Effects of alternative reinforcement sources: A reevaluation

The effects of two alternative sources of food delivery on the key-peck responding of pigeons were examined. Pecking was maintained by a variable-interval 3-min schedule. In the presence of this schedule in different conditions, either a variable-time 3-min schedule delivering food independently of responding or an equivalent schedule that required a minimum 2-s pause between a key peck and food delivery (a differential-reinforcement-of-other-behavior schedule) was added. The differential-reinforcement-of-other-behavior schedule reduced response rates more than did the variable-time schedule in most instances. The delay between a key peck and the next reinforcer consistently was longer under the differential-reinforcement-of-other-behavior schedule than under the variable-time schedule. Response rates and median delay between responses and reinforcers were negatively correlated. These results contradict earlier conclusions about the behavioral effects of alternative reinforcement. They suggest that an interpretation in terms of response–reinforcer contiguity is consistent with the data.     

Discrimination learning in a foraging situation

Rats were allowed to forage in a simulated natural environment made up of eight food sources (patches) each containing a fixed number of pellets. Two of the eight contained an extra supply of peanuts. The peanut patches were signaled by an olfactory/visual cue located at the bottom of the ladder leading to the patch. In successive phases the number of sessions per day, height of the patches, and availability of peanuts were manipulated. Subjects showed evidence of discrimination learning under these conditions, although the degree of discriminatory behavior varied as a function of environmental manipulations. Assessment of behavior within foraging sessions showed that subjects systematically changed their patterns of utilization of patches across time. Sampling or exploration, as well as food reinforcement, seem implicated in these results.     

Pigeons can discriminate locations presented in pictures

The present experiments were designed to teach pigeons to discriminate two locations represented by color photographs. Two sets of photographs were taken at two distinctive locations on a university campus. These sets represented several standpoints at each location. For the true-discrimination group, pictures from the two locations were differentially associated with reward; for the pseudodiscrimination group, half of the views from each location were arbitrarily but consistently associated with reward. The former group acquired the discrimination much more rapidly. These birds also showed good transfer to new views from the standpoints used in training and to a new standpoint at each location not used in training. In a second experiment, another group of pigeons could terminate any training trial by pecking an “advance” key. Three of 4 subjects used this option to reduce the duration of trials in which pictures from the negative location were presented. These data suggest that pigeons can integrate views shown in pictures into a “concept” of a location. The method used here may be the experimental analogue of a common, natural process by which animals learn to identify locations.     

Accuracy of estimations of body-frame size as a function of sex and actual frame size

Body-frame size is an important factor in determining an optimal body weight for a given height. Previous studies have indicated that many individuals incorrectly estimate their body-frame size, and, as a result, incorrectly assess their ideal weight. The present study investigated the accuracy of estimation of body-frame size as a function of sex and actual frame size. The subjects were 66 men and 52 women participating in a community adult fitness program. Data indicated that medium-framed individuals were the most accurate in their estimations of body-frame size. Also, women were twice as likely to be accurate as were men. These results are interpreted to mean that most people assume they are medium-framed and that there is a sex difference in the way body-frame size is estimated.     

WORK LOAD, TENSION, AND COPING: MODERATING EFFECTS OF SUPERVISOR SUPPORT

This research investigated the buffering role of social support in the relationship of work load to both tension-anxiety and coping for police radio dispatchers ( N = 60). Each dispatcher was observed throughout an entire 8-hour work shift by a trained observer. Objective load consisted of the hourly rate of incoming telephone calls, police radio transmissions, and face-to-face or written communications from superiors, co-workers, and others. At the end of each shift, measures were taken of dispatchers' perceived load, felt tension-anxiety, and coping actions. Hierarchical regression revealed that support from superiors moderated the effects of both objective and perceived loads; no main effects of support were found. Statistically significant interactions confirmed the hypothesized buffering role of support: under high perceived load, dispatchers with high social support engaged in more coping actions and felt less tension-anxiety than did low-support dispatchers. No differences were found when perceived load was low. Support also buffered effects of objective load on tension-anxiety but not on coping.     

Forensic psychiatric assessment in the USSR

Basing on the author's experiences during his study stay at the Serbsky All-Union Research Institute for General and Forensic Psychiatry in Moscow a report is given about the theoretical foundations and the carrying-out of forensic-psychiatric expert-opinions in the field of penal as well as civil law in the U.S.S.R. Some peculiarities in comparison with the practice in the G.D.R. are taken in special account.