THE EFFECT OF SMALL SEQUENTIAL CHANGES IN FIXED‐RATIO SIZE UPON THE POST‐REINFORCEMENT PAUSE¹

Abstract

Duration of the post-reinforcement pause was measured for three pigeons on fixed-ratio schedules of reinforcement ranging from 10 to 160. Small sequential changes were made in the ratio values without disrupting stable performance. The post-reinforcement pause increased consistently for all birds within three sessions as the ratio requirement increased. A frequency analysis of the individual pauses at selected fixed ratios revealed an increase in dispersion for all animals as the ratio size increased. Response rate tended to decrease for two of the birds and remained relatively stable for the third; but there were many reversals in these data.The data of Ferster and Skinner (1957) suggest that the post-reinforcement pause increases as the size of the fixed-ratio schedule of reinforcement (FR) is increased. A number of other studies (Kaplan, 1956;Premack, Schaeffer, and Hundt, 1964; Thompson, 1964;Winograd, 1965;Mintz, Mourer, and Gofseyeff, 1967;Felton and Lyon, 1966) METHOD SubjectsThree White Carneaux pigeons were maintained within 10 g of 80% of their free-feeding weight. One (P42) was experimentally naive, the other two (P33, P44) had previous FR training. Water and grit were available at all times in the home cages. ApparatusA Lehigh Valley pigeon test chamber Model 1519C was employed. A grain mixture of 50% kafir, 40% vetch, and 10% hemp was used for reinforcement. A reinforcement time, which ranged from 2 to 3 sec, was empirically determined for each subject so that the animal's weight was maintained within the prescribed limits. During reinforcement the white key light was turned off.The fixed-ratio reinforcement schedule was programmed by a Grason-Stadler ratio counter. The elapsed time from the end of the reinforcement period to the first response in the ratio run, i.e., the post-reinforcement pause, was measured in fourths of a second. This was done by recording the pulses (4 pps) from a Foringer electronic timer which were initiated by the end of the grain hopper cycle and terminated by the animal's first response. These pulses were recorded cumulatively over each daily session on a digital counter; the 89 1968, 11,[589][590][591][592][593] NUMBER 5 (SEPTEMBER)

Temporal control in chained fixed-ratio, fixed-interval schedules.

“…Pauses in the FR schedule in these two previous studies increased with slight increases in the FR schedule. Post-reinforcement pauses showed larger increases than expected based on similar FR data (e.g., Powell, 1968;Crossman, Trapp, Bonem, & Bonem, 1985). The present and previous results (Todorov & Teixeira-Sobrinho, 2009;Todorov et al, 2012) may suggest that pausing in the FR schedule in chained FR FI schedules may tend to increase as the IRI duration increases.…”

Operant Conditioning

“…Thus, the optimal strategy on FR, as on fixed-T RID, is to respond immediately after food. However, in both cases animals wait before responding and, as one might expect based on the assumption of a roughly constant interresponse time on all ratio schedules, the duration of the wait on FR is proportional to the ratio requirement (Powell 1968), although longer than on a comparable chain-type schedule with the same interreinforcement time (Crossman et al 1974). The phenomenon of ratio strain-the appearance of long pauses and even extinction on high ratio schedules (Ferster & Skinner 1957)-may also have something to do with obligatory linear waiting.…”

“…The most obvious application is to ratio schedules. The time to emit a fixed number of responses is approximately constant; hence the delay to food after the first response in each interval is also approximately constant on fixed ratio (FR), as on fixed-T RID (Powell 1968). Thus, the optimal strategy on FR, as on fixed-T RID, is to respond immediately after food.…”

Rats don’t always respond faster for more food: The paradoxical incentive effect

“…Equation 3 provides a good account of the behavior of pigeons on ratio schedules, both on VR schedules with the coupling coefficient defined by Equation 2 (e.g., Green, Kagel, & Battalio, 1982;Mazur, 1983), and on fixed-ratio (FR) schedules (e.g., Powell, 1968) using the appropriate coupling coefficient. In particular, changes in the amount or quality of the reinforcer have the expected effects on both the shape of the response rate functions and on the corresponding values of a (see Figure 2, from Bizo & Killeen, 1997).…”