine, phencyclidine, chlordiazepoxide, and the combination of pentobarbital and the barbiturate antagonist bemegride. The results obtained with pentobarbital and chlordiazepoxide showed that, as the dose increased, pentobarbital‐appropriate responding also increased. Methamphetamine produced relatively flat dose—response curves, whereas phencyclidine administration produced inconsistent effects on responding. The combination of the training dose of pentobarbital with increasing doses of bemegride produced a decrease in pentobarbital‐appropriate responding. The results also showed that the dose—response curves for pentobarbital and chlordiazepoxide, instead of being all or none, were graded functions of

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-495

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Pigeons were trained on a multiple schedule of reinforcement in which separate concurrent schedules occurred in each of two components. Key pecking was reinforced with milo. During one component, a variable‐interval 40‐s schedule was concurrent with a variable‐interval 20‐s schedule; during the other component, a variable‐interval 40‐s schedule was concurrent with a variable‐interval 80‐s schedule. During probe tests, the stimuli correlated with the two variable‐interval 40‐s schedules were presented simultaneously to assess preference, measured by the relative response rates to the two stimuli. In Experiment 1, the concurrently available variable‐interval 20‐s schedule operated normally; that is, reinforcer availability was not signaled. Following this baseline training, relative response rate during the probes favored the variable‐interval 40‐s alternative that had been paired with the lower valued schedule (i.e., with the variable‐interval 80‐s schedule). In Experiment 2, a signal for reinforcer availability was added to the high‐value alternative (i.e., to the variable‐interval 20‐s schedule), thus reducing the rate of key pecking maintained by that schedule but leaving the reinforcement rate unchanged. Following that baseline training, relative response rates during probes favored the variable‐interval 40‐s alternative that had been paired with the higher valued schedule. The reversal in the pattern of preference implies that the pattern of changeover behavior established during training, and not reinforcement rate, determined the prefer

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-513

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

In two experiments, rats living in a closed economy were offered continuous, concurrent access to four resources: food, water, a nest, and a running wheel. Costs of consuming food and water were imposed with bar‐press requirements, and the price of either one or both resources was raised. As the consumption cost increased, less was consumed in each bout of resource use. Bout frequency increased, but not sufficiently to compensate for the fall in bout size, and total intake fell. Food and water tended to be complementary resources, in that as intake of one fell with its price, intake of the other also decreased. This interaction was accounted for by the defense of the ratio of body water to lean body mass. As amount consumed decreased, increases in feed efficiency (weight gain per unit of food ingested) and the use of stored calories compensated for the reduced energy intake. There was evidence of competition between feeding and drinking at the higher costs: When both commodities were expensive, the decline in the intake of each one was greater than when only one commodity was expensive. Although the time spent nesting, running, and in unmonitored activity was adjusted when feeding or drinking took more of the rat's day, there was no particular activity that was sacrifice

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-527

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Response‐independent food was delivered during a dark‐key phase between two multiple‐schedule components to explore its disruptive effects on responding. Responding in components was maintained by separate variable‐interval 120‐s schedules, with a 2‐s reinforcer in Component 1 and a 6‐s reinforcer in Component 2. Across conditions the rate and duration of response‐independent food presentations were manipulated. The results showed that response rates in both components decreased as a function of the duration and the rate of response‐independent food presentations; moreover, the decrease in response rate relative to the baseline level was larger in Component 1 than in Component 2. These findings were consistent with expectations from behavioral momentum theory, which predicts that if equal disruption (response‐independent food in this case) is applied to responding in two components, then the ratio of response‐rate change in Component 1 versus Component 2 should remain constant, irrespective of the magnitu

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-549

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Four pigeons were trained to discriminate between two line orientations in a two‐alternative forced‐choice procedure. The distribution of reinforcers for the two types of correct response was varied across conditions. Performance on each trial was recorded separately, including the time taken to make a choice response. Discriminability and response‐bias measures were calculated for overall performance, and, following a median split of the data from each condition, for faster and slower choice responses in each condition. Discriminability between the stimuli did not vary systematically as a function of choice latency. Variations of the reinforcer distributions produced larger response biases for the faster responses than for the slower responses. Responses on trials following reinforcers were faster and showed a greater effect of the reinforcer distribution than did other responses. Behavioral models of signal detection should consider the speed of the choice response as a factor modulating the effects of reinforcer distribu

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-561

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Three experiments used pigeons in an autoshaping procedure and a single‐subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response‐independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single‐subject de

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-575

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Experimental parameters were adjusted so that pigeons' pairwise choices among three alternatives reflected the following order of preference: (a) a smaller‐sooner reinforcer, (b) a larger‐later reinforcer, and (c) the smaller‐sooner reinforcer followed by a punishment (consisting of an extended blackout period). After this order of preference was established, the pigeons were exposed to a two‐link, concurrent‐chain‐like choice procedure. One terminal link consisted of a choice between the smaller‐sooner and the larger‐later reinforcer; the other terminal link was identical to the first except that the smaller‐sooner reinforcer was followed by blackout punishment. The pigeons' preference (in their initial‐link choice) for the terminal link with the punished smaller‐sooner alternative increased as the delay between the initial and terminal links increased. By choosing this terminal link, the pigeons are said to have “committed” themselves to obtaining the larger‐later reinforcer. However, unlike prior studies of commitment (e.g., Rachlin&Green, 1972), it was still possible after making the commitment for the pigeons to choose the smaller‐sooner reinforcer and undergo the punishment. The pigeons did in fact occasionally make t

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-593

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Two experiments used response‐initiated delay schedules to test the idea that when food reinforcement is available at regular intervals, the time an animal waits before its first operant response (waiting time) is proportional to the immediately preceding interfood interval (linear waiting; Wynne&Staddon, 1988). In Experiment 1 the interfood intervals varied from cycle to cycle according to one of four sinusoidal sequences with different amounts of added noise. Waiting times tracked the input cycle in a way which showed that they were affected by interfood intervals earlier than the immediately preceding one. In Experiment 2 different patterns of long and short interfood intervals were presented, and the results implied that waiting times are disproportionately influenced by the shortest of recent interfood intervals. A model based on this idea is shown to account for a wide range of results on the dynamics of timing behavio

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-603

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Three experiments explored the influence of prechoice events on pigeons' preference. In two of three studies, a fixed‐interval 200‐second prechoice period preceded the initial links of a concurrent chain in which outcomes differed either (a) in terms of the delay to food or (b) in terms of amount of food and delay to food. In Experiment 3, the prechoice period preceded the initial links that provided a choice between a small single food presentation and two identical, more delayed food presentations. In all three cases, obtained choice proportions did not vary as a function of prechoice duration. These results suggest that a local‐contextual view adequately describes the foraging context; they also have implications for the appropriate formulation of the delay‐reduction theory of conditioned reinforcement and rate‐maximizing views of optimal foragi

ISSN:0022-5002    

DOI:10.1901/jeab.1996.65-619

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY