ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-1

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-7

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-10

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Pigeons were studied in two experiments using a delayed matching‐to‐sample task. In Experiment 1, 4 subjects were exposed to a task in which the proportion of reinforcement associated with matching and nonmatching, and the overall proportion of reinforcement associated with selecting each choice, regardless of the sample stimulus, were varied. Choice was sensitive to both proportions. A least squares regression analysis showed that Wixted's (1989) proportions of reinforcement model closely fit the data from Experiment 1; however, the model failed to make accurate qualitative predictions for some test conditions. In Experiment 2, 4 subjects were exposed to a delayed matching‐to‐sample task in which the retention intervals and the reduction in delay to reinforcement signaled by the onset of the sample stimulus were independently varied. When the retention interval was short and when the delay‐reduction value of the sample stimulus was high, the sample exerted greater control over choice; the control by the overall proportion of reinforcements for selecting each choice stimulus was correspondingly low. Conversely, when the retention interval was long and the delay‐reduction value of the sample stimulus was low, the sample exerted relatively less control over choice; control by the overall proportion of reinforcements obtained for selecting each choice stimulus was correspondingly high. A signal detection analysis found that sensitivity to reinforcement varied directly with retention interval. Data were also consistent with misallocation models. No evidence was found to suggest that pigeons ignore the rate at which selecting individual choice stimuli is reinforced, as has been reported in studies with hum

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-11

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Pigeons were exposed to self‐control procedures that involved illumination of light‐emitting diodes (LEDs) as a form of token reinforcement. In a discrete‐trials arrangement, subjects chose between one and three LEDs; each LED was exchangeable for 2‐s access to food during distinct posttrial exchange periods. In Experiment 1, subjects generally preferred the immediate presentation of a single LED over the delayed presentation of three LEDs, but differences in the delay to the exchange period between the two options prevented a clear assessment of the relative influence of LED delay and exchange‐period delay as determinants of choice. In Experiment 2, in which delays to the exchange period from either alternative were equal in most conditions, all subjects preferred the delayed three LEDs more often than in Experiment 1. In Experiment 3, subjects preferred the option that resulted in a greater amount of food more often if the choices also produced LEDs than if they did not. In Experiment 4, preference for the delayed three LEDs was obtained when delays to the exchange period were equal, but reversed in favor of an immediate single LED when the latter choice also resulted in quicker access to exchange periods. The overall pattern of results suggests that (a) delay to the exchange period is a more critical determinant of choice than is delay to token presentation; (b) tokens may function as conditioned reinforcers, although their discriminative properties may be responsible for the self‐control that occurs under token reinforcer arrangements; and (c) previously reported differences in the self‐control choices of humans and pigeons may have resulted at least in part from the procedural conventions of using token reinforcers with human subjects and food reinforcers with pi

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-29

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Four pigeons were exposed to autoshaping procedures in which an 8‐second light on a response key was followed by food. Pecks on the key had no scheduled consequences. Subjects were also exposed to negative automaintenance procedures in which a peck on the illuminated key canceled the following food. The intertrial interval varied from an average of 7 seconds to an average of 232 seconds in different conditions. Rate of responding usually changed within sessions during autoshaping. Responding also changed within sessions for the 1 subject that responded during negative automaintenance. The within‐session patterns of responding were flatter, peaked later, and were more symmetrical around the middle of the sessions at lower rates of food presentation, regardless of whether subjects responded on autoshaping, negative automaintenance, or previously reported variable‐interval schedules. These results imply that similar variables produce within‐session changes in responding during both classical (Pavlovian) and operant conditioning pro

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-51

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

A discrete‐trials adjusting‐delay procedure was used to investigate the conditions under which pigeons might show a preference for partial reinforcement over 100% reinforcement, an effect reported in a number of previous experiments. A peck on a red key always led to a delay with red houselights and then food. In each condition, the duration of the red‐houselight delay was adjusted to estimate an indifference point. In 100% reinforcement conditions, a peck on a green key always led to a delay with green houselights and then food. In partial‐reinforcement conditions, a peck on the green key led either to the green houselights and food or to white houselights and no food. In some phases of the experiment, statistically significant preference for partial reinforcement over 100% reinforcement was found, but this effect was observed in only about half of the pigeons. The effect was largely eliminated when variability in the delay stimulus colors was equated for 50% reinforcement conditions and 100% reinforcement conditions. Idiosyncratic preferences for certain colors or for stimulus variability may be at least partially responsible for the

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-63

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Five rats and 4 pigeons responded for food delivered by several concurrent variable‐interval schedules. The sum of the rates of reinforcement programmed for the two components varied from 15 to 480 reinforcers per hour in different conditions. Rates of responding usually changed within the experimental session in a similar manner for the two components of each concurrent schedule. The within‐session changes were similar to previously reported changes during simple schedules that provided rates of reinforcement equal to the sum of all reinforcers obtained from the concurrent schedules. The number of changeovers also changed within sessions in a manner similar to the changes in instrumental responding. These results suggest that changeovers are governed by the same variables that govern instrumental responding. They also suggest that the within‐session change in responding during each component of a concurrent schedule is determined by approximately the sum of the reinforcers obtained from both components when both components provide the same type of reinf

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-75

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

In two experiments, pigeons were trained with concurrent‐chains schedules, wherein responding to equal initial links measured preference between variable‐interval terminal links. Absolute terminal‐link duration was varied by keeping constant the difference between the terminal‐link delays and forcing their ratio to change. Delay‐reduction theory scales value relative to a common temporal context and requires that delay differences control choice. Thus, preference should remain invariant. Most competing accounts, including the matching law and a strong form of Weber's law, require that preference vary with the delay ratio. Experiment 1 employed standard concurrent chains, in which terminal‐link position and color were confounded. Although average preference remained constant, individual preferences were highly variable and inconsistent, possibly due to carryover of position biases across conditions. In an attempt to reduce variability, Experiment 2 used a modified concurrent‐chains procedure. Preference at different terminal‐link durations was assessed simultaneously to prevent order effects, and terminal‐link position was alternated randomly across trials to minimize the impact of position biases. In Experiment 2, both individual and mean preferences showed the constant‐difference invariance. Overall, choice was controlled by terminal‐link di

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-97

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

According to a diffusion generalization model, time discrimination is determined by the frequency and recency of preceding intervals of time. A procedure for studying rapid timing was used to investigate whether pigeons' wait‐time responses were sensitive to these factors. In Experiment 1 the number (two or eight) and spacing (consecutive or far apart) of 5‐s interfood intervals (called impulses) intercalated in a series of 15‐s interfood intervals (nonimpulses) were studied. Experiment 2 was identical to the first but the interfood intervals were increased by a factor of three. Overall, impulses shortened wait times in the next interfood interval. However, several impulses occurring in succession extended the localized effect of an impulse: Wait times following a set of eight‐close impulses were slow to recover to preimpulse levels. The results show that linear waiting is only an approximation to the dynamic process, and a process that is sensitive to events in an animal's remote past, such as the diffusion generalization model, provides a better account of rapid timing

ISSN:0022-5002    

DOI:10.1901/jeab.1996.66-117

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY