Hick’s law equivalent for reaction time to individual stimuli

Hick’s law, one of the few law-like relationships involving human performance, expresses choice reaction time as a linear function of the mutual information between the stimulus and response events. However, since this law was first proposed in 1952, its validity has been challenged by the fact that it only holds for the overall reaction time (RT) across all the stimuli, and does not hold for the reaction time (RT_i) for each individual stimulus. This paper introduces a new formulation in which RT_i is a linear function of (1) the mutual information between the event that stimulus i occurs and the set of all potential response events and (2) the overall mutual information for all stimuli and responses. Then Hick’s law for RT follows as the weighted mean of each side of the RT_i equation using the stimulus probabilities as the weights. The new RT_i equation incorporates the important speed–accuracy trade-off characteristic. When the performance is error-free, RT_i becomes a linear function of two entropies as measures of stimulus uncertainty or unexpectancy. Reanalysis of empirical data from a variety of sources provide support for the new law-like relationship.     

Is dispositional optimism or dispositional pessimism predictive of ideal cardiovascular health? The Young Finns Study

Objective: We examined the independent association between dispositional optimism compared to dispositional pessimism and ideal cardiovascular health (defined by the American Heart Association).

Design: A prospective design with a study sample of 1113 participants aged 24–39 years from the longitudinal Young Finns Study.

Main outcome measures: Ideal cardiovascular health (comprised of seven ideal cardiovascular health metrics) was measured in 2001. The ideal cardiovascular health metrics were reassessed in 2007.

Results: Low pessimism rather than high optimism was a better predictor of ideal cardiovascular health in 2007. When examining the association between optimism and pessimism and the seven ideal cardiovascular health metrics in 2007 (BMI, diet, physical activity, smoking status, blood pressure, total cholesterol and plasma glucose), low pessimism predicted non-smoking status, ideal physical activity and eating a healthy diet, while high optimism was associated with eating a healthy diet.

Conclusion: Our findings suggest that low pessimism rather than high optimism is associated with ideal cardiovascular health, especially with health behaviours such as not smoking, being physically active and eating a healthy diet. Socio-economic status was the potential mediating or confounding factor. Future studies should examine the differential meaning of the optimism/pessimism concepts to further clarify their relation to health outcomes.     

Correcting Too Much or Too Little? The Performance of Three Chi-Square Corrections

This simulation study investigates the performance of three test statistics, T₁, T₂, and T₃, used to evaluate structural equation model fit under non normal data conditions. T₁ is the well-known mean-adjusted statistic of Satorra and Bentler. T₂ is the mean-and-variance adjusted statistic of Sattertwaithe type where the degrees of freedom is manipulated. T₃ is a recently proposed version of T₂ that does not manipulate degrees of freedom. Discrepancies between these statistics and their nominal chi-square distribution in terms of errors of Type I and Type II are investigated. All statistics are shown to be sensitive to increasing kurtosis in the data, with Type I error rates often far off the nominal level. Under excess kurtosis true models are generally over-rejected by T₁ and under-rejected by T₂ and T₃, which have similar performance in all conditions. Under misspecification there is a loss of power with increasing kurtosis, especially for T₂ and T₃. The coefficient of variation of the nonzero eigenvalues of a certain matrix is shown to be a reliable indicator for the adequacy of these statistics.     

Occupational Therapists' Experience Concerning Occupational Performance in Adults With Asperger Syndrome

Persons with Asperger Syndrome often seem to have difficulty performing everyday occupations. This study aimed to describe occupational therapists' experience concerning abilities to occupational performance among adults with Asperger Syndrome. Data were collected in interviews with eight occupational therapists and analyzed using a qualitative method. Results showed that clients with Asperger Syndrome often possess abilities but seem to have difficulties knowing when, where, and how they should use them. The ability to adapt behavior in accordance with cues from the environment was identified as the core category. Environment plays a major role in how these persons interact in different situations.     

Effects of Personal Epistemology on the Understanding of Multiple Texts

We examined whether the text understanding of students holding naïve and sophisticated epistemological beliefs was differentially affected by text format, also controlling for effects of gender, word decoding, and prior knowledge on understanding. The participants were 39 Norwegian first-year teacher students, and the topic of reading was attention-deficit hyperactivity disorder (ADHD). It was found that only readers holding sophisticated epistemological beliefs displayed adequate understanding when reading multiple, partly conflicting, texts about ADHD, whereas students holding naïve epistemological beliefs gained better understanding when reading a single textbook-like source with identical content. This finding, however, depended on the level of understanding being measured by the criterial task, with only the task measuring deeper situational text understanding showing an interaction between epistemological beliefs and text format. This study provides evidence that not only knowledge itself, but also personal beliefs about knowledge, may enhance or constrain deeper understanding of multiple texts.     

DSM-IV-Defined Inattention and Sluggish Cognitive Tempo: Independent and Interactive Relations to Neuropsychological Factors and Comorbidity

The aim of the present study was to investigate the independent relations of DSM-IV-defined inattention and behaviors characteristic of sluggish cognitive tempo (SCT) to neuropsychological factors and problem behaviors often comorbid with attention deficit/hyperactivity disorder (ADHD). By controlling for symptoms of DSM-IV-defined inattention, unique relations to SCT could be ascertained. Additionally, interactive relations of DSM-IV-defined inattention and SCT were of interest. A community-based sample of school children (N = 209; the higher end of the ADHD-symptom range was oversampled) completed neuropsychological tasks designed to measure executive function (EF), sustained attention, and state regulation. Behavioral symptoms were measured using parental and teacher ratings of the DSM-IV criteria for ADHD and Oppositional Defiant Disorder (ODD). The results showed that these two domains of inattention, DSM-IV-defined inattention and SCT, have neuropsychological processes and comorbid behavioral problems in common. However, when controlling for the overlap, DSM-IV-defined inattention was uniquely related to EF and state regulation, while SCT was uniquely related to sustained attention. In addition, the results showed an interactive relation of DSM-IV-defined inattention and SCT to ODD. Findings from the present study support the notion that DSM-IV-defined inattention constitutes a somewhat heterogeneous condition. Such results can further our theoretical understanding of the neuropsychological impairments and comorbid behavioral problems associated with ADHD symptoms.     

Bullying in Danish work-life: Prevalence and health correlates

Given the pioneering role of Scandinavian research in the field of bullying at work, it is surprising that Danish researchers have largely ignored this problem. Presumably, this has led to a situation where many Danish company managers and unions ignore the high individual and organizational costs of workplace bullying. An additional effect of this lack of research is that it has been difficult to estimate the extent to which the prevalence of bullying varies in different sectors of Danish work-life. Furthermore, the scarcity of research has impeded us from determining whether a low prevalence of bullying is a general characteristic of Scandinavian work-life as indicated by previous Swedish and Norwegian studies. Yet again, making such between-nations comparisons in the prevalence of workplace bullying is difficult given the tendency amongst researchers to employ different ways of measuring bullying. The aims of the present study were: (1) to assess the prevalence of bullying in Danish work-life; (2) to investigate if exposure to bullying behaviours at work is related to self-reported psychological and psychosomatic stress symptoms; (3) to examine potential differences in the prevalence of bullying in various work sectors; (4) to explore the hypothesis that, generally, Scandinavian work-life is characterized by low levels of bullying; and (5) to investigate the extent to which using different criteria for assessing bullying results in disparate prevalence estimates. Results showed that 2-4% of the respondents reported being victims of bullying, in most cases only occasionally. Compared to self-reported bullying, prevalence levels based on an operational definition of bullying (i.e., weekly exposure to one act for at least 6 months) were higher in all the samples, between 8% and 25%. When using a more strict criterion of two acts a week, these figures were significantly reduced. Exposure to bullying was found to be associated with increased self-reported strain reactions.