Environment and Physical Activity Dynamics: The Role of Residential Self-selection

OBJECTIVES: Within the socio-ecologic framework, diet and physical activity are influenced by individual, interpersonal, organizational, community, and public policy factors. A basic principle underlying this framework is that environments can influence an individual's behavior. However, in the vast majority of cross-sectional and even the few longitudinal studies of this relationship, the question of whether individuals select their area of residence based on physical activity-related amenities is ignored. In this paper, we address a critical methodological issue: self-selection of residential location, which is generally not accounted for, and can significantly compromise research on the relationship between environmental factors and physical activity behaviors. METHOD: We define and discuss the problem of residential self-selection in the study of neighborhood influences on health and health behavior, review methods used to control for residential self-selection in the literature, and present our strategy for addressing this potentially important source of bias. CONCLUSION: Existing research has built our understanding of residential self-selection bias, but important gaps remain. Our strategy uses data from a longitudinal cohort study linked to contemporaneous environmental measures to create a multi-equation model system to simultaneously estimate residential choice, environmental influences on physical activity, and downstream health outcomes such as obesity and clinical cardiovascular disease risk factor measures.     

Human performance on negative slope schedules of points exchangeable for money: a failure of molar maximization

Panel pressing was generated and maintained in 5 adult humans by schedules of points exchangeable for money. Following exposure to a variable-interval 30-s schedule and to a linear variable-interval 30-s schedule (which permitted points to accumulate in an unseen "store" in the absence of responding), subjects were exposed to a series of conditions with a point-subtraction contingency arranged conjointly with the linear variable-interval schedule. Specifically, points were added to the store according to the linear-variable interval 30-s schedule and were subtracted from the store according to a ratio schedule. Ratio value varied across conditions and was determined individually for each subject such that the subtraction contingency would result in an approximately 50% reduction in the rate of point delivery. Conditions that included the subtraction contingency were termed negative slope schedules because the feedback functions were negatively sloped across all response rates greater than the inverse of the variable-interval schedule, in this case, two per minute. Overall response rates varied inversely with the subtraction ratio, indicating sensitivity to the negative slope conditions, but were in excess of that required by accounts based on strict maximization of overall reinforcement rate. Performance was also not well described by a matching-based account. Detailed analyses of response patterning revealed a consistent two-state pattern in which bursts of high-rate responding alternated with periods of prolonged pausing, perhaps reflecting the joint influence of local and overall reinforcement rates.     

Validation of the psychopathic personality inventory on a female inmate sample

This investigation evaluated the construct validity of the Psychopathic Personality Inventory (PPI; Lilienfeld & Andrews, 1996), a self-report measure designed to assess psychopathy. One hundred and two incarcerated females were administered the Kaufman Brief Intelligence Test (K-BIT), an oral alcohol and drug screening measure, a demographic interview, the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), the Psychopathy Checklist-Revised (PCL-R), and the PPI. There were significant correlations among the PPI, MMPI-2 scales, and the PCL-R. In addition, the correlations between the PPI and the separate PCL-R factors were not significantly different from each other, indicating that the PPI is assessing both facets of the psychopathy construct to some extent. A high correlation between the PPI and the DSM-IV criteria, which assesses adult antisocial behaviors, revealed adequate concurrent validity. Nonsignificant or negligible correlations between the PPI and the MMPI-2 scales provided some support for discriminant validity. The results are discussed with respect to the clinical and forensic utility of the PPI, the limitations of the study, and the need for further research.     

The sectored foraging field: a novel design to quantify spatial strategies, learning, memory, and emotion

Although Norway rats are naturally gregarious, males typically live alone at some point during adulthood. Different social ecologies often require different learning strategies and also modulate response to stressors and gonadal development. To measure effects of the social environment on the interaction between cognition and emotion during aging, we focused on a natural learning context and devised the sectored foraging field, a progressively difficult spatial navigation task. Here, we describe how this apparatus and protocol permits multiple learning strategies in a minimally stressful environment, enabling finely graded analyses of cognition and emotionality. Male Sprague-Dawley rats living alone throughout adulthood adopted a sex-typic discernible spatial strategy. In contrast, males housed in group contexts utilized an algorithmic kinesthetic strategy, repeating the same motor action until they found food. Removal of food and distal, but not local cues, elicited anxious alertness, particularly in group-housed males. Cognitive performance of group-housed rats subsequent to food and cue removal was significantly impaired, yet enhanced in isolates.     

Apraxia differs in corticobasal degeneration and left-parietal stroke: A case study.

Corticobasal degeneration (CBD) is a progressive disorder characterized by both cortical and basal ganglia dysfunction such as asymmetrical apraxia, and akinetic rigidity, involuntary movements, and cortical sensory loss. Although apraxia is a key finding for the differential diagnosis of CBD, it has not been determined whether the features of apraxia seen in subjects with CBD are similar to those features exhibited by subjects with left-hemisphere damage from stroke. Therefore, for both clinical purposes and in order to better understand the brain mechanisms that lead to apraxia in CBD, we studied praxis in a patient with CBD and compared him to patients who are apraxic from left-parietal strokes. We used three-dimensional movement analyses to compare the features of apraxic movement. This subject with CBD was a dentist whose initial complaint had been that he "forgot" how to use his tools in the mouths of his patients. Analyses were performed on the trajectories made when using a knife to actually slice bread, and when repetitively gesturing slicing made to verbal command. Movements of the left hand, wrist, elbow, and shoulder were digitized in 3-D space. Although the CBD subject was clearly apraxic, the features of his apraxia differed markedly from those of the subjects with lesions in the left parietal lobe. For movements to command, the CBD subject showed joint coordination deficits, but his wrist trajectories were produced in the appropriate spatial plane, were correctly restricted to a single plane, and, like control subjects, were linear in path shape. However, when he was actually manipulating the tool and object, all of these aspects of his trajectories became impaired. In contrast, the deficits of the apraxic subjects with left-parietal damage were most pronounced to verbal command with their movements improving slightly although remaining impaired during actual tool and object manipulation. Unlike patients with parietal strokes, patients with CBD have degeneration in several systems and perhaps deficits in these other areas may account for the differences in praxic behavior.     

Definitions of physical abuse: A preliminary inquiry into children's perceptions

Research and policy-makers have frequently called for operational definitions of child abuse, however neither group has considered including children's perceptions of what constitutes abuse. The purpose of this study was to expand the discussion on definitions of child abuse by examining children's perceptions of physical abuse. This was done by collecting data to begin to document abused children's ratings of the seriousness of various abusive acts and to begin to examine gender and age differences in children's perceptions. The data revealed significant differences in children's perceptions of the seriousness of specific acts of abuse and a significant interaction between age and type of abuse. Although young children generally produced lower seriousness ratings than older children, their ratings were significantly lower on only a few types of abuse. When children's ratings were compared to similar ratings reported in earlier studies of adolescents, community members, and mental health professionals, the children in this study rated the abusive acts as less serious than the adolescents or community members, but very similar to the professionals who work in the area of child abuse and neglect. Although this must be considered a preliminary investigation, the potential implications for various legal and social contexts are discussed.     

Gender-Role Cognition in Three-Year-Old Boys and Girls

Although the multidimensionality of gender roles has been well established, few researchers have investigated male and female roles separately. Because of the substantial differences in the ways male and female roles are portrayed in our culture, boys and girls may think and learn about these roles differently. The male role is more clearly defined, more highly valued, and more salient than the female role; thus, children's cognitions about these two roles may be expected to differ. The present study addressed the question of whether there is sex-typical variation in gender labeling, gender-role knowledge, and schematicity. Participants were 120 families; 15% were from minority ethnic groups, and 17% were single-parent families; 25% of the parents had a high school education or less. Results indicated that at 36 months of age, boys were less able to label gender and less knowledgeable about gender roles than were girls. Boys' knew more about male stereotypes than female stereotypes, whereas girls knew considerably more than boys about the female role and as much as boys about the male role. Boys and girls were found to be similar in gender schematicity. Traditionality of parental attitudes regarding child-rearing and maternal employment were not strongly related to children's gender cognition.     

Fast temporal dynamics of visual cue integration

The integration of information from different sensors, cues, or modalities lies at the very heart of perception. We are studying adaptive phenomena in visual cue integration. To this end, we have designed a visual tracking task, where subjects track a target object among distractors and try to identify the target after an occlusion. Objects are defined by three different attributes (color, shape, size) which change randomly within a single trial. When the attributes differ in their reliability (two change frequently, one is stable), our results show that subjects dynamically adapt their processing. The results are consistent with the hypothesis that subjects rapidly re-weight the information provided by the different cues by emphasizing the information from the stable cue. This effect seems to be automatic, ie not requiring subjects' awareness of the differential reliabilities of the cues. The hypothesized re-weighting seems to take place in about 1 s. Our results suggest that cue integration can exhibit adaptive phenomena on a very fast time scale. We propose a probabilistic model with temporal dynamics that accounts for the observed effect.