Aversive properties of the negative stimulus during learning with and without errors

In a successive discrimination four groups of pigeons were trained to discriminate between red and green. The groups differed with respect to the procedure used to introduce S?: Early-Progressive, Early-Constant, Late-Progressive, and Late-Constant. The aversive properties of S? were measured by an escape response in which a single peck at a second key terminated S? for 10 sec and darkened the chamber. The correlation between the aversive and error-producing properties of extinction was zero. More errors occurred when S? was introduced abruptly at a constant intensity while more timeouts from S? occurred when S? was introduced late. The procedure for introducing S? rather than the number of responses to S? appears crucial in determining how aversive S? becomes.     

Preventing weight gain in adults: a pound of prevention

This study evaluated the feasibility and effectiveness of a program for weight gain prevention in normal-weight adults. Two hundred nineteen participants were randomized to either weight gain prevention treatment or no treatment for a period of 12 months. Those in the treatment group received monthly newsletters relating to weight management, participated in a financial incentive system, and were offered an optional four-session education course in the sixth month of the program. Results demonstrated high interest in weight gain prevention among individuals who were not objectively overweight. Participation, as measured by return of postcards sent with each newsletter, was approximately 75%. Results after 1 year showed a net weight loss in the group receiving the program of 1.8 lb compared to those in the control group. Eighty-two percent of program participants maintained or lost weight, compared to 56% of the control group. It is concluded that programs for weight gain prevention are feasible in adults and may be more effective than weight loss treatment programs in addressing the problem of community-wide obesity.     

Modifying food purchases in supermarkets with modeling, feedback, and goal-setting procedures

We compared several procedures designed to modify consumer food purchases with the objectives of reducing fat and increasing carbohydrate content, and reducing dollar expenditures on food. Participants were 126 volunteer community households which, after a 7-week baseline period, were randomly assigned to video-modeling, video-modeling-feedback, video-lecture, video-lecture-feedback, participant-modeling, video-modeling-discussion, and control conditions. The main dependent measure was a weekly record of food purchases, convertible to percentages of nutrients and dollar expenditures. Results indicated that modeling-feedback and participant-modeling procedures were most effective (e.g., 6% reduction of total fat consumption, 19% dollar savings). Strategies to refine and automate modeling and feedback in supermarkets that may benefit consumers, corporations, and government are discussed.     

Neurobehavioral and psychosocial functioning of women exposed to high altitude in mountaineering

The effects of chronic hypoxemia upon cognition and behavior were studied in women exposed to high altitude in mountaineering. Neuropsychological tests and psychosocial and physiological questionnaires were given to eight women before, during, and immediately after a Himalayan climb to 20,500 feet. Cognitive functioning remained relatively intact with only two significant decrements, complex abstract reasoning and word-finding ability. Significant changes were found on all psychosocial and physiological questionnaires. Feelings of acceptance of others and anxiety declined significantly. Physical symptoms were greatest during the first five days of ascent. Subjects' self-ratings of mental functioning were significantly better after the expedition than either before or during the climb. Self-assessments were correlated with emotions and physical symptoms, not with actual performances on the test battery. It is suggested that complex cognitive tasks and psychosocial functioning be studied in more detail as these were more influenced by exposure to high altitude in mountaineering.     

The differential impact of criminal stigmatization on male and female felons

By way of survey-experimental methods, stigmatization responses of a college student sample and a community sample were examined to assess how sex of convicted felon and sex of subject affect levels of stigmatization. Major results were that (a) relatively high levels of stigmatization were expressed by subjects in both samples toward both male and female felons; (b) female felons, however, were the recipients of less stigmatization than male felons, with the difference being larger in the community than the student sample; and (c) sex of subject had little effect on the expression of stigmatization. It is suggested that the factors leading to less stigmatization of the female felon are nativeté concerning the female offender and greater fear of the male offender. Finally, attitudinal and background correlates of stigmatization are examined.     

Fruitful visual search: Inhibition of return in a virtual foraging task

Inhibition of return (IOR) has long been viewed as a foraging facilitator in visual search. We investigated the contribution of IOR in a task that approximates natural foraging more closely than typical visual search tasks. Participants in a fully immersive virtual reality environment manually searched an array of leaves for a hidden piece of fruit, using a wand to select and examine each leaf location. Search was slower than in typical IOR paradigms, taking seconds instead of a few hundred milliseconds. Participants also made a speeded response when they detected a flashing leaf that either was or was not in a previously searched location. Responses were slower when the flashing leaf was in a previously searched location than when it was in an unvisited location. These results generalize IOR to an approximation of a naturalistic visual search setting and support the hypothesis that IOR can facilitate foraging. The experiment also constitutes the first use of a fully immersive virtual reality display in the study of IOR.     

Role of muscarinic M1 receptors in inhibitory avoidance and contextual fear conditioning

The objective of the present study was to observe the effects of pre-training or post-training administration of dicyclomine, a M1 muscarinic antagonist, on inhibitory avoidance (IA) and contextual fear conditioning (CFC) and to investigate if the effects observed with the pre-training administration of dicyclomine are state-dependent. For each behavioral procedure (IA and CFC) groups of Wistar male rats were treated with saline or dicyclomine either 30 min before training (pre-training), immediately after training or 30 min before training/30 min before test (pre-training/pre-test). The animals were tested 24 h after training. The acquisition of IA and CFC was impaired by pre-training administration of dicyclomine. The consolidation of both tasks was not affected by dicyclomine given immediately after training. Pre-training/pre-test administration of dicyclomine impaired both tasks, an effect similar to that observed in the group which only received pre-training administration. Pre-test treatment induced dissociation between both tasks, impairing CFC retrieval, without interfering with the animals avoidance response. These results show that the dicyclomine did not affect IA and CFC consolidation, suggesting specific involvement of M1 muscarinic receptor only in acquisition these tasks, and these effects was not state-dependent. However, it is possible that the retrieval of these tasks may be mediated, at least in part, by different neurochemical mechanisms and may be dissociated by dicyclomine.     

Training effects on dual-task performance: are there age-related differences in plasticity of attentional control?

A number of studies have suggested that attentional control skills required to perform 2 tasks concurrently become impaired with age (A. A. Hartley, 1992; J. M. McDowd & R. J. Shaw, 2000). A. A. Hartley (2001) recently observed that the age-related differences in dual-task performance were larger when the 2 tasks required similar motor responses. The present study examined the extent to which age-related deficits in dual-task performance or time sharing--in particular, dual-task performance of 2 discrimination tasks with similar motor requirements--can be moderated by training. The results indicate that, even when the 2 tasks required similar motor responses, both older and younger adults could learn to perform the tasks faster and more accurately. Moreover, the improvement in performance generalized to new task combinations involving new stimuli. Therefore, it appears that training can substantially improve dual-task processing skills in older adults.     

Development of attentional and oculomotor control

The present study was conducted to examine the development of attentional and oculomotor control. More specifically, the authors were interested in the development of the ability to inhibit an incorrect but prepotent response to a salient distractor. Participants, who ranged in age from 8 to 25 years, performed 3 different eye movement tasks: a prosaccade, an antisaccade, and an oculomotor capture task. The time required to initiate a saccade decreased with age across all 3 tasks. Consistent with previous reports, accuracy was relatively age invariant in the prosaccade task. Performance improved with age, asymptoting at 16 years in the antisaccade task. It is interesting to note that despite the superficial similarity of the antisaccade and oculomotor capture tasks, performance was relatively age invariant in the latter. These results are discussed in terms of developmental differences in the interaction of goal-directed and stimulus-driven processes in the control of attention and action.     

Attentional capture modulates perceptual sensitivity

The present study was designed to determine the spatial distribution of attention in displays in which an irrelevant color singleton was present. The results show that the presence of an irrelevant color singleton modulates target detectability (ď). The presence of an irrelevant singletonreduces the gain for input at the target location, particularly when the irrelevant color singleton was close to the target singleton. In line with earlier claims, it is argued that the capture of attention by the irrelevant singleton causes a reduced sensory input at the target location.