Altruism in surgery of AIDS patients

There is usually a long period of time between infection with the AIDS virus and manifestation of symptoms. Asymptomatic patients often would benefit from elective surgery for diseases such as arthritis which are unrelated to their infection. The surgeons' decisions to accept the risks to themselves, their spouses, and their operating teams in order to relieve pain and suffering appear to be based upon two covenants; one concerns their role within the doctor-patient relationship, and the other concerns their relationship to what they see as the ultimate meaning in life.     

Dispersion in models of categorical perception

A signal detection theory model of auditory discrimination with a nonlinear mapping from stimulus continuum to perceptual continuum can account for the enhanced discrimination at the category boundary found in categorical perception. Properties of this transformation are specified by a unimodal “dispersion function”. Furthermore, it is shown that a system consisting of two acoustic feature detectors with an associated decision function is also a dispersive system, which models categorical perception of a stimulus continuum as well as boundary shifts under adaptation. The effect of detector adaptation on discrimination is discussed in view of three different types of decision variable and different types of detector noise.     

Structure and development of behavior systems

Behavior systems are particular organizations of cognitive structures that are called behavior mechanisms: perceptual, central, and motor. Thus, behavior systems are defined here in structural terms and not in terms of their functional characteristics. In young animals, behavior mechanisms often develop independently of functional experience, though specific types of experience are usually necessary for integrated systems to develop. These concepts are illustrated here by the dust-bathing, feeding, aggressive, and sexual systems of the fowl, which are considered to be typical of behavior systems in other species. Aspects of neural development are examined and found to facilitate our understanding of a wide range of developmental phenomena, such as critical periods and irreversibility. Finally, various examples of classical conditioning and instrumental learning are analyzed in terms of the type of structures involved, and they are related to general developmental processes.     

Varieties of positive and negative priming

Numerous recent investigations have focused on a particular relation between the roles a stimulus plays in successive displays: when a stimulus ignored by a subject on one occasion is to be attended on a succeeding occasion, reaction time to that stimulus is slowed relative to a control condition. But this is but one possible case ofnegative priming. There are other ways in which negative priming might occur, and there are several varieties of positive priming as well. All these possibilities were explored in the present experiment.     

Behavior of depressed subjects in problem solving groups

This study investigated leadership selection in groups in relation to level of depression of group members. On the basis of MMPI-D and DACL scores 66 subjects were organized into groups of six to eight people consisting of all depressed, all nondepressed, or half depressed and half nondepressed subjects. Subjects performed a problem solving task alone and in groups and completed a questionnaire on leadership choice and group performance. Results indicate that nondepressed group members talked more frequently, were rated as more important contributors, and were selected as leaders more frequently than depressed members. In addition, mixed groups were perceived as more efficient and enjoyable by group members than the unmixed groups. There were no significant differences between depressed and nondepressed subjects on performance of the problem solving task whether working alone or in groups. Results were discussed in relation to other literature on the interpersonal behavior of depressed persons.