Periodic Response-Reinforcer Contiguity: Temporal Control but Not as We Know It!
Keenan, Michael, The Psychological Record
When significant events in the environment occur on a regular basis, people adapt by producing regularities in their behavior. Some of these events may be separated in time by a year or more (e.g., anniversaries) and others occur on a smaller time scale (e.g., weekends off work, lunch breaks during the day, etc.). In the laboratory, simulations of periodicity in behavior have been studied with both humans and nonhumans. The general approach has been to arrange a contingency between a selected behavior and an environmental event to ensure that the environmental event occurs at regular intervals. The technical term for this arrangement is a 'schedule of reinforcement.' A wide variety of schedules of reinforcement have been studied in the laboratory and each is associated with a distinctive pattern of behavior (Catania, 1998).
One of the most studied laboratory procedures for investigating periodicity in behavior is the fixed-interval (FI) schedule of reinforcement. Reinforcer delivery on this schedule is dependent upon the occurrence of a single response after a fixed period of time has elapsed since the previous reinforcer presentation. Baseline performance on this schedule is typically described as involving a postreinforcement pause (PRP) followed by either an accelerating or a constant response rate up to the next reinforcer delivery (Baron & Leinenweber, 1994; Cumming & Schoenfeld, 1958; Dews, 1970; Ferster & Skinner, 1957; see Hyten & Madden, 1993, for a discussion of problems arising from imprecision in the description of human FI performance). In the analysis of this performance a variety of techniques of have been employed. These can be grouped together according to whether they involved simple parametric investigations of the interreinforcer interval, manipulation of the single response contingency, disruption of responding during the interreinforcer interval by the presentation of other stimuli, or the replacement of occasional reinforcer presentations by other stimuli (for extended discussions of these and other related procedures see Davey, 1987; Keenan, 1986; Lowe & Wearden, 1981; Richelle & Lejeune, 1980; Staddon, 1983; Zeiler, 1977).
The analysis of patterns of behavior on schedules generally has proven difficult because even on the simplest of schedules it is recognized that behavior is multiply determined (Morse & Kelleher, 1997; Zeiler, 1997). Thus, although the formal description of a schedule may reference simply the programmed relation between the behavior and the environmental event, closer inspection shows that other variables operate collectively to produce baseline responding. For example, Keenan and Leslie (1986) (see also Keenan & Toal, 1991) offered a structural analysis of the independent variables that collectively define a FI schedule. They pointed out that there were four variables acting in concert: (a) the time between reinforcer presentations; (b) the single response contingency; (c) response-reinforcer contiguity; and (d) the time from one reinforcer presentation to the location in time of the next response dependency. The inspiration for this work came from the effects observed on another schedule that is similar in makeup to a FI schedule, a recycling conjunctive fixed-time (FT) fixed-ratio (FR) 1 schedule.
A FI schedule can be seen as a tandem FT FR 1 schedule of reinforcement. Thus, once the FT component expires, and only then, a FR 1 contingency comes into operation. A major effect of this particular construction is that it ensures periodic occurrences of response-reinforcer contiguity. A recycling conjunctive FT FR 1 schedule is similar to a FI schedule in that it too has a single response contingency and it also presents reinforcement at regular intervals. However, unlike the FI schedule a single response executed any time during a FT component results in reinforcer delivery at the end of that FT component. Also, if a response fails to occur during a FT component, that component ends without any stimulus event and the next FT component begins immediately. …