Temporal Control in Fixed‐interval Schedules

Abstract

The peak procedure was used to study temporal control in pigeons exposed to seven fixed-interval schedules ranging from 7.5 to 480 s. The focus was on behavior in individual intervals. Quantitative properties of temporal control depended on whether the aspect of behavior considered was initial pause duration, the point of maximum acceleration in responding, the point of maximum deceleration, the point at which responding stopped, or several different statistical derivations of a point of maximum responding. Each aspect produced different conclusions about the nature of temporal control, and none conformed to what was known previously about the way ongoing responding was controlled by time under conditions of differential reinforcement. Existing theory does not explain why Weber's law so rarely fit the results or why each type of behavior seemed unique. These data fit with others suggesting that principles of temporal control may depend on the role played by the particular aspect of behavior in particular situations.Key words: peak procedure, timing, fixed-interval schedules, key peck, pigeonsThe peak procedure was devised by Catania (1970) to study temporal control under fixedinterval (FI) schedules. In an FI schedule, food delivery follows the first response emitted after a specified (and constant) time period has elapsed. If response rate is based on stimulus generalization along the dimension of elapsed time, the point of highest rate presumably reflects when the animal estimates that food is available. By adding empty trials with food omitted and trial length extended well beyond the end of the interval, the peak procedure makes it possible to determine where responding is maximal.Catania (1970) and others (e.g., Maricq, Roberts, & Church, 1981;Meck, Komeily-Zadeh, & Church, 1984;Roberts, 1981Roberts, ,1982Roberts & Holder, 1984) found that the point of peak rate rarely departed by more than 10% from the Fl value, thereby suggesting highly accurate temporal control by the time of food availability. In all of these experiments, peak time was calculated from data cumulated over numerous empty trials. However, the contemporary view (Gibbon & Church, 1990 temporally controlled starting and stopping times over numerous empty trials. The result of this averaging is to generate smooth response-rate curves with well-defined peaks that do not correspond to the long periods of steady response rate without any peak that actually occur in individual trials. This should not be surprising in light of earlier observations about temporal patterning in FI schedules. Evaluations of patterning based on data grouped over multiple intervals typically have been misleading about the nature of behavior as it occurs in individual intervals. Branch and Gollub (1974) showed that the averaged data need not correspond with behavior occurring in any individual interval.The peak procedure can show the sensitivity of animals to time both before and after the fixed interval has elapsed, because it involves interpolated trials uninterrupte...

Does satiation close the open economy?

“…Data show that the point of inflection in FI scallops (the breakpoint; Hanson & Killeen, 1981;Schneider, 1969) is proportional to FI value. Time to the first peck is also sometimes a linear function of the interreinforcer interval (Zeiler & Powell, 1994), but sometimes, it is a power function of the interreinforcer interval (Hanson & Killeen, 1981;Lowe, Harzem, & Spencer, 1979). The lines through the pause durations in Figure 1 are linear functions of the FI value, consistent with the linear waiting time model (Higa, Moreno, & Sparkman, 2002;Staddon, Chelaru, & Higa, 2002;Wynne, Staddon, & Delius, 1996):…”

Human sensitivity to reinforcement in operant choice: How much do consequences matter?

“…Second, many instances ofresponse patterns are the result of indirect variables operating under a reinforcement schedule and are not directly specified by the reinforcement. For example, the fixed-interval "scallop" is not specified in the schedule contingency but instead arises after much contact with the schedule and results from such subtleties as the selective reinforcement of moderate interresponse times and temporal discrimination in nonverbal subjects (see Zeiler, 1994, for an extended discussion).…”

Operant Conditioning

“…But Weber's law and proportional timing are dissociable-it is possible to have proportional timing without conforming to Weber's law and vice versa (cf. Hanson & Killeen 1981, Zeiler & Powell 1994, and in any case both are only approximately true. Timescale invariance therefore does not qualify as a principle in its own right.…”

“…A second dataset that does not agree with timescale invariance is an extensive set of studies on the peak procedure by Zeiler & Powell (1994;see also Hanson & Killeen 1981), who looked explicitly at the effect of interval duration on various measures of interval timing. They conclude, "Quantitative properties of temporal control depended on whether the aspect of behavior considered was initial pause duration, the point of maximum acceleration in responding [break point], the point of maximum deceleration, the point at which responding stopped, or several different statistical derivations of a point of maximum responding … .…”