The Use Of Intermittently Reinforcedtechnic In Medical Science

The ability to sustain behavior in animals and people continuously over long periods of time, and with moment-to-moment predictability, provides a technic which is finding increased application in fields of medical science where problems related to behavior arise. The determination of the effect of a chemical compound, a physiologic factor, or psychologic procedure depends upon the availability of a behavioral baseline which can serve as a dependent variable. Intermittently reinforced behavior is providing such a baseline. The following experiments are presented to illustrate applications of behavioral procedures using an intermittently reinforced baseline performance.

Many experiments have shown the role of the hypothalamus and inherited characteristics on obesity. An experiment by Anliker and Mayer (1956) made possible more objective and more detailed descriptions of the eating patterns than was possible by simply recording amount of food eaten and body weight. The description of eating patterns of mice which are obese as the result of various pathologic conditions was made possible by the study of the mice's eating behavior maintained as a baseline performance by a fixed-ratio schedule of reinforcement. Figure 8 shows the behavioral pattern for normal mice and mice which are obese because of gold thioglucose injections, hereditary obesity, and hypothalamic lesions. The objective and systematic method of recording the behavior makes it possible to distinguish and characterize the eating pattern as well as experimental variables which may alter the underlying physiologic condition.

Fig. 8. Behavioral records taken from mice, showing the differential eating patterns, depending upon the etiology of the obesity.

Psychologic Effects Of Electro-Convulsive Shock

The effect of a preaversive stimulus in disrupting the performance of an animal pressing a lever and reinforced on an intermittent schedule of reinforcement provides a technic for experimentally producing a disruption in behavior which has obvious validity for problems in emotion and anxiety. The following experiment on the ameliorating effects of electro-convulsive shock illustrates the use of this objective baseline in evaluating physiologic procedures. Figure 9 illustrates the details of the technic (Hunt and Brady, 1951). The clicker introduced at C completely disrupts the behavior of the rat working for water. As soon as the shock is delivered at S, the animal returns to work. The control performance provides a baseline by which it now becomes possible to evaluate the ameliorative effects of various physiologic procedures on the disruption (anxiety) produced by the clicker. Figure 10 illustrates the effect of 21 electroconvulsive shock treatments, virtually eliminating the aversive effect of the clicker (preaversive stimulus). Baseline procedures of a similar sort have been widely used to evaluate the effect of CNS drugs, particularly tranquilizers, on the emotional effects of similar preaversive stimuli. Such objectives and quantitative methods for analyzing emotional changes in the behavior make it possible to investigate in detail methods for dealing with emotional disruption.

THE USE OF AN INTERMITTENTLY REINFORCED PERFORMANCE TO EVALUATE THE EFFECTS OF PSYCHOLOGIC VARIABLES The effects of hypnosis were studied by the use of an intermittently reinforced baseline in a manner similar to the one used to determine the emotional effect of a pre-shock stimulus described above. The first part of the record in Figure 11 shows the control performance of a human subject pressing keys in a complex performance, reinforced on a variable interval schedule by money. The subject was then hypnotized and during the remainder of the experimental session various suggestions were made to the hypnotized subject. The nature of the suggestions are indicated on the record. The effect of the suggestions can be measured quantitatively by the changes in the rate and accuracy with which the subject emits the intermittently reinforced operant response.

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