Alan Baron

Analyzing the Reinforcement Process at the Human Level: Can Application and Behavioristic Interpretation Replace Laboratory Research?

Critics have questioned the value of human operant conditioning experiments in the study of fundamental processes of reinforcement. Contradictory results from human and animal experiments have been attributed to the complex social and verbal history of the human subject. On these grounds, it has been contended that procedures that mimic those conventionally used with animal subjects represent a “poor analytic preparation” for the explication of reinforcement principles. In defending the use of conventional operant methods for human research, we make three points: (a) Historical variables play a critical role in research on processes of reinforcement, regardless of whether the subjects are humans or animals. (b) Techniques are available for detecting, analyzing, and counteracting such historical and extra-experimental influences; these include long-term observations, steady state designs, and, when variables are not amenable to direct control (e.g., age, gender, species), selection of subjects with common characteristics. (c) Other forms of evidence that might be used to validate conditioning principles—applied behavior analysis and behavioristic interpretation—have inherent limitations and cannot substitute for experimental analysis. We conclude that human operant conditioning experiments are essential for the analysis of the reinforcement process at the human level, but caution that their value depends on the extent to which the traditional methods of the experimental analysis of behavior are properly applied.

Positive and Negative Reinforcement: Should the Distinction Be Preserved?.

Michael (1975) reviewed efforts to classify reinforcing events in terms of whether stimuli are added (positive reinforcement) or removed (negative reinforcement). He concluded that distinctions in these terms are confusing and ambiguous. Of necessity, adding a stimulus requires its previous absence and removing a stimulus its previous presence. Moreover, there is no good basis, either behavioral or physiological, that indicates the involvement of distinctly different processes, and on these grounds he proposed that the distinction be abandoned. Despite the cogency of Michael’s analysis, the distinction between positive and negative reinforcement is still being taught. In this paper, we reconsider the issue from the perspective of 30 years. However, we could not find new evidence in contemporary research and theory that allows reliable classification of an event as a positive rather than a negative reinforcer. We conclude by reiterating Michael’s admonitions about the conceptual confusion created by such a distinction.

The place of the human subject in the operant laboratory.

Although laboratory study of human behavior seems an obvious vehicle for strengthening the scientific base of behavior analysis, the place of the human subject within the operant laboratory remains problematic. The prevailing research strategy has been to link principles developed with animals to human affairs, either through interpretation of naturally occurring human behaviors or through application of the principles to the solution of human problems. The paucity of laboratory research on human operant behavior derives from several misconceptions: the possibility that experimental demand characteristics and pre-experimental behavioral dispositions of human subjects contaminate the results; that ethical considerations place undue constraint on research topics and experimental designs; and that uncontrollable variation in subjects’ histories and other relevant personal characteristics prevents observation of reliable functional relations. We argue that these problems do not pose insurmountable obstacles to the experimental analysis of human behavior; that adequate methods of control and analysis are available; and that operant techniques, by emphasizing experimentally imposed contingencies, are well suited for the laboratory study of human behavior.

What 50 Years of Research Tell Us About Pausing Under Ratio Schedules of Reinforcement

Textbooks in learning and behavior commonly describe performance on fixed-ratio schedules as “break and run,” indicating that after reinforcement subjects typically pause and then respond quickly to the next reinforcement. Performance on variable-ratio schedules, on the other hand, is described as steady and fast, with few long pauses. Beginning with Ferster and Skinner’s magnum opus, Schedules of Reinforcement (1957), the literature on pausing under ratio schedules has identified the influences on pausing of numerous important variables, in particular ratio size and reinforcement magnitude. As a result, some previously held assumptions have been called into question. For example, research has shown that the length of the pause is controlled not only by the preceding ratio, as Ferster and Skinner and others had assumed (and as implied by the phrase postreinforcement pause), but by the upcoming ratio as well. Similarly, despite the commonly held belief that ratio pausing is unique to the fixed-ratio schedule, there is evidence that pausing also occurs under variable-ratio schedules. If such widely held beliefs are incorrect, then what about other assumptions? This article selectively examines the literature on pausing under ratio schedules over the past 50 years and concludes that although there may indeed be some common patterns, there are also inconsistencies that await future resolution. Several accounts of pausing under ratio schedules are discussed along with the implications of the literature for human performances, most notably the behaviors termed procrastination.

Experimental Design and Analysis in the Laboratory Study of Human Operant Behavior

Research methods play an essential role in efforts to describe, understand, and control nature. Consensus about appropriate procedures and practices allows researchers to compare and integrate their observations with those of others. On a deeper level, a researcher’s methods express what is regarded as important in the field under study—and what is not. Consider, for example, the earliest experiments of psychologists in which subjects were asked to report on the contents of their consciousness as they engaged in various activities (Boring, 1950, Chapter 16). This “method of introspection” reflected the conviction that the important questions of psychology pertained to the individual’s mental life. Behavior was of interest, but only insofar as it shed light on consciousness and the like. Later psychologists led by Watson and Skinner came to regard behavior as interesting and important in its own right. This emphasis is reflected in the label attached to the methods originated in Skinner’s seminal work on operant conditioning in rats (Skinner, 1938) and pigeons (Ferster & Skinner 1957): the experimental analysis of behavior.

Immediate and delayed punishment of human behavior by loss of reinforcement

Abstract Young adult humans pressed a key to obtain money. When responding was punished by presentation of a stimulus signifying that money was lost, response frequencies decreased and response latencies increased. Since these changes did not increase relative earnings, the aversive properties of loss of reinforcement were manifested independently or reinforcement gain. When loss punishment was delayed for either 10, 20, or 40 sec the extent of suppression was found to vary inversely with the response-punishment interval. Subsequent manipulations indicated that the effectiveness of delayed punishment was increased when the response also produced immediate conditioned punishment, i.e., a stimulus paired with the delayed loss stimulus. Instructions about the response-punishment contingency had similar effects. The findings were consistent with animal studies of delayed shock punishment, insofar as a similar delay-of-punishment gradient was observed, and with studies of delayed positive reinforcement, insofar as mediation through conditioned punishment (or instructions) increased the effectiveness of delayed punishment.

Human postdiscrimination gradients: The effects of three-stimulus discrimination training

Young adult subjects were trained in a discrimination involving three pure tones varying in pitch, with two positive stimuli and a negative stimulus located midway between the two. Subjects in the control conditions were trained only with the two positive stimuli. Generalization gradients were bimodal in all cases, but for the control subjects, the modes were at the positive stimulus values, while postdiscrimination gradients were displaced away from the negative stimulus toward the extremes of the continuum. Since, with this procedure, the training and test adaptation levels were the same, the observed displacements are difficult to explain in terms of an adaptation-level account of peak shifts. The observed shifts are more consistent with the conditioning-extinction model which assumes interactions between inhibitory and excitatory gradients. However, overall response rates did not reflect the action of summation processes.

Quantitative summaries of single-subject studies: What do group comparisons tell us about individual performances?

Kollins, Newland, and Critchfield (1999) responded to our comments about their review by arguing that their quantitative summary was not a meta-analysis and should not be criticized in these terms. We reply that regardless of what they call their review, it included confounding effects that make interpretations of the results problematic. Kollins et al. also argued that unexpected findings of the sort they reported can serve as a spur for further research. We reply that the understanding of findings that deviate from existing knowledge may well require empirical investigation. Such endeavors, however, should begin with an evaluation of the review procedures that suggested the existence of the differences. Finally, we emphasize that quantitative summaries of individual data are, in the end, a form of group comparison. The implications of using group methods to clarify individual data deserve frank recognition in discussions of the outcomes.Kollins, Newland, and Critchfield (1999) responded to our comments about their review by arguing that their quantitative summary was not a meta-analysis and should not be criticized in these terms. We reply that regardless of what they call their review, it included confounding effects that make interpretations of the results problematic. Kollins et al. also argued that unexpected findings of the sort they reported can serve as a spur for further research. We reply that the understanding of findings that deviate from existing knowledge may well require empirical investigation. Such endeavors, however, should begin with an evaluation of the review procedures that suggested the existence of the differences. Finally, we emphasize that quantitative summaries of individual data are, in the end, a form of group comparison. The implications of using group methods to clarify individual data deserve frank recognition in discussions of the outcomes. We thank Marshall Dermer for his helpful comments.

DIFFERENTIAL EFFECTS OF FEAR ON ACTIVITY IN NOVEL AND FAMILIAR ENVIRONMENTS

The locomotor activity of mice was observed in an open field which was either novel or had been explored for 20 min. Immediately before entry into the open field, groups of Ss were given either 0, 4, or 12 shocks in an adjoining compartment. Ss given either 4 or 12 shocks showed a suppression of activity relative to the performance of nonshocked control Ss, suppression being more marked in the familiar than in the novel environment. Within the novel environment shocked Ss were less active than nonshocked Ss near the shock compartment but slightly more active in far areas. In the familiar environment, by contrast, suppression of activity among shocked Ss was manifested in all areas of the open field. It was concluded that activity by fearful animals is influenced by their familiarity with the environment in which the activity occurs and that this relationship can be understood in terms of the adaptive consequences of such behavior in the history of the animal.

Statistical inference in behavior analysis: Friend or foe?

Behavior analysts are undecided about the proper role to be played by inferential statistics in behavioral research. The traditional view, as expressed in Sidman’s Tactics of Scientific Research (1960), was that inferential statistics has no place within a science that focuses on the steady-state behavior of individual organisms. Despite this admonition, there have been steady inroads of statistical techniques into behavior analysis since then, as evidenced by publications in the Journal of the Experimental Analysis of Behavior. The issues raised by these developments were considered at a panel held at the 24th annual convention of the Association for Behavior Analysis, Orlando, Florida (May, 1998). The proceedings are reported in this and the following articles.