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PubMed1998

Overview of the Activity Counseling Trial (ACT) intervention for promoting physical activity in primary health care settings. Activity Counseling Trial Research Group.

Counseling by health care providers has the potential to increase physical activity in sedentary patients, yet few studies have tested interventions for physical activity counseling delivered in health care settings. The Activity Counseling Trial (ACT) is a 5-yr randomized clinical trial to evaluate the efficacy of two primary care, practice-based physical activity behavioral interventions relative to a standard care control condition. A total of 874 sedentary men and women, 35-75 yr of age, have been recruited from primary care physician offices at three clinical centers for 2 yr of participation. They were randomly assigned to one of three experimental conditions that vary, in a hierarchical fashion, by level of counseling intensity and resource requirements. The interventions, which are based on social cognitive theory and the transtheoretical model, are designed to alter empirically based psychosocial mediators that are known to be associated with physical activity. The present paper describes the theoretical background of the intervention, the intervention methods, and intervention training and quality control procedures.

Adult↗
PubMedDate not supplied

Somatization disorder in sphincter of Oddi dysfunction.

OBJECTIVE: Sphincter of Oddi dysfunction (SOD) is a biliary disorder with a recognized pathophysiology and demonstrated surgical treatment. We sought to examine whether women with SOD were overrepresented on measures of somatization, sexual and physical abuse, socially compliant attitudes, and familial psychiatric illness. METHOD: We matched 33 women with SOD to 33 normal controls by age, sex, and race, and, with a case-controlled cross-sectional questionnaire, compared the groups on the study variables. Statistics included a chi 2 for categorical variables, t tests for scores of somatization and attitudes of social desirability, and Pearson correlation coefficients for post hoc associations of variables. Bonferroni corrections were used with chi 2 values to reduce capitalization by chance. RESULTS: SOD patients exhibited excessive nongastroenterological somatic complaints compared with controls (p < .0001). There was a statistical increase in reports of childhood sexual, but not physical, abuse in the SOD women (p < .02) compared with controls. The severity of the abuse correlated strongly with the severity of somatic complaints. There were no differences in social desirability attitudes or family psychiatric histories of the two groups. CONCLUSIONS: We conclude that SOD is associated with a high degree of somatization in adulthood, and a mean rate more than four times that of controls in self-reports of sexual abuse in childhood. The severity of childhood sexual abuse is correlated with the severity of somatization in later life. A psychological model for this disorder is suggested by the data. Increased psychiatric attention is indicated in the treatment of women with this disorder.

Case-Control Studies↗
PubMedDate not supplied

A transactional model of cancer family caregiving skill.

Family caregivers of persons receiving treatment of cancer must acquire illness-related skills not usually found among nonprofessional caregivers. Although research is needed to understand the skill acquisition process, no models of family caregiving skill exist to guide such research. The purpose of this study was to develop a model of caregiving skill through qualitative research. Participants were 44 caregiver/patient dyads and 63 individual caregivers. Data were collected using a semi-structured interview. A transactional model of family caregiving skill was developed that includes the concepts of demands of the illness situation, patterns of care, caregiver responses, and patient responses.

Adult↗
PubMedDate not supplied

Implementing a predictive modeling program, part 1.

Effective predictive modeling is a powerful, statistically valid tool, which identifies individuals at increased future risk of an untoward health event. This article looks at one company's experience in developing a successful program; the issues related to an effective implementation strategy; and lessons learned during the process. The goal is to implement the right intervention, at the right time, for the right patient.

Algorithms↗
PubMed2005

Investigating the structure of craving using structural equation modeling in analysis of the obsessive-compulsive drinking scale: a multinational study.

BACKGROUND: Currently, there is no agreement among researchers on the definition of craving and its underlying theoretical model. The Obsessive-Compulsive Drinking Scale (OCDS) seems to measure certain aspects of craving, but its theoretical basis remains unclear. The aim of this study was to investigate the structure of alcohol craving, using OCDS data. METHODS: OCDS data from four studies were pooled to obtain a large and heterogeneous sample of 505 participants. All participants were treatment-seeking alcoholics meeting DSM-IV criteria for alcohol dependence. The factor structures of the OCDS previously found were evaluated using confirmatory factor analyses. The goodness of fit of these solutions was compared with those of alternative causal models: an obsessive-compulsive disorder model, an inhibition model, and a cognitive-behavioral model. These alternative models were based on modern theories about craving and were tested in the OCDS data, using structural equation modeling. In this way, the current study replaced simple correlational analysis by a more sophisticated causal way of analyzing the underlying structure of the OCDS items. The best fitting model was selected by comparing the mean discrepancy between the implied and observed matrices of the models. RESULTS: The data showed that the previously reported factor structures had to be rejected. Also, the inhibition model and obsessive-compulsive disorder model did not fit the data. The cognitive-behavioral model showed encouraging fit. Optimizing strategies were applied to further improve the fit of this model, which resulted in a model with close fit to the data. CONCLUSIONS: The causal cognitive-behavioral model proved to be superior. It showed that the OCDS contains many items that do not represent the core concept of craving but instead are indicators for the consequences of craving. From this model, it seems that craving, in a narrow sense, can be reliably assessed with only five items of the OCDS.

Adult↗
PubMed2005

The role of war-zone trauma and PTSD in the etiology of antisocial behavior.

Historically, successful reintegration of war veterans into civilized society has been an enduring concern of nations. Data from the National Vietnam Veterans Readjustment Study were used to develop and evaluate an etiological model of postwar antisocial behavior. Two initial models specified causal paths among five sets of variables, ordered according to their historical occurrence: (a) premilitary risk factors, (b) military traumas and disciplinary actions, (c) the homecoming reception, (d) postmilitary PTSD and substance abuse, and (e) postmilitary antisocial behavior. PTSD and substance abuse were omitted in one model and included in the other. The initial models were refined and then cross-validated, leading to the specification of replicated models with highly satisfactory fit and parsimony. Comparison of the two models suggested that (1) premilitary experiences and behavior exert the largest effects on postmilitary antisocial behavior, and that (2) PTSD plays a necessary mediational role for the effects of war-zone traumatic exposure on postmilitary antisocial behavior.

Adult↗
PubMed1989

Early social status and the development of life-history strategies in Atlantic salmon.

Atlantic salmon have a variable life cycle. In good growing conditions, underyearling fish may metamorphose into the migratory smolt phase during their second spring, or delay at least a further year. The strategy adopted by particular fish appears to become fixed during their first summer. This paper examines whether either feeding efficiency or dominance in mid-summer correlates with the life-history strategy adopted. Eighty fish were individually marked and their feeding efficiency (= mean handling time for food items) and dominance rank measured under laboratory conditions in mid-July. Growth rates of the fish were then monitored over the next three months, until developmental strategies became apparent. Discriminant and logistic regression analyses revealed that both dominance rank and size attained by July were independent, significant predictors of future developmental pattern (the age at metamorphosis being correctly predicted on the basis of rank and size in 84% of cases) whereas feeding efficiency had no effect. Thus fish that were dominant or larger two months after first feeding or both had a greater probability of migrating after only one year in freshwater than those more subordinate or smaller or both.

Aging↗
PubMed1990

Motion-boundary illusions and their regularization.

Humans use various cues to understand the structure of the world from images. One such cue is the contours of an object formed by occlusion or from surface discontinuities. It is known that contours in the image of an object provide various amounts of information about the shape of the object in view, depending on assumptions that the observer makes. Another powerful cue is motion. The ability of the human visual system to discern structure from a motion stimulus is well known and has a solid theoretical and experimental foundation. However, when humans interpret a visual scene they use various cues to understand what they observe, and the interpretation comes from combining the information acquired from the various modules devoted to specific cues. In such an integration of modules it seems that each cue carries a different weight and importance. We performed several experiments where we made sure that the only cues available to the observer were contour and motion. It turns out that when humans combine information from contour and motion to reconstruct the shape of an object in view, if the results of the two modules--shape from contour and structure from motion--are inconsistent, they experience a perceptual result which is due to the combination of the two modules, with the influence of the contour dominating, thus giving rise to the illusion. We describe here examples of such illusions and identify the conditions under which they happen. Finally, we introduce a computational theory for combining contour and motion using the theory of regularization. The theory explains such illusions and predicts many more.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1992

Computational aspects of motion perception in natural and artificial vision systems.

In this paper a computational scheme for motion perception in artificial and natural vision systems is described. The scheme is motivated by a mathematical analysis in which first-order spatial properties of optical flow, such as singular points and elementary components of optical flow, are shown to be salient features for the computation and analysis of visual motion. The fact that different methods for the computation of optical flow produce similar results is explained in terms of the simple spatial structure of the image motion of rigid bodies. Singular points and elementary flow components are used to compute motion parameters, such as time-to-collision and angular velocity, and also to segment the visual field into areas which correspond to different motions. Then a number of biological implications are discussed. Electrophysiological findings suggest that the brain perceives visual motion by detecting and analysing optical flow components. However, the cortical neurons, which seem to detect elementary flow components, are not able to extract these components from more complex flows. A simple model for the organization of the receptive field of these cells, which is consistent with anatomical and electrophysiological data, is described at the end of the paper.

Artificial Intelligence↗
PubMed2000

Scramble in behaviour and ecology.

Nicholson's distinction between 'scramble' and 'contest' modes of competition has received widespread attention in ecology and in behaviour, though the emphasis has been different between the two disciplines. In ecology the focus has been on the effects on population; in behavioural ecology the focus has been on the consequences at the individual level. This paper reviews and develops a theory of scramble competition at the individual level, deriving a general evolutionarily stable strategy (ESS) for individual scramble expenditure in a patchy habitat in which individuals compete in local groups for available resources, and examines two population consequences. The critical parameter determining the relationship between individual scramble expenditure and the number of competitors in a patch is the expected resource per capita. If resource input, R, to a patch is constant and independent of the number of competitors, n, then as the number of competitors increases, the per-capita resources declines as R/n, and the ESS scramble level declines (in proportion to (n-1)/n2). However, if the resource input to a patch is positively related to the number of competitors in the patch, scramble expenditure may increase with the number of competitors. In the case where the per-capita resource input stays constant (i.e. R(n) = Rn), the scramble level increases with competitor number (in proportion to (n-1) /n). There are plausible ecological reasons why either of these extreme limits may be approached in nature, making it important to ascertain the relationship between R and n before predicting individual scramble expenditure. For example, resource input may be constant when groups of competitors are constrained to remain together in given patches, and constant per-capita resources may be approached when ideal-free foraging rules apply. However, in the latter case, scramble expenditure must be accounted for in determining the ideal-free distribution. An analysis shows that this leads to 'undermatching', i.e. the ratio of numbers of competitors for good/bad patches becomes progressively less than the ratio of input rates for good/bad patches as the difference between the good and bad patches increases. A second population consequence of the scramble ESS relates to the fact that scrambles may dramatically affect fitness. The per-capita gain in energy can be reduced by a factor of up to 1/n as a result of scramble expenditure, potentially reducing realized population size to as little as the square root of the maximum potential carrying capacity, though reasons are given why such large reductions are unlikely.

Animals↗
PubMed2004

A cognitive neuroscience framework for understanding causal reasoning and the law.

Over the past couple of decades, there have been great developments in the fields of psychology and cognitive neuroscience that have allowed the advancement of our understanding of how people make judgements about causality in several domains. We provide a review of some of the contemporary psychological models of causal thinking that are directly relevant to legal reasoning. In addition, we cover some exciting new research using advanced neuroimaging techniques that have helped to uncover the underlying neural signatures of complex causal reasoning. Through the use of functional imaging, we provide a first-hand look at how the brain responds to evidence that is either consistent or inconsistent with one's beliefs and expectations. Based on the data covered in this review, we propose some ideas for how the effectiveness of causal reasoning, especially as it pertains to legal decision-making, may be facilitated.

Brain↗
PubMed2004

On the role of anxiety in decisions under possiblistic uncertainty.

We focus on situations in which we must decide on what time to take an action. The action is not in question it is the time of action. We call these "time for action decisions," a prototypical example being deciding when to leave on a journey. We point out that during this type of decision process, the decision-maker recognizes two groups of forces acting on him: one that pushes him to act now and other that pushes him act later. We note that the strength of these forces depends on the information available about various uncertainties associated with the situation. It also strongly depends upon the personality of the decision-maker. We observe that as time passes these conflicting forces tend to build up an anxiety in the decision-maker resulting in an action being taken at a time of most intense anxiety. In this paper using the ideas of possibility and necessity measures to enable different interpretations of uncertain information we investigate the temporal profile of the decision-maker's anxiety as a function of their decision attitude. We investigate the role of maximization of anxiety as decision paradigm. One of our goals here is to try to understand role of the nature and the quality information plays in these types of decisions as well as its interaction with anxiety.

Anxiety↗
PubMed2003

A local influence approach applied to binary data from a psychiatric study.

Recently, a lot of concern has been raised about assumptions needed in order to fit statistical models to incomplete multivariate and longitudinal data. In response, research efforts are being devoted to the development of tools that assess the sensitivity of such models to often strong but always, at least in part, unverifiable assumptions. Many efforts have been devoted to longitudinal data, primarily in the selection model context, although some researchers have expressed interest in the pattern-mixture setting as well. A promising tool, proposed by Verbeke et al. (2001, Biometrics 57, 43-50), is based on local influence (Cook, 1986, Journal of the Royal Statistical Society, Series B 48, 133-169). These authors considered the Diggle and Kenward (1994, Applied Statistics 43, 49-93) model, which is based on a selection model, integrating a linear mixed model for continuous outcomes with logistic regression for dropout. In this article, we show that a similar idea can be developed for multivariate and longitudinal binary data, subject to nonmonotone missingness. We focus on the model proposed by Baker, Rosenberger, and DerSimonian (1992, Statistics in Medicine 11, 643-657). The original model is first extended to allow for (possibly continuous) covariates, whereafter a local influence strategy is developed to support the model-building process. The model is able to deal with nonmonotone missingness but has some limitations as well, stemming from the conditional nature of the model parameters. Some analytical insight is provided into the behavior of the local influence graphs.

Antidepressive Agents, Tricyclic↗
PubMed1999

Memory in coal tits: an alternative model.

Jolliffe and Jolliffe (1997, Biometrics 53, 1136-1142) proposed various models for data from an experiment on memory in coal tits. This article describes an alternative model, which fits equally well and which may be simpler to interpret.

Algorithms↗
PubMed2001

Partial knowledge and answer-until-correct tasks in birds and humans.

Jolliffe and Jolliffe (1997, Biometrics 53, 1136-1142) and Ridout (1999, Biometrics 55, 660-662) have proposed models applicable to memory in coal tits. It is now argued that the birds' task is analogous to answer-until-correct tests used in educational settings in humans, and models from the latter context may be used with the birds' data.

Animals↗
PubMed2004

Modeling the effects of a bidirectional latent predictor from multivariate questionnaire data.

Researchers often measure stress using questionnaire data on the occurrence of potentially stress-inducing life events and the strength of reaction to these events, characterized as negative or positive and assigned an ordinal ranking. In studying the health effects of stress, one needs to obtain measures of an individual's negative and positive stress levels to be used as predictors. Motivated by data of this type, we propose a latent variable model, which is characterized by event-specific negative and positive reaction scores. If the positive reaction score dominates the negative reaction score for an event, then the individual's reported response to that event will be positive, with an ordinal ranking determined by the value of the score. Measures of overall positive and negative stress can be obtained by summing the reactivity scores across the events that occur for an individual. By incorporating these measures as predictors in a regression model and fitting the stress and outcome models jointly using Bayesian methods, inferences can be conducted without the need to assume known weights for the different events. We propose an MCMC algorithm for posterior computation and apply the approach to study the effects of stress on preterm delivery.

Algorithms↗
PubMed2004

Neuropsychological predictors of academic underachievement in pediatric epilepsy: moderating roles of demographic, seizure, and psychosocial variables.

PURPOSE: Academic underachievement is common in pediatric epilepsy. Attempts to identify seizure and psychosocial risk factors for underachievement have yielded inconsistent findings, raising the possibility that seizure and psychosocial variables play a complex role in combination with other variables such as neuropsychological functioning. This study cross-validated a neuropsychological measurement model for childhood epilepsy, examined the relation between neuropsychological functioning and academic achievement, and tested the degree to which demographic, seizure, and psychosocial variables moderate that relation. METHODS: Children with chronic epilepsy (N = 173; ages 8 to 15 years; 49% girls; 91% white/non-Hispanic; 79% one seizure type; 79% taking one medication; 69% with active seizures) completed a comprehensive neuropsychological battery. Children diagnosed with mental retardation were excluded. RESULTS: Structural equation modeling identified a three-factor measurement model of neuropsychological function: Verbal/Memory/Executive (VME), Rapid Naming/Working Memory (RN/WM), and Psychomotor (PM). VME and RN/WM were strongly related to reading, math, and writing; PM predicted writing only. Family environment moderated the impact of neuropsychological deficits on writing (p < or = 0.01) and possibly for reading (p = 0.05); neuropsychological deficits had a smaller impact on achievement for children in supportive/organized homes compared with children in unsupportive/disorganized homes. CONCLUSIONS: These findings lend partial support for our theoretical model showing direct effects of neuropsychological function on achievement and the moderating role of family factors. This study suggests that a subgroup of children with epilepsy (those who have not only neuropsychological deficits but also disorganized/unsupportive home environments) are particularly at risk for adverse academic outcomes. Implications for intervention are discussed.

Adolescent↗