DOES CONTINGENT REINFORCEMENT STRENGTHEN OPERANT BEHAVIOR?

In Experiment 1, pigeons were trained to peck keys with equal food-reinforcement schedules in components that ended with either noncontingent or contingent transitions to a third component with a five-fold richer schedule. Response rates were higher in the initial component with contingent transitions, but resistance to prefeeding or extinction was not consistently greater. Experiment 2 also included noncontingent or contingent transitions to a signaled period of nonreinforcement. There was no effect of the contingency on transitions to nonreinforcement, but the difference in response rates maintained by contingent versus noncontingent transitions to the richer schedule was replicated. In addition, response rates were higher in components that preceded nonreinforcement than in components that preceded the richer schedule. However, resistance to extinction was greater for noncontingent transitions to the richer schedule than to nonreinforcement, implicating stimulus–reinforcer relations in the determination of resistance to change. Resistance to change was also somewhat greater for noncontingent than for contingent transitions to the richer schedule. The latter result, together with the results of Experiment 1 and related research, suggests that response-contingent reinforcement does not increase resistance to change.     

Apraxia in a patient with atypical cerebral dominance

Liepmann postulated that the left hemisphere of right-handed persons contains the "movement formulas" that control purposeful skilled movements of the limbs on both sides of the body. Accordingly, in right-handers apraxia should follow damage to the left hemisphere, whereas right hemisphere damage should not lead to apraxia. Although this is generally true, we recently examined a right-handed man who after a right hemispheric stroke became aphasic and apraxic with his nonparalyzed right hand. Our observations suggest that the right hemisphere of this right-handed man made a critical contribution to the planning and execution of skilled movements. This case provides evidence that right-handers should not be considered a homogeneous group in terms of cerebral motor dominance and that contrary to Liepmann's postulate, hemispheric dominance for the control of skilled movements does not entirely determine handedness.     

Acute neuropsychological consequences of coronary artery bypass surgery

This study examines a series of coronary artery bypass patients (CABS) for neuropsychological and regional cerebral blood flow (RCBF) changes at 8 days and 8 weeks post surgery. Seventy-three percent were found to have moderate or severe neuropsychological deficits at 8 days post operation and 37% at 8 weeks post surgery. A comparison group of major vascular and thoracic surgery patients was also found to have a significant proportion of neuropsychological deficit following surgery. The RCBF assessments indicated a significant drop in mean RCBF at 8 days post surgery in the coronary artery bypass group which did not persist to 8 weeks. The comparison group showed no changes in RCBF following surgery. The findings suggest different patterns of recovery and origins of the neuropsychological deficit in the two groups and emphasize the need for appropriate control groups in studies examining the cortical effects of extracorporeal circulation. In addition, the project received generous support from the special trustees of the Middlesex Hospital.     

Perceived control and health

Perceived control (PC) is defined as thebelief that one can determine one’s own internal states and behavior, influence one’s environment, and/or bring about desired outcomes. Two important dimensions of PC are delineated: (1) whether the object of control is located in the past or the future and (2) whether the object of control is over outcome, behavior, or process. A variety of constructs and measures of PC (e.g., efficacy, attribution, and locus of control) are discussed in relation to these dimensions and selected studies are reviewed. The issues, controversies, and limits of the research on perceived control and health are addressed in terms of the antecedents and consequences of perceived control. Investigations should clearly conceptualize the object of perceived control, use measures that match the conceptualization, and when attempting to manipulate control, directly measure perceived control. The relation between PC and health outcomes is complex, and different aspects of PC may interact to affect health outcomes.     

Optimism, neuroticism, coping, and symptom reports: an alternative interpretation of the Life Orientation Test

Found in two studies that the Life Orientation Test (LOT) had limited discriminant validity relative to measures of neuroticism. Furthermore, although previous correlations of the LOT with measures of symptom reports and coping behaviors were replicated, these correlations were eliminated when neuroticism was controlled. In contrast, the correlations of symptoms and coping with neuroticism remained significant when LOT scores were controlled. Thus, the LOT is virtually indistinguishable from measures of neuroticism, and previously reported findings using this scale are perhaps more parsimoniously interpreted as reflecting neuroticism rather than optimism. These findings are discussed in terms of existing support for models of optimism and self-control and general methodological issues in studies of personality and health.     

A brief scoring method for voice stress analysis

The Psychological Stress Evaluator (PSE) detects inaudible frequency changes in the human voice, and it is claimed that the pattern of these changes can provide a measure of psychophysiological arousal. A few studies have given some support to this hypothesis, but further clarifica tion is needed. One major technical problem in this research is that the traditional scoring esyStem is unreliable unless considerable numbers of scores are taken and averaged , The paper presents a conveniently brief scoring system which has fair reliahility, and which correlates significantly with a measure of Critical Flicker Fusion Threshold.     

Detection of auditory signals occurring at random times: Intensity and duration

Observers attempted to detect a weak auditory signal presented in noise. The onset of the signal was determined by a Poisson process, and only responses occurring 1 sec after signal onset were considered detections. Three latency distributions were measured, the time to a signal onset, the reaction time distribution, and the false-alarm distribution (of responses occurring before a signal onset). A simple two-state model is proposed to account for a discrepancy between the distribution of signal waits and the distribution of false alarms. The hazard functions of the reaction time distributions are considered in detail and a simple accumulation model is proposed to account for the results.