Within-session changes in responding when rate and duration of reinforcement vary

Animal Learning & Behavior

2001

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Two experiments tested the hypothesis that habituation contributes to within-session decreases in responding. In Experiment 1, rats' leverpressing was reinforced under a fixed ratio (FR) 4 schedule throughout the baseline sessions. During the dishabituation sessions, the first 21 min and the last 21 min were FR 4; dishabituating events occurred during the middle 3 min. The dishabituating events altered the manner of reinforcer delivery in four different ways. Response rates increased after all dishabituating events. In Experiment 2, rats responded on several FR and variable ratio (VR) schedules. The ratio requirement varied from 3 to 15. Within-session decreasesin responding were steeper during FR schedules than during VR schedules. In addition, response rates were well described as linear functions of cumulative number of food pellets eaten within sessions. These results support the habituation hypothesis but do not rule out the possibility that other satiety variables might contribute simultaneously.

Section: Discussionmentioning

confidence: 63%

Habituation may contribute to within-session decreases in responding under high-rate schedules of reinforcement

Aoyama

Animal Learning & Behavior

2001

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“…For example, the average rate of responding was faster when subjects responded at 75% than at 85% or 95% of their free-feeding weights. Therefore, it is unlikely that the experimental manipulations failed to alter the subjects' level of satiation (see also Cannon & McSweeney, 1995;McSweeney & Johnson, 1994;Weatherly, McSweeney, & Swindell, 1995). Figure I may provide additional support for sensitization-habituation as an explanation for within-session changes in operant responding.…”

Section: Discussionmentioning

confidence: 90%

Reinforcer value may change within experimental sessions

Psychonomic Bulletin & Review

Weatherly

Swindell

1996

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Large and systematic changes in response rates often occur within sessions during operant conditioning procedures. In the present experiment, we asked whether the value of the reinforcer that supports responding also changes within sessions, Pigeons pecked a key for mixed grain available throughout the session. Occasionally, wheat was also provided for pecking a second key. The ratio of the rates of responding for mixed grain and wheat, a frequently used measure of relative reinforcer value, changed significantly within sessions when mixed grain was provided at high, but not at low, rates. Habituation to the reinforcer provides the most likely explanation for these changes in reinforcer value. Eventually, habituation may provide a unified explanation for the within-session changes in behavior that occur when many species of subjects respond on a wide variety of tasks.Large and systematic changes in response rates occur within sessions when subjects respond on operant conditioning procedures (see, e.g., McSweeney, 1992). Although these changes have been recognized for many years, they have been treated as problems to be controlled by giving warm-up trials (e.g., Hodos & Bonbright, 1972) or time to adapt to the apparatus (e.g., Papini & Overmier, 1985), rather than as phenomena to be studied. However, further consideration suggests that within-session changes deserve study in their own right. These changes may be large and reliable (e.g., McSweeney & Hinson, 1992). They occur for many species of subjects performing a variety of responses on many different procedures (McSweeney & Roll, 1993). They may also have a number of methodological and theoretical implications (McSweeney & Roll, 1993). For example, within-session changes challenge both molar (e.g., Herrnstein, 1970) and molecular (e.g., Hinson & Staddon, 1983) theories. Molar theories are challenged because within-session changes imply that the primary variable used by these theories, rate of responding averaged over the session, masks regularities in behavior at a more molecular level. Molecular theories are challenged because these theories must account for withinsession changes if they are to reach their goal of describing behavior on a moment-by-moment basis.In the present experiment, we asked whether changes in the effectiveness or the value of the reinforcer produce the within-session changes in response rates. Several authors have argued that the relative value of two reinforcers is indicated by the ratio of the rates of respond-EK.M., IN.W., and S.S. thank Cari B. Cannon for her comments on an earlier version of this manuscript. This material is based on work supported by the NSF (IBN-9403719). The treatment of the subjects was in accordance with institutional guidelines. Correspondence should be addressed to E K. McSweeney, Department of Psychology, Washington State University, Pullman, WA 99164-4820 (e-mail: fkmcs@mail.wsu.edu).ing for those reinforcers during concurrent schedules (e.g., Baum, 1974). Miller (1976) provided support for this measure. ...

“…Several variables that should alter satiation do not alter the within-session patterns. For example, Roll , McSweeney, Johnson, and Weatherly (1995) varied the deprivation level of rats responding for food from 75 to 95% of free-feeding body weight and varied the caloric density of the reinforcer from 0 to 15.2 calories per gram without altering the within-session pattern of responding (see also Cannon & McSweeney, 1995;McSweeney & Johnson, 1994;McSweeney & Roll, 1997;; but see also Bizo, Bogdanov, & Killeen, 1998;Palya & Walter, 1997).…”

Section: Within-session Patterns Of Respondingmentioning

confidence: 99%

“…When operant responding is maintained by food, increasing the magnitude of the reinforcer (food) decreases response rate averaged over the session , but it does not influence the within-session pattern of responding until very large magnitude reinforcers are used (Cannon & McSweeney, 1995;Roll et aI., 1995). For instance, Roll et al demonstrated that changing the magnitude of reinforcement by a factor of 3 did not alter the with in-session response pattern when responding by rats was maintained with condensed milk but did substantially decrease the rate of responding .…”

Section: Influence Of Other Variablesmentioning

confidence: 99%

Within-Session Changes in Response Rate: Implications for Behavioral Pharmacology

1999

Psychol Rec

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An assumption inherent in the theory and practice of operant psychology is that response rate is relatively invariant during steadystate procedures. Recent research has refuted this assumption, demonstrating instead that response rate changes in a large and systematic fashion during many steady-state operant procedures. This finding mandates that operant researchers take into account these within-session changes in response rate when designing and conducting research . Because behavioral pharmacologists use operant techniques and principles, these within-session changes in response rate must be taken into account when conducting behavioral pharmacological research as well. This paper briefly reviews what is known about within-session response patterns and poses the question: Might similar factors contribute to within-session changes in response rate when both drug and nondrug reinforcers are used? Finally, the paper explores some implications of within-session changes in response rate for behavioral pharmacology.Behavioral pharmacology is an eclectic field in which practitioners make use of techniques from several traditional areas of psychology. One area to which behavioral pharmacology owes a particularly strong allegiance is the experimental analysis of behavior (i.e., operant psychology) (Higgins, Bickel, & Hughes, 1993;Thompson & Schuster, 1968). Both basic and applied researchers in behavioral pharmacology make use of techniques and principles which were originally developed by researchers and practitioners of operant psychology. For example, clinical behavioral pharmacologists frequently employ contingency-management strategies to promote abstinence in substance abusers (Bigelow, Stitzer, & Liebson, 1984). Behavioral pharmacologists engaged in basic research often employ preparations in which an organism self-administers a drug