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.     

Intra-individual variability in task performance after cognitive training is associated with long-term outcomes in children

The potential benefits and mechanistic effects of working memory training (WMT) in children are the subject of much research and debate. We show that after five weeks of school-based, adaptive WMT 6–9 year-old primary school children had greater activity in prefrontal and striatal brain regions, higher task accuracy, and reduced intra-individual variability in response times compared to controls. Using a sequential sampling decision model, we demonstrate that this reduction in intra-individual variability can be explained by changes to the evidence accumulation rates and thresholds. Critically, intra-individual variability is useful in quantifying the immediate impact of cognitive training interventions, being a better predictor of academic skills and well-being 6–12 months after the end of training than task accuracy. Taken together, our results suggest that attention control is the initial mechanism that leads to the long-run benefits from adaptive WMT. Selective and sustained attention abilities may serve as a scaffold for subsequent changes in higher cognitive processes, academic skills, and general well-being. Furthermore, these results highlight that the selection of outcome measures and the timing of the assessments play a crucial role in detecting training efficacy. Thus, evaluating intra-individual variability, during or directly after training could allow for the early tailoring of training interventions in terms of duration or content to maximise their impact.     

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.     

Judging the cross on rings: a matter of achieving shape constancy

The present study examines the influence of viewing position, experience, processing time, and attention on shape constancy in gymnastics judging. In an experiment, 40 gymnastics judges and as many laypeople were presented with a series of photographs that show athletes holding a ‘cross on rings’. They were simultaneously taken from different viewpoints. Participants had to judge how many degrees the arms deviated from horizontal for each picture. One half of the participants had a secondary task, to judge the duration of the picture presentation, which varied also. The overall performances of the gymnastics judges were much better than those of the laypeople, and in contrast to the lay‐judgments, they were not influenced by the secondary task. However, gymnastics judges were still significantly influenced by viewpoint, that is, their error rate increased with an increase in deviation from a frontal view. Copyright © 2005 John Wiley & Sons, Ltd.     

Group size,group status and trait valence as determinants of intergroup bias: Stereotyping in Finland and Sweden

The effects of group size, group status and trait valence (positive or negative stereotypes of in‐ and outgroup) on intergroup bias was studied in nation‐wide probability samples of majority and minority groups in Finland and Sweden, (N = 2479). Ethnolinguistic vitality was used as a proxy for status. It is argued that the specific history of real‐life intergroup relations has to be duly acknowledged when predicting main and interactive effects on intergroup bias in natural contexts. Supporting the predictions made, numerical group size showed a stable main effect; members of numerical minorities showed more bias than members of numerical majorities, regardless of trait valence. While status had no main effect, there was a significant interaction between status and size as well as between status and trait valence: intergroup bias was highest in the high status minority, and low status groups showed less bias than high status groups on negatively valenced traits. In fact, minority members showed the reverse of PNAE. In addition, majority members favoured the outgroup on negatively valenced traits, but favoured their ingroup on positively valenced traits. Different explanations for these results are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Early activity in the lateralized readiness potential suggests prime-response retrieval as a source of negative priming

Negative priming (NP) refers to increased response time (RT) for a probe target that was a distractor in a preceding prime presentation (distractor-target shift, DT), compared to novel targets. The present study used the lateralized readiness potential (LRP) to investigate, in a four-choice identification task, a novel episodic-retrieval explanation of NP introduced by Rothermund, Wentura, and de Houwer (2005). This theory proposes that retrieval reactivates the prime response which interferes with selection of the correct probe response, thereby producing NP. 20 participants responded to pairs of red and blue digits, contingent on the identity of the digit presented in the target color. Behavioral NP involved RT increase by 16 ms. With shift trials (different hands used for prime and probe responses), in the DT condition LRP onset was delayed relative to control. By contrast, earlier LRP onset was observed for DT relative to control with no-shift trials (same hand used for prime and probe responses). Behavioral NP effects showed similar magnitude for shift and no-shift trials. Results support the Rothermund et al. (2005) theory of prime-response retrieval.