摘要:

Three severely mentally retarded adolescents were studied under discrete‐trial procedures in which a choice was arranged between edible reinforcers that differed in magnitude and, in some conditions, delay. In the absence of delays the larger reinforcer was consistently chosen. Under conditions in which the smaller reinforcer was not delayed, increasing the delay to delivery of the larger reinforcer decreased the percentage of trials in which that reinforcer was chosen. All subjects directed the majority of choice responses to the smaller reinforcer when the larger reinforcer was sufficiently delayed, although the value at which this occurred differed across subjects. Under conditions in which the larger reinforcer initially was sufficiently delayed to result in preference for the smaller one, progressively increasing in 5‐s increments the delay to both reinforcers increased percentage of trials with the larger reinforcer chosen. At sufficiently long delays, 2 of the subjects consistently chose the larger, but more delayed, reinforcer, and the 3rd subject chose that reinforcer on half of the trials. These results are consistent with the findings of prior studies in which adult humans responded to terminate noise and pigeons responded to produce f

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-191

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Eight male and 8 female Wistar rats were exposed to a discrete‐trial procedure in which they chose between the presentation of a small (one pellet) or a large (three pellets) reinforcer. The delay to the small and large reinforcer was 6.0 s in the first condition of Experiment 1. Subjects consistently chose the large reinforcer. When the delay to the small reinforcer was decreased to 0.1 s in the next experimental condition, all subjects continued to choose the large 6.0‐s delayed reinforcer. When the contingencies correlated with the two levers were reversed in the next experimental condition, the majority of subjects (5 males and 6 females) still chose the large delayed reinforcer over the small immediately presented reinforcer. The delay to the small reinforcer was maintained at 6.0 s, but the delay to the large reinforcer was varied among 9:0, 15.0, 24.0, and 36.0 s in Experiment 2, in which 4 males and 4 females participated. Most subjects consistently chose the large increasingly delayed reinforcer, although choice for the small 6.0‐s delayed reinforcer developed in some females when the large reinforcer was delayed for 24.0 or 36.0 s. These choice patterns were not predicted from a literal application of a model that says choice should favor the alternative correlated with the higher (amount/delay)

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-201

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Seventeen pigeons were exposed to a three‐key discrete‐trial procedure in which a peck on the lit center key produced food if, and only if, the left keylight was lit. The center key was illuminated by a peck on the lit right key. Of interest was whether subjects pecked the right key before or after the response‐independent onset of the left keylight. Pecks on the right key after left‐keylight onset suggest control of behavior by the left keylight—an establishing stimulus. In three experiments, the strength of center‐keylight onset as conditioned reinforcer for a response on the right key was manipulated by altering the size of the reduction in time to food delivery correlated with its onset. Control of pigeons' key pecks by onset of the left keylight occurred on more trials per session when the center keylight was a relatively weak conditioned reinforcer and on fewer trials per session when the center keylight was a relatively strong conditioned reinforcer. Differences across conditions in the degree of control by onset of the establishing stimulus were greatest when changes in conditioned reinforcer strength occurred relatively frequently and were signaled. The results provide evidence of the function of an establishi

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-213

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

On a variable‐interval schedule, pecking the key to the pigeon's right (observing response) produced red or green displays relating to the delivery of grain and its dependence on pecking the key to the left (food key). During various blocks of sessions, mixed (no stimulus change) schedules including the following pairs of components were temporarily converted by the observing response to their corresponding multiple (correlated stimuli) schedules: variable‐interval 60‐s, extinction; variable‐interval 60‐s, variable‐time (response‐independent) 60‐s; extinction, variable‐time 60‐s. Differences in food delivery maintained substantial rates of responding on the observing key, without regard to pecking requirements on the food key. Although stimuli correlated with differences in the response requirement on the food key maintained higher observing rates than those maintained by uncorrelated stimuli, they were much lower than those based on food. The value of predictive stimuli as reinforcers is determined by the value of the events predicted. In particular, the cost of pecking appears to be low, and this may place limitations on the applicability of energy‐based and econom

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-229

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A concurrent‐chains schedule was used to examine how a delay to conditional discriminative stimuli affects conditioned reinforcement strength. Pigeons' key‐peck responses in the initial link produced either of two terminal links according to independent variable‐interval 30‐s schedules. Each terminal link involved an identical successive conditional discrimination and was segmented into three links: a delay interval (green), a color conditional discriminative stimulus (blue or red), and a line conditional discriminative stimulus (vertical or horizontal lines). Food delivery occurred 45 s after entering the terminal link with a probability of .5, but its conditional probability (1.0 or 0) depended on the combination of the color and the line stimuli. One of the color stimuli occurred independently of further responding, 5 s after entry into the right terminal link, but it occurred 35 s after entry into the left terminal link. One of the line stimuli occurred independently of responding 40 s after entry into either terminal link, synchronized with the offset of the color stimulus. The initial‐link relative response rate for the right was consistently higher in comparison with a control condition in which the color stimuli occurred 20 s after entry into either terminal link. The preference for the short delay to the color conditional discriminative stimuli suggests the possibility of conditioned reinforcement by information about the relation between the line conditional discriminative stimuli and the

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-239

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In two experiments, key‐peck responding of pigeons was compared under variable‐interval schedules that arranged immediate reinforcement and ones that arranged unsignaled delays of reinforcement. Responses during the nominal unsignaled delay periods had no effect on the reinforcer presentations. In Experiment 1, the unsignaled delays were studied using variable‐interval schedules as baselines. Relative to the immediate reinforcement condition, 0.5‐s unsignaled delays decreased the duration of the reinforced interresponse times and increased the overall frequency of short (<0.5‐s) interresponse times. Longer, 5.0‐s unsignaled delays increased the duration of the reinforced interresponse times and decreased the overall frequency of the short interresponse times. In Experiment 2, similar effects to those of Experiment 1 were obtained when the 0.5‐s unsignaled delays were imposed upon a baseline schedule that explicitly arranged reinforcement of short interresponse times and therefore already generated a large number of short interresponse times. The results support earlier suggestions that the unsignaled 0.5‐s delays change the functional response unit from a single key peck to a multiple key‐peck unit. These findings are discussed in terms of the mechanisms by which contingencies control response structure in the absence of specific struct

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-249

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In a procedure intended to determine color preference in pigeons (which partially replicated Catania, Owens,&von Lossberg, 1983), two keys were illuminated by different colors drawn from a set of amber, red, green, or blue stimuli; this was followed by the presentation of grain when either of the two colors was pecked. The grain was illuminated alternately across trials with the colors presented on the keys. In Experiment 1 the intensity of the color stimuli used was not equalized, whereas in Experiment 2 the intensity of the colors was equalized. The low preference for blue found in Experiment 1, as measured by differential key pecking, was not found in Experiment 2. The discriminability of the intensity‐equalized colors was confirmed in Experiment 2a, in which equal‐intensity color discrimination problems were presented. In Experiment 3, as in Catania et al. (1983), a response‐independent reinforcement schedule was used, but with intensity‐equalized colors. In contrast to Experiment 2, very low preference for blue was found here and in Experiment 4, which used a within‐subject procedure. These findings suggest that pigeon color preference may be a function of intensity, but all controlling variables have not as yet been i

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-265

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Rats repeatedly acquired the performance of selecting only the four baited arms in an automated eight‐arm radial maze, with the arms containing food pellets randomly assigned prior to each session. During each 14‐trial (trial: obtain all four pellets) daily session, the number of errors (selecting nonbaited arms or repeating arm selections) showed a within‐session decline, and choice accuracy for the first four arm selections showed a positive acceleration across trials for all rats. An index‐of‐curvature statistic, calculated for total errors, was used to quantify both the within‐ and between‐session improvement of performance. Scopolamine (0.03 to 0.3 mg/kg, ip), but not methylscopolamine (0.3 mg/kg), reduced the accuracy of the first four selections of each trial and increased total within‐session errors for all rats. Session times also were increased by scopolamine. An examination of within‐session accuracy showed only slight signs of improvement at the higher dosages of scopolamine. The results indicate that behavior in transition states maintained by reinforcement contingencies in the radial maze is similar to that maintained by extended chained schedules, despite the fact that some of the stimuli controlling behavior in the maze are absent at the moment be

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-275

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Transition‐state choice behavior of pigeons was examined in two experiments designed to test predictions of melioration and the kinetic model. Both experiments began with an initial training condition during which subjects were maintained on concurrent variable‐interval schedules. In Experiment 1, subjects were then exposed to concurrent variable‐ratio schedules, whereas in Experiment 2, subjects were then exposed to concurrent extinction. Contrary to the predictions of melioration, but consistent with the kinetic model, acquisition of preference on concurrent variable‐ratio schedules followed a negatively accelerated logistic trajectory, and preference remained stable in concurrent extinction. Predictions made by the kinetic model concerning rates of switching between alternatives were also su

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-291

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

There is continuing controversy about the behavioral process or processes that underlie the major regularities of free‐operant choice such as molar matching and systematic deviations therefrom. A recent interchange between Vaughan and Silberberg and Ziriax concerned the relative merits of melioration, and a computer simulation of molecular maximizing. There are difficulties in evaluating theories expressed as computer programs because many arbitrary decisions must often be made in order to get the programs to operate. I therefore propose an alternative form of, model that I termquasi‐dynamicas a useful intermediate form of theory appropriate to our current state of knowledge about free‐operant choice. Quasi‐dynamic models resemble the game‐theoretic analyses now commonplace in biology in that they can predict stable and unstable equilibria but not dynamic properties such as learning curves. It is possible to interpret melioration as a quasi‐dynamic model. An alternative quasi‐dynamic model for probabilistic choice,ratio invariance, has been proposed by Horner and Staddon. The present paper compares the predictions of melioration and ratio invariance for five experimental situations: concurrent variable‐interval variable‐interval schedules, concurrent variable‐interval variable‐ratio schedules, the two‐armed bandit (concurrent random‐ratio schedules), and two types of frequency‐dependent schedule. Neither approach easily explains all the data, but ratio invariance seems to provide a better picture of pigeons' response to probabilistic choice procedures. Ratio invariance is also more adaptive (less susceptible to “traps”) and closer to the original expression of the law of effect than pure hill‐climbing processes such as momentary maximizing and melioration, although such processes may come in to play on more complex procedures that provide opportun

ISSN:0022-5002    

DOI:10.1901/jeab.1988.49-303

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY