Wundt as chemist? A fresh look at his practice and theory of experimentation

Mid-19th-century chemistry constituted a practically and theoretically important resource for experimental psychology as conceived by Wilhelm Wundt (1832-1920). In the early 1850s, Wundt began working in Gustav Herth's private chemical laboratory in Heidelberg. The experimental work Wundt conducted under Herth's direction provided the practical model for the psychological methods advocated in Wundt's pioneering publication on visual perception in 1862. With respect to theory, Wundt relied on John Stuart Mill's System of Logic, a book often referring to the chemical writings by Justus Liebig. Wundt not only read and quoted Mill's logic but also was personally acquainted with its German translator, the former Liebig student Jacob Schiel. Thus, in various ways, chemistry influenced Wundt's early theory and practice of experiment.     

Same-sex and cross-sex siblings: Activity choices,roles, behavior,and gender stereotypes

Forty same-sex and cross-sex school-aged sibling pairs were observed in their homes during self-selected activities. The sex role learning index (SERLI) and a sex-typing room analysis were administered for the younger siblings, and maternal questionnaire information was obtained. Sibling gender constellation was associated with reliable differences in activity choices during the unstructured observations. Male dyads interacted less than other sibling groups, while older sisters in female dyads engaged in the most teaching. Older female siblings, regardless of the gender of the younger sibling, assumed the manager role frequently. Dyads containing an older girl also exhibited the greatest role asymmetrics. Affective differences related to gender constellation were also noted. Younger girls with older brothers and younger boys with older sisters evidenced the least gender stereotyping.     

Differential effects of personality traits related to the P-ImpUSS dimension on latent inhibition in healthy female subjects

An experiment was performed to investigate the effects of various personality traits (psychoticism, impulsiveness, sensation seeking) with substantial loadings on the P-ImpUSS dimension on latent inhibition (LI). LI refers to the finding that performance on a learning task is poorer for a preexposed irrelevant stimulus than for a novel stimulus. Forty-eight female subjects were tested by a rule-learning task that has been shown to reliably produce differential LI effects in low and high psychosis-prone normals. Results suggest that, besides psychoticism, the sensation seeking subfactor disinhibition is negatively associated with LI. Furthermore, stepwise regression analysis revealed that combining individual psychoticism and disinhibition scores results in a significant increase in explained variance of LI. These findings are discussed in terms of a relationship between distinct P-ImpUSS-related aspects of personality and LI.     

Estimation of premorbid cognitive function based on word knowledge: the Swedish Lexical Decision Test (SLDT)

In clinical neuropsychology, the present status of a patient is evaluated in relation to the assumed premorbid status. However, in Sweden, existing methods to assess premorbid status are far from optimal. In the present study, the design and evaluation of a Swedish Lexical Decision Test (SLDT) for premorbid global cognitive function (i.e., premorbid intelligence) is described. The design was based on the empirical finding that, in general adult population, word knowledge is strongly associated with measures of global cognitive functioning. Linear stepwise regression analysis demonstrated that SLDT findings accounted for 48% of the variance of global cognitive function as assessed by the Full Scale Intelligence Quotient (FSIQ) from the Wechsler Adult Intelligence Scale Revised (WAIS-R). Demographic variables alone accounted for 31% and a combination of SLDT results and demographics accounted for 60%. Psychometric properties are presented using data from 109 healthy individuals stratified according to age, gender, and level of education. In addition, a case of Alzheimer's disease is presented to illustrate the relationship between SLDT performance and cognitive function. Finally, the theoretical foundation for the relationship between word knowledge and global cognitive function is discussed.     

Aspects of Fluency in Writing

The notion of ‘fluency’ is most often associated with spoken-language phenomena such as stuttering. The present article investigates the relevance of considering fluency in writing. The basic argument for raising this question is empirical—it follows from a focus on difficulties in written and spoken language as manifestations of different problems which should be investigated separately on the basis of their symptoms. Key-logging instruments provide new possibilities for the study of writing. The obvious use of this new technology is to study writing as it unfolds in real time, instead of focusing only on aspects of the end product. A more sophisticated application is to exploit the key-logging instrument in order to test basic assumptions of contemporary theories of spelling. The present study is a dictation task involving words and ‘non-words’, intended to investigate spelling in nine-year-old pupils with regard to their mastery of the doubling of consonants in Norwegian. In this study, we report on differences with regard to temporal measures between a group of strong writers and a group of poor ones. On the basis of these pupils’ writing behavior, the relevance of the concept of ‘fluency’ in writing is highlighted. The interpretation of the results questions basic assumptions of the cognitive hypothesis about spelling; the article concludes by hypothesizing a different conception of spelling.     

R2 effect-size measures for mediation analysis

R ² effect-size measures are presented to assess variance accounted for in mediation models. The measures offer a means to evaluate both component paths and the overall mediated effect in mediation models. Statistical simulation results indicate acceptable bias across varying parameter and sample-size combinations. The measures are applied to a real-world example using data from a team-based health promotion program to improve the nutrition and exercise habits of firefighters. SAS and SPSS computer code are also provided for researchers to compute the measures in their own data.