Conditional probability judgments: Effects of imagining vs experiencing the conditioning event

Applications of Bayesian conditionalization often involve two temporal aspects: a probability judgment is based on knowledge at a point in time and is revised over time in light of added information. Let t, t′, and t″ designate three chronological points in time. E designates a target event which occurs or not at t″, and C designates a conditioning event which occurs or not at t′. Suppose that an individual judges P(EC) at t. If C occurs, Bayesian conditionalization requires that a judgment of P(E) at t′ is equal to the earlier judgment of P(EC). However, inconsistencies may result because a judgment of P(EC) at t is based on imagining C, while a judgment of P(E) at t′ is based on experiencing C. This study examines two sources of such inconsistencies. First, C normally is an abstraction of what might happen between t and t′. What actually happens may differ, such that an individual observes extraconditional information which affects a judgment of P(E) at t′. Second, experiencing C may change an individual's affective state, leading to greater optimism or pessimism about the occurrence of E. We report an experiment which documents both effects.     

Apple Picker: Computer software for studying human responding on concurrent and multiple schedules

Apple Picker, a software package for the Apple II microcomputer, is described. Subjects respond by searching for “apples” in two “orchards.” “Attempted pickings” may be reinforced according to random ratio or interval schedules. “Search” responses are recorded and may be examined either as rates of responding in the two orchards or visually as paths the subject has traced during the session.     

Pecking and feeding in chicks

Pecking is not controlled by nutritional state in a newly hatched chick, but by 3 days posthatch it normally is. This paper tests the hypothesis that first a chick must learn that pecking leads to ingestion; then, other (nonlearned) processes are automatically responsible for differential pecking rates to nutritive and nonnutritive items. The first experiment shows that experience pecking and ingesting sawdust is sufficient for differential pecking to develop. The second experiment shows that swallowing without pecking (using a force-feeding technique) does not lead to differential pecking. The third experiment shows that pecking without swallowing (using sand glued down to the floor) also does not lead to differential pecking. Finally, the last experiment shows that food deprivation affects pecking rate only after pecking and ingestion have been associated. These results support the above hypothesis that pecking followed by ingestion leads to the “attachment” of the pecking response to the feeding system. Motivational independence of pecking and the hunger system, the association of pecking with ingestion, and the development of behavior systems are discussed. It is concluded that the function of a behavior may not be related to its causes.     

Desire for control, locus of control, and proneness to depression

Two personality constructs, desire for control and locus of control, were related to depression among college students. Measures of levels of depression, desire for control, and locus of control were taken from subjects. Approximately six months later 71% of these subjects returned a questionnaire concerning their experiences with depression during that six-month period. It was found that locus of control scores, particularly the extent to which subjects perceived that their lives were controlled by chance, were significantly related to the depression levels. It was also found that high desire for control subjects who held external perceptions of control were most likely to seek nonprofessional help for depression. In addition, high desire for control subjects who perceived their lives as generally controlled by chance were most likely to have suicidal thoughts. The results are interpreted in terms of a general style that may promote a proneness to depression for certain individuals.     

Desire for control and reaction to proattitudinal and counterattitudinal arguments

The role of motivation for control in an individual's reaction to persuasive arguments was examined. Subjects scoring either high or low on an individual difference measure of desire for control (DC) were exposed to a position on the Equal Rights Amendment with which they either initially agreed or disagreed. It was found that more often high-DC subjects exposed to a proattitudinal message changed their attitudes in the direction advocated than did low DC subjects. Conversely, more often low-DC subjects exposed to counterattitudinal arguments changed their attitudes in the direction of the advocated position than did high-DC subjects. The findings suggest that a motivation to control events may be operative in some attitude-change situations.     

Operant conditioning permits voluntary,noninvasive measurement of blood pressure in conscious,unrestrained baboons (Papio cynocephalus)

This report describes a computerized apparatus and procedure for completely automated noninvasive measurement of systolic, diastolic, and mean arterial blood pressure in conscious, unrestrained nonhuman primates. We used a specially constructed, cage-mounted oscillometric blood pressure instrument and operant reward conditioning methods to train adult baboons(Papio cynocephalus) to submit voluntarily to frequent self-initiated determinations of their blood pressures in the absence of a human operator/observer. Details concerning the operant training procedure and illustrative blood pressure data are presented. The accuracy of the method was evaluated by comparing the noninvasive blood pressure readings with simultaneously taken direct measurements obtained by means of chronically indwelling arterial catheters.     

Extinction of morphine analgesic tolerance

It has been suggested that the analgesic effect of morphine becomes attenuated over the course of successive administrations by a conditional, compensatory, hyperalgesic response elicited by the administration procedure, thus accounting (in part) for analgesic tolerance. On the basis of this associative model of tolerance, it would be predicted that established tolerance would be extinguished by placebo sessions. In experiments of apparently similar design (but conducted by different experimenters in different laboratories), data both confirming and refuting this prediction have previously been published. The present experiment, conducted jointly by the experimenters who reported the divergent findings, was designed to determine the reasons for the different results. It was found that placebo sessions do consistently attenuate morphine analgesic tolerance. Such extinction is not limited to the experimenter, drug preparation, rat strain, or apparatus used in the original, successful demonstration of the phenomenon, but rather is also demonstrable under conditions similar to those used in subsequent experiments which failed to demonstrate extinction of tolerance. Results of the present experiment suggest that the failures to demonstrate extinction of tolerance were attributable to insufficient extinction training.     

Determinants of social perception in a naturalistic setting

Based upon the assumption that personality traits exist more in the eye of the observer than is actually reflected in the actions of the actor, Jones and Nisbett have proposed that a negative relationship exists between familiarity with an actor's behavioral history and the tendency to attribute traits to that individual. An alternative viewpoint is suggested by the present research. Members of a college fraternity attributed more personality traits to themselves than were attributed to them by their fellow members. In addition, the fraternity members tended to offer more dispositional attributions to other members with whom they were more familiar. Furthermore, evidence is presented that is suggestive of the validity of these attributions. It is concluded that the attribution of personality traits provides attributors with information that is both veridical and useful in guiding social interactions.     

Environmental adaptation of the mental patient

An ecological model suggests looking at the hospitalized mental patient in terms of how well the resources available in the environment fit his individual needs. This study explores the relationship between the environmental fit of patients while they are in the hospital and their adaptation to the community once they have left. Data on individual needs and evaluations of environmental resources were obtained through a series of structured interviews. Results indicate that the more a patient feels the hospital environment is a good fit, the longer he stays there. Hospital fit is positively related to fit in the community, but the latter is related only to the degree of symptomatology exhibited by the expatient in the community and not to how long he is able to remain out of the hospital. Implications of the findings and the model are discussed.