Adjusting Fixed‐ratio Schedules in the Squirrel Monkey

112

Thirteen pigeons were exposed to a variety of second-order schedules in which responding under a component schedule was reinforced according to a schedule of reinforcement. Under different conditions, completion of each component resulted in either (1) the brief presentation of a stimulus also present during reinforcement (pairing operation), (2) the brief presentation of a stimulus not present during reinforcement (nonpairing operation), or (3) no brief stimulus presentation (tandem). Brief-stimulus presentations engendered a pattern of responding within components similar to that engendered by food. Patterning was observed when fixed-interval and fixed-ratio components were maintained under fixed-and variable-ratio and fixed-and variable-interval schedules. There were no apparent differences in performance under pairing and nonpairing conditions in any study. The properties of the stimuli presented in brief-stimulus operations produced different effects on response patterning. In one study, similar effects on performance were found whether brief-stimulus presentations were response-produced or delivered independently of responding. Response patterning did not occur when the component schedule under which a nonpaired stimulus was produced occurred independently of the food schedule. The results suggest a reevaluation of the role of conditioned reinforcement in second-order schedule performance. The similarity of behavior under pairing and nonpairing operations is consistent with two hypotheses: (1) the major effect is due to the discriminative properties of the brief stimulus; (2) the scheduling operation under which the paired or nonpaired stimulus is presented can establish it as a reinforcer.

Section: Resultssupporting

confidence: 85%

Section: Introduction General Methods Part Imentioning

confidence: 99%

Second‐order Schedules and the Problem of Conditioned Reinforcement

Stubbs

1971

112

“…Byrd and Marr (1969), de Lorge (1967), Kelleher (1966), Staddon (1972), Staddon and Innis (1969), Stubbs (1969), and the present Experiment I used stimuli ranging from 0.5 sec to 4 sec in duration and failed to obtain the same behavior as when intervals ended with food presentation. Stubbs (1971) Kelleher, Fry, and Cook (1964) and Zeiler (1970) followed some ratios with a brief stimulus that was never correlated with food, responding did not differ noticeably depending on whether a ratio ended with these events or with food. Since, in addition, Neuringer and Chung observed identical behavior when they substituted a fixed-ratio for the fixedinterval schedule, it does seem possible that their findings characterize fixed-ratio-like performance.…”

Section: Discussionmentioning

confidence: 88%

FIXED‐INTERVAL BEHAVIOR: EFFECTS OF PERCENTAGE REINFORCEMENT¹

Zeiler

1972

The percentage of fixed intervals terminating with food presentation was varied parametrically. Intervals that did not end with food were terminated by a stimulus uncorrelated with food presentation (a timeout stimulus). In Experiment I, the pigeons' response rates were an inverted U-shaped function of the percentage of food presentations: decreasing the percentage from 100% to 90%, 70%, or 50%0 produced an increase in response rates; lower percentages decreased the rates. The patterns of responding in the 100% condition differed from those of the other conditions. In Experiment II, the chamber was darkened after food presentations and timeouts. Response rate was directly related to the percentage of food presentations: decreasing the percentage decreased the response rate.Characteristic fixed-interval patterns of responding were maintained as long as there were occasional food presentations; pausing followed by positively-accelerated responding occurred in percentage conditions ranging from 7% to 100%. The ability to maintain fixed-interval performance with percentage reinforcement suggested that the behavioral sequences occurring in each interval may operate as unitary responses.A simple fixed-interval (FI) schedule specifies that reinforcement follows the first response occurring a constant time period after the preceding reinforcement. It is also possible to reinforce fixed-interval behavior intermittently instead of every time an interval is completed. In a second-order schedule involving fixed-interval components, only occasionally does the completion of a fixed interval terminate in food presentation. For example, Kelleher (1966) presented food after every thirtieth fixed interval; this is a second-order schedule having fixed-interval components reinforced according to a fixed-ratio (FR 30) schedule.A consistent finding with second-order schedules has been that if each fixed interval ends with a brief stimulus paired with food presentation, responding is similar to that occurring when food follows every interval (Byrd and Marr, 1969;de Lorge, 1967;Kelleher, 1966;Marr, 1969;Stubbs, 1969). Namely, a pause at the outset of each interval is followed by a positively accelerated rate of responding. If, however, the brief stimulus is not paired ' (1969) found that pigeons paused after food presentation but did not do so after the presentation of a brief nonpaired stimulus. Neuringer and Chung (1967) and Stubbs (1971), however, found that a stimulus did not have to be paired with food presentation to maintain pausing and positive acceleration. A stimulus uncorrelated with food presentation had effects identical to that of food in controlling the rate and pattern of responding.The discrepancy between Neuringer and Chung's and Stubbs' and the other data indicates the importance of obtaining further information about the effects of stimuli not paired with food presentation. The present experiments studied such a procedure by varying the relative number of fixed intervals ending with food and with a stimulus not p...

“…But the generality extends to another response class as well. Findley (1962) and Kelleher, Fry, and Cook (1964) showed that differential reinforcement of the duration of the pause before the first response emitted on fixed-ratio schedules operated in the same way. Differential reinforcement of a property appears to control whatever response is specified independent of the size of the response or whether it involves emitting or withholding a specified response.…”

Section: -20pmentioning

confidence: 93%

TIME LIMITS FOR COMPLETING FIXED RATIOS. II. STIMULUS SPECIFICITY¹

Zeiler

1972

Pigeons were exposed to two stimuli that were each correlated with the same fixed-ratio schedule. During one stimulus, the ratio had to be completed in more than a specified time for food to be presented. During the other, the ratio had to be completed in less than a specified tinme. Failures to meet the time criterion produced a timeout and reset the ratio.Treating the entire behavioral sequence generated by a fixed-ratio schedule as a unitary response and scheduling differential reinforcement with respect to the duration of the sequence produced effects comparable to those observed previously with individual responses. The times taken to complete the ratios conformed to the time criteria under both stimulus conditions. Similar effects have been observed with differential reinforcement of the duration of individual responses and in experiments specifying running speed criteria under discrete trial conditions.Evidence has begun to accumulate indicating that entire sequences of behavior resemble individual responses in the way they are affected by reinforcement. Kelleher (1966) The present experiment continued the analysis of how behavioral sequences generated by fixed-ratio schedules are affected when they are treated as unitary responses. Notterman and Mintz (1962) reported that if a response of a certain force was required in the presence of one stimulus, while a response of a different force was required in the presence of another stimulus, the forces emitted differed appropriately during the two stimuli. The present experiment studied whether the duration of fixed-ratio sequences would be brought under stimulus control by correlating two stimuli with identical fixed-ratio schedules but with different duration requirements. The conformity of durations to the specific requirements would mean that a property of the sequence was brought under stimulus control, and would be further evidence for the similarity of sequences and individual responses. METHOD SubjectsThree White Carneaux pigeons were maintained at 80% of their free-feeding weights. Bird 71 had experience with simultaneous discriminations involving differential reinforcement under fixed-interval schedules, Bird 16 had an extensive history with a variety of schedules, the most recent being a fixed-interval schedule, and Bird 56 had been exposed to fixed-ratio schedules with time criteria. 243 1972, 18,[243][244][245][246][247][248][249][250][251] NUMBER 2 (SEPTEMBER)