摘要:

Two pigeons were trained to discriminate a grating stimulus from a blank stimulus of equivalent luminance in a three‐key chamber. The stimuli and blanks were presented behind a transparent center key. The procedure was a conditional discrimination in which pecks on the left key were reinforced if the blank had been present behind the center key and pecks on the right key were reinforced if the grating had been present behind the center key. The spatial frequency of the stimuli was varied in each session from four to 29.5 lines per millimeter in accordance with a variation of the method of constant stimuli. The number of lines per millimeter that the subjects could discriminate at threshold was determined from psychometric functions. Data were collected at five values of stimulus luminance ranging from −0.07 to 3.29 log cd/m2. The distance from the stimulus to the anterior nodal point of the eye, which was determined from measurements taken from high‐speed motion‐picture photographs of three additional pigeons and published intraocular measurements, was 62.0 mm. This distance and the grating detection thresholds were used to calculate the visual acuity of the birds at each level of luminance. Acuity improved with increasing luminance to a peak value of 0.52, which corresponds to a visual angle of 1.92 min, at a luminance of 2.33 log cd/m2. Further increase in luminance produced a small decline in

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-129

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Nine pigeons were trained to discriminate a moving stimulus from a stationary stimulus. In one experiment, the stimulus was a rotating disc with radial stripes. In a second experiment, the stimulus was a vertically moving film strip with horizontal bars. Several psychophysical procedures were used to determine the minimal detectable velocity of movement. The detection thresholds for most of the pigeons fell in the range of 4.4 to 6.5 millimeters per second, corresponding to a retinal velocity of 4.1 to 6.01 degrees per second. a signal‐detection analysis of the psychophysical data indicated systematic changes in response bias that were related to the ordinal position of the stimulus velocity in the sequenc

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-143

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Key pecking of three pigeons was studied under a conjunctive schedule that specified both a fixed‐interval and an adjusting fixed‐ratio requirement. The fixed‐interval schedule was 6 min for one pigeon and 3 min for the other two. The size of the ratio requirement was determined within each cycle of the fixed interval by the duration of the pause before responding began. The fixed‐ratio value was at maximum at the start of each fixed interval and decreased linearly until the first response occurred (adjusting fixed‐ratio schedule). A peck produced food when the number of responses remaining on the fixed‐ratio schedule was completed and when the fixed interval had elapsed. If no response occurred during the interval, the fixed‐ratio requirement decreased to one and a single response after the interval elapsed produced food. The initial value of the adjusting fixed‐ratio schedule was studied over a range of 0 to 900. Increases in the adjusting fixed‐ratio schedule to about 300 responses increased both pause duration and running response rate and also modified the pattern of responding from that obtained under the fixed‐interval schedule. Higher values of the adjusting fixed ratio generally decreased pause duration and running response rate and also disrupted responding. Interreinforcement time under the conjunctive schedule was increased substantially when the adjusting fixed‐ratio size e

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-157

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Three experiments investigated conditions affecting the choice to cooperate or compete. Experiment i compared the effects first of an individual activity, then of a competitive task as an alternative to cooperation. For both comparisons, subjects could earn more by cooperating. Choice of competition, but not individual activity, was found to depend on the task choice contingencies. Competition predominated when both subjects could compete if either or both chose competition. Previously competitive pairs cooperated when both subjects could cooperate if either or both chose cooperation. Experiment ii investigated the effects of differences in magnitude of the reinforcers for cooperating or competing. Choice between the two alternatives was manipulated in all pairs by varying reinforcer difference. Competition was chosen over cooperation only within the limits within which competition was potentially profitable. Experiment iii replicated the findings of Experiment ii using triads. Subjects in triads, however, were more likely to withdraw from the experiment. Thus, the data for pairs and triads suggest an orderly relation between reinforcer difference for cooperating or competing and task choice. Motivation of subjects to maximize relative gain by competing can be overridden by moderate reinforcer differences favoring cooperation.

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-165

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Pigeons' standing on a platform produced food reinforcement according to two‐component multiple schedules in which either both components consisted of the same variable‐interval schedule or one of these was replaced with a component without reinforcement (extinction). The components of the multiple schedule alternated every 30 sec, and were signalled by changes in the color of diffuse overhead illumination. Changing the schedule of one of the components to extinction increased the percentage of time spent on the platform during the unchanged component (behavioral contrast). This result casts doubt on accounts that attribute behavioral contrast to variations in the rate of noninstrumental elicited respon

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-179

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Ten rats received all of their water in daily 1‐hr sessions. Following a baseline phase in which lever and water spout were freely available throughout each session, subjects were trained to press the lever for water on mixed schedules composed of two alternating components. Each component gave access to water for a fixed cumulation of drinking time every time the rat cumulated a fixed amount of lever‐pressing time. Changes in one component produced contrast and induction effects, both positive and negative, with respect to both lever pressing and drinking in the unchanged component. All schedules facilitated lever pressing relative to baseline. All schedules suppressed drinking relative to baseline, even though contingency sessions allowed ample time to perform the baseline amount of drinking. The entire pattern of results was predicted in quantitative detail by assuming that the total amount of a dimension apportioned to lever pressing and drinking is conserved between baseline and contingency sessions. Conservation theory was shown to predict several effects produced by simple fixed‐ratio schedules, and was compared favorably with probability‐differential (Premack, 1971) and response‐deprivation (Timberlake and Allison, 197

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-185

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Five pigeons were given single‐stimulus training on an 8‐sec differential‐reinforcement‐of‐low‐rate schedule followed by steady‐state generalization training using 12 wavelength stimuli. Three birds had a high percentage of reinforced responses on the training schedule and flat generalization gradients of total responses. The birds with fewer reinforced responses had much steeper generalization gradients. Generalization gradients plotted as a function of both stimulus wavelength and interresponse time showed that for most birds, stimulus control was restricted to responses with long interresponse times. Responses with very short interresponse times were not under stimulus control and there was some evidence of inhibitory control of short interresponse times. Interresponse‐times‐per‐opportunity functions, plotted as a function of stimulus wavelength, showed that stimulus wavelength controlled the temporal distribution of responses, rather than the overall rate of response. The data indicate that the differential‐reinforcement‐of‐low‐rate schedule generates several response categories that are controlled in different ways by wavelength and time‐correlated stimuli, and that averaging responses regardless of interresponse‐ti

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-199

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Four pigeons in the line‐positive group were trained with a vertical line on a green background that signalled intermittent reinforcement while a plain green field signalled extinction. Four pigeons in the line‐negative group were trained with the opposite discrimination. Response to a control key terminated any trial and initiated the next trial. The birds also used the control key during generalization tests to control the durations of trials in which various line orientations were presented. These durations were summed to provide generalization gradients of stimulus duration that were positive or negative in accordance with the trained discriminations. In Experiment 2, birds from the line‐positive group were tested with a procedure in which the control key was not available on some trials. This provided an independent assessment of response rates to the test stimuli. These rates were used to predict the stimulus durations obtained when the control key was available. The findings supported a general model for the prediction of response distributions among concurrent stimuli from rates observed with single st

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-209

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-218

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Four crows were trained to key peck for food. Then, they were exposed to a positive response contingency that required them to peck the key when it was illuminated briefly (the trial) in order to receive food. This procedure resulted in consistent within‐trial pecking. When the contingency changed so that food was presented at the end of a trial when no response occurred, but the trial terminated immediately and food was omitted when a response occurred (negative response contingency), responding decreased markedly. Eight pigeons were studied under the same change in contingencies. These birds varied in their response histories from naive to having several years' experience. The previously naive pigeons also showed rapid declines in responding under the negative contingency; the responding of the birds with extended training histories declined much more slowly. Eventually, however, six of the eight pigeons showed little or no responding under the negative contingency, while they responded consistently when re‐exposed to the positive contingency. These findings question the power and the generality of the negative auto‐maintenance pheno

ISSN:0022-5002    

DOI:10.1901/jeab.1976.25-219

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY