Changes in feeding and foraging patterns as an antipredator defensive strategy: a laboratory simulation using aversive stimulation in a closed economy.

The effects of the risk of electric shock on the meal patterns of rats living in an operant chamber were investigated. Rats could obtain food by working on a response lever that provided reinforcement according to chained fixed-ratio continuous reinforcement schedules that allowed the animals control over meal size. Using a two-compartment operant chamber with a safe nesting area and manipulanda area with a grid floor, shock could be correlated with responding on the schedule. Shocks (less than or equal to 1.25 per hour) were scheduled to occur randomly throughout the day, independent of the rat's behavior. Shock caused a reorganization of meal patterns such that the animals took less frequent but larger meals. This pattern reduced the time the animals spent at risk without compromising caloric balance. Similar changes in feeding pattern were obtained in both hooded and albino rats. Exposure to shock in a separate chamber did not produce these behavioral modifications. The magnitude of shock-induced alterations of meal patterns was greater with chained fixed-ratio 90 continuous reinforcement than with chained fixed-ratio 10 continuous reinforcement. Additionally, the rats seemed to be able to reduce food intake but increase caloric efficiency, such that the reduced food intake did not have deleterious effects on maintenance of body weight. These behavioral modifications reduced the number of shocks received from that which would have been expected if meal pattern changes had not occurred. We suggest that this technique may provide a useful laboratory simulation of the impact that the risk of predation has on foraging behavior.     

Within-session meal-size effects on induced drinking.

As a control for the effects of session duration and hunger on the relation between food magnitude and induced drinking, four food-deprived rats were exposed to a variable-time 50-s schedule of food delivery in which the size of each food delivery varied randomly within sessions. Food-related behavior and schedule-induced drinking per opportunity were examined as functions of meal size and postfood time. All rats showed an inverted-U-shaped relation between drinking per opportunity and meal size. This relation was caused by variation in the percentage of intervals that contained drinking and by variation in the number of drinking bouts per interval, rather than by bout duration or by the amount of drinking within those intervals that actually contained drinking. Head-in-feeder time increased linearly with meal size. Schedule-induced drinking was entrained by food delivery in 3 of 4 subjects; the entrainment was due to regulation of the starting time of each drinking bout rather than to regulation of bout duration.     

On the distinction between open and closed economies.

Open and closed economies have been assumed to produce opposite relations between responding and the programmed density of reward (the amount of reward divided by its cost). Experimental procedures that are treated as open economies typically dissociate responding and total reward by providing supplemental income outside the experimental session; procedures construed as closed economies do not. In an open economy responding is assumed to be directly related to reward density, whereas in a closed economy responding is assumed to be inversely related to reward density. In contrast to this predicted correlation between response-reward relations and type of economy, behavior regulation theory predicts both direct and inverse relations in both open and closed economies. Specifically, responding should be a bitonic function of reward density regardless of the type of economy and is dependent only on the ratio of the schedule terms rather than on their absolute size. These predictions were tested by four experiments in which pigeons' key pecking produced food on fixed-ratio and variable-interval schedules over a range of reward magnitudes and under several open- and closed-economy procedures. The results better supported the behavior regulation view by showing a general bitonic function between key pecking and food density in all conditions. In most cases, the absolute size of the schedule requirement and the magnitude of reward had no effect; equal ratios of these terms produced approximately equal responding.     

Human Performance Under Progressive Ratio Contingencies

The Psychological Record - Ten human subjects experienced a progressive ratio schedule under three different reinforcement conditions; (a) 20-point increments on a computer screen for each ratio...     

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.     

Accepting personality test feedback: A review of the Barnum effect

This article attempts a comprehensive and critical review of the by-now fairly extensive literature on the Barnum effect—the approval/acceptance by subjects of bogus personality interpretations supposedly derived from standard tests. Since the last major review eight years ago various methodological extensions have occurred and various rival hypotheses for established findings have been proposed. The present review is divided into three major sections: client and clinician characteristics; feedback statements and test format; and implications for personality assessment and measurement. Nearly 50 studies on the acceptance of personality interpretations are systematically reviewed and criticized.     

The role of cognition and coping in health behavior outcomes of asthmatic patients

This study investigates the meaning of cognitions and coping in well-being, hospital admissions, medication consumption, and absence from work due to asthma in asthmatic patients. Patients completed five questionnaires: the Respiratory Illness Opinion Survey (Kinsman, Jones, Matus, & Schum, 1976), measuring external control, psychological stigma, and optimism; the Asthma Coping Questionnaire (Maes, Schl?sser, & Vromans, 1986), measuring coping mechanisms; the Dutch version of the STAI (van der Ploeg, Defares, & Spielberger, 1979), measuring state and trait anxiety; the Questionnaire for Inner Well-Being (Hermans & Tak-van de Ven, 1973), measuring well-being; and the General Questionnaire for Asthmatic Patients (Maes et al., 1986) measuring medical outcome. Stepwise multiple regression showed that cognitions and coping determined a considerable part of the variance in the dependent variables: well-being, hospital admissions, and absence from work due to asthma.     

Determinants of seeking timely and necessary pediatric care

Ninety mothers were interviewed in a pediatrician’s waiting room about their reasons for seeking care. We compared their answers, and the pediatrician’s judgment of the visit’s necessity and timeliness to a model which distinguishes appraisal, illness, and utilization stages in seeking medical treatment. Clearly defined symptoms and the use of few home treatments predicted a more rapid assessment that one’s child was ill. No factors predicted how quickly a mother would decide that her child needed professional care, nor how rapidly she would then seek that care. The pediatrician judged visits to be necessary when the child had many physical symptoms, pain, and/or fever, and when the child’s mother was employed. He judged visits to be delayed for mothers who reported that cost of treatment may influence their decisions to seek care. He indicated that only 39% of the visits were both necessary and on time. We discuss ways to encourage appropriate utilization of pediatric visits.