摘要:

With reinforcement contingent on a single peck on either of two available keys (concurrent continuous reinforcement schedules) 4 pigeons, at 80% of free‐feeding weights, preferred a smaller‐sooner reinforcer (2.5 s of mixed grain preceded by a 0.5‐s delay) to a larger‐later reinforcer (4.5 s of mixed grain preceded by a 3.5‐s delay). However, when the smaller‐sooner and larger‐later reinforcers were contingent on a concurrent fixed‐ratio 31 schedule (the first 30 pecks distributed in any way on the two keys), all pigeons obtained the larger‐later reinforcer much more often than they did when only a single peck was required. This “self‐control” was achieved by beginning to peck the key leading to the larger‐later reinforcer and persisting on that key until reinforcement occurred. We call this persistence “soft commitment” to distinguish it from strict commitment, in which self‐control is achieved by preventing changeovers. Soft commitment also effectively achieved self‐control when a brief (1‐s) signal was inserted between the 30th and 31st response of the ratio and with concurrent fixed‐interval 30‐s schedules (rather than ratio schedules) of reinforcement. In a second experiment with the same subjects, the fixed ratio was interrupted by darkening both keys and lighting a third (center) key on which pecking was required for various fractions of the fixed‐ratio count. The interruption significantly reduced self‐control. When interruption was complete (30 responses on the center key followed by a single choice response), pigeons chose the smaller‐sooner reinforcer as frequently as they did wh

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-117

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Twelve subjects were trained to select one of two stimuli from a pair (the B pair) when presented with one of two stimuli from another pair (the A pair), thus establishing two AB relations, A1‐B1 and A2‐B2. In a similar fashion, additional stimuli were used to establish BC, CD, and DE relations. Trials used to train all relations occurred in each session. Once performances were established, probe trials were introduced that tested for the emergence of untrained relations (e.g., B1‐D1 or A1‐E1). These emergent relations were categorized according to nodal distance (i.e., the number of stimuli across which transitivity would have to hold in order for the relation to emerge). For example, a test for A2‐C2 crosses one node (B2), whereas a test for A1‐E1 crosses three nodes (B1, C1, and D1). Only 2 of the subjects formed equivalence classes. The evocation of class‐appropriate responding by each emergent‐relation probe was an inverse function of nodal distance for all 12 subjects. In addition, performance on the originally trained relations was disrupted by the introduction of probes. The 2 subjects who exhibited equivalence classes were then trained to make different numbers of key presses in the presence of each of the four A and E stimuli. In a response‐transfer test, the B, C, and D stimuli evoked the responses trained to the A and E stimuli in the same equivalence class. Likelihood of class‐appropriate responses was an inverse function of nodal distance, and this pattern persisted across testing. Reaction times in the transfer test were an inverted U‐shaped function of nodal distance. Because training of the baseline relations occurred concurrently and the B, C, and D stimuli were presented an equal number of times before the transfer test, the test performances illustrate effects of nodal distance that were not confounded by order or amount of experience with the stimuli. The results imply that ordered, sequential exposure to individual stimulus relations may facilitate the development of equivalence classes and that the relatedness of stimuli within an equivalence class is a relatively permanent inverse funct

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-129

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Six homing pigeons were trained on a variety of concurrent variable‐interval schedules in a switching‐key procedure. Unlike previous work, reinforcer ratios of up to 160 to 1 and concurrent extinction variable‐interval schedules were arranged in order to investigate choice when reinforcer‐frequency outcomes were extremely different. The data obtained over 11 conditions were initially analyzed according to the generalized matching law, which fitted the data well. The generalized matching law was then fitted only to conditions in which the reinforcer ratios were between 1 to 10 and 10 to 1. The deviations of choice measures from the other four more extreme reinforcer‐ratio conditions were significantly more towards equal choice than predicted by this second generalized matching fit. A contingency‐discriminability model, which predicts such deviations, described the data more effectively than did the generalized matching law, and also correctly predicted the maintenance of responding on both alternatives when one was associated with

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-147

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In Experiment 1, 2 experimental subjects were given pretraining of nonarbitrary relations that brought their responses under the control of four contextual stimuli; same, opposite, more than, and less than. One control subject was not exposed to this pretraining. The 2 pretrained subjects and the 3rd nonpretrained subject then received training in six arbitrary relations, the following four relations being the most critical: same/A1‐B1, same/A1‐C1, less than/A1‐B2, more than/A1‐C2. All 3 subjects were then tested for seven derived relations, the following three relations being the most important: same/B1‐C1, more than/B1‐C2, less than/B1‐B2. The 2 pretrained subjects, but not the nonpretrained subject, showed the derived relations. One of the stimuli (B1) from the relational network and two novel stimuli (X1 and X2) were then used to train three different self‐discrimination responses on three complex schedules of reinforcement. That is, all 3 subjects were trained to pick X1 if they had not emitted a response, to pick B1 if they had emitted one response only, and to pick X2 if they had emitted two responses only. The 2 pretrained subjects, but not the nonpretrained subject, showed the predicted transformation of self‐discrimination response functions in accordance with the relations of sameness, more than, and less than (i.e., no response, pick B2; one response only, pick C1; and two responses only, pick C2). In Experiment 2, 2 new subjects were employed, and the arbitrary relational training and testing phases were modified to control for a procedural artifact that may have contributed to the results of the first experiment. Experiment 2 replicated the findings of Experiment 1. The pattern of results support the utility of a relational frames approach to understanding derived s

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-163

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In a successive discrimination, red and green hues signaled component variable‐interval schedules. The exponent of the power function relating ratios of responses in the red and green components to ratios of reinforcers provided a reinforcement‐free measure of discrimination or stimulus control. Responses were recorded in successive 10‐s subintervals of the 50‐s components. The power‐function exponent decreased systematically with increasing time since component transition in most conditions of five experiments. This reduction was not influenced by the absolute rate of reinforcement, consistent with the interpretation of the exponent as a measure of stimulus control. A reduction in the overall level of stimulus control by increasing the duration of response‐produced keylight offset did not influence the decrease in discrimination with increasing time since component transition. The results support the conclusion that discriminative responding in successive discriminations is governed by several sources of stimulus control including delayed control by component

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-185

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Pigeons were trained in a discrete‐trial task in which a response to the center key obtained illumination of a side key and a single response to the side key terminated a trial with either reinforcement or nonreinforcement. Center‐key speeds (i.e., reciprocals of latencies) declined with increases in intertrial interval, and it is argued that this effect is related to a decreased likelihood as intertrial interval increases that birds will be near the key at trial onset. Side‐key speeds on trials with reinforcement decreased both with increases in intertrial interval and with shifts from continuous reinforcement to either a discrimination or a partial‐reinforcement condition. The effects on side‐key speeds are compared with effects observed in alley‐running tasks using rats, and an interpretation in terms of frustration theory is offered for the results obtained in both ty

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-215

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two‐alternative free‐operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50‐s trial was reinforced at variable intervals, and variable‐interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right‐key response proportions in consecutive 5‐s bins of the 50‐s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right‐key responses, and were longest when the differential reinforcer rate most strongly favored left‐key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relativ

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-225

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Three pigeons pecked keys and 5 rats pressed levers for food delivered on variable‐interval schedules. During baseline conditions, subjects responded on a variable‐interval 40‐s schedule throughout the session. During experimental conditions, the programmed rate of reinforcement changed every 10 min in the 50‐min sessions. When rats served as subjects, Herrnstein's (1970) hyperbolic equation provided a good description of the relation between rate of responding during a 10‐min interval and the rate of reinforcement obtained during that interval. Responding, measured over 10‐min blocks, was also approximately equally sensitive to changes in the programmed rate of reinforcement at all times in the session. Herrnstein's equation provided a poorer description of the changes in responding when pigeons served as subjects. Differences in experimental experience or differences in the absolute rates at which subjects responded may have contributed to the differences in results for these differ

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-237

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1995.64-247

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY