Does decision quality (always) increase with the size of information samples? Some vicissitudes in applying the law of large numbers

Adaptive decision making requires that contingencies between decision options and their relative assets be assessed accurately and quickly. The present research addresses the challenging notion that contingencies may be more visible from small than from large samples of observations. An algorithmic account for such a seemingly paradoxical effect is offered within a satisficing-choice framework. Accordingly, a choice is only made when the sample contingency describing the relative evaluation of the 2 options exceeds a critical threshold. Small samples, because of the high dispersion of their sampling distribution, facilitate above-threshold contingencies. Across a broad range of parameters, the resulting small-sample advantage in terms of hits is stronger than their disadvantage in false alarms. Computer simulations and experiments support the model predictions. The relative advantage of small samples is most apparent when information loss is low, when the threshold is high relative to the ecological contingency, and when the sampling process is self-truncated.     

The effect of caffeine on handwriting movements in skilled writers

In laboratory tasks, caffeine has been shown to improve psychomotor performance. The aim of the present experiment was to assess the effects of caffeine on a skilled everyday life task in habitual caffeine consumers. The assessment of handwriting movements of 20 adults was performed following the administration of 0mg/kg (placebo), 1.5mg/kg, 3.0mg/kg or 4.5mg/kg of caffeine. A digitising tablet was used for the assessment of fine motor movements. Participants were asked to perform a simple writing task. Kinematic analysis of handwriting movements showed that, in comparison to placebo administration, high doses of caffeine (i.e., 4.5mg/kg) can produce improvements in handwriting as indicated by more fluent handwriting movements as well as an increase in maximum velocity and maximum positive and negative accelerations. The results suggest that higher doses of caffeine can enhance psychomotor performance.     

On the development of the mental number line: more, less, or never holistic with increasing age?

Magnitude is assumed to be represented along a holistic mental number line in adults. However, the authors recently observed a unit-decade compatibility effect for 2-digit numbers that is inconsistent with this "holisticness" assumption (H.-C. Nuerk, U. Weger, & K. Willmes, 2001). This study used the compatibility effect to examine whether the mental number line representation of magnitude changes toward greater or less holisticness in children from Grades 2-5. The results indicate that decades and units of 2-digit numbers are processed separately rather than holistically from Grade 2 on. However, this separate processing seems to develop from a more sequential (left-to-right) to a more parallel processing mode. Moreover, children may use different strategies depending on task demands. The results are interpreted in the framework of Siegler's overlapping waves model.     

The effect of conscious control on handwriting in children with attention deficit hyperactivity disorder

Two experiments were performed regarding the effect of conscious control on handwriting fluency in healthy adults and ADHD children. First, 26 healthy students were asked to write a sentence under different conditions. The results indicate that automated handwriting movements are independent from visual feedback. Second, the writing performance of 12 children with ADHD was examined on their usual medication with methylphenidate and under placebo. In comparison to placebo, medication with methylphenidate resulted in a reduced fluency of handwriting. Automated handwriting movements could be elicited in children with ADHD on medication. The results suggest that both visual and mental control of handwriting movements affect the automation of handwriting movements. Furthermore, a simple training procedure was designed and performed in a case study of a boy with ADHD.     

Limitations of the dual-process-theory regarding the writing of words and non-words to dictation

It is generally assumed that the lexical and phonological systems are involved in writing to dictation. In an experiment concerned with the writing of words and non-words to dictation, the handwriting of female students was registered using a digitising tablet. The data contradict the assumption that the phonological system represents an alexical process. Both words and non-words which were acoustically presented to the subjects were lexically parsed. The analysis of kinematic data revealed significant differences between the subjects' writing of words and non-words. The findings reveal gross disturbances of handwriting fluency during the writing of non-words. The findings of the experiment cannot be explained by the dual-process-theory.     

Valence of distractor words increases the effects of irrelevant speech on serial recall

Participants memorized target words in silence or while ignoring neutral or valent (positive or negative) distractor words that could be either possessor-relevant or other-relevant. Distractor words impaired recall performance, but valent distractor words caused more disruption than neutral distractors, and negative distractors caused more disruption than positive distractors. The results are problematic for explanations of the irrelevant speech effect within working memory models that do not specify an explicit role of attention in the maintenance of information for immediate serial recall.     

Mood and flexibility in categorization: a conceptual replication

The present study tested the hypothesis that positive mood facilitates cognitive flexibility in categorization, i.e., positive mood enhances the ability to categorize flexibly at broad and narrow levels contingent on task requirement. The study was a conceptual replication of the 1990 work by Murray, Sujan, Hirt, and Sujan. Unlike the original study, it was carried out on the WWW with some modifications in the procedure. Participants were 29 women and 132 men whose average age was 29 yr. They were put into a positive, negative, or neutral mood using the Velten technique. Mood was measured with standard mood scales. Subjects then listed similarities differences between two entertainment TV shows. Contrary to the prediction, participants in a positive mood did not list a higher number, more diverse, or more unusual similarities and differences between the shows, and they were not faster than participants with neutral or negative moods. It is concluded that the influence of mood on cognitive flexibility needs to be reconsidered. In research, temporal aspects of categorization performance as well as a wider range of mood valences should be taken into account.     

Konzeptualisierung in inkrementell-integrativer Sprachverarbeitung

Conceptualization in incremental-integrative\hb language processing Summary. Language is a versatile instrument in co-operatively solving a construction task. In order to understand instructions given during such a task, objects have to be identified and the type of action to be performed has to be determined. The experiments presented show that the way in which objects and actions are conceptualized depends on the linguistic and the non-linguistic, visually available context. Both kinds of information are processed incrementally in an integrative way. The impact of relevant factors, such as the specificity of verbs and object namings, object properties such as color, size, location and the dynamically determined class to which the object belongs was studied. Conclusions for models of language understanding and language production are drawn and requirements for a grammatical formalism suitable for incremental and integrative processing are formulated. Zusammenfassung. Sprache ist ein wichtiges Instrument bei der kooperativen Lösung einer Konstruktionsaufgabe. Zum Verstehen von Handlungsanweisungen im Rahmen dieser Aufgabe müssen Objekte identifiziert und die Art der Handlung erkannt werden. Es werden empirische Untersuchungen vorgestellt, die zeigen, daß die Konzeptualisierung der Objekte und Handlungen vom sprachlichen und nichtsprachlichen, visuell verfügbaren Kontext abhängt. Beide Arten von Kontextinformation werden inkrementell und integrativ verarbeitet. Dazu wurde der Einfluß einzelner Faktoren wie die Spezifität von Verben und Objektbezeichnungen, Objekteigenschaften wie Farbe, Größe und Position sowie die dynamisch zugewiesene Objektklasse und die Wortstellung der benutzten Sprache untersucht. Es werden Folgerungen für die Modellierung von beiden Richtungen der Sprachverarbeitung, Rezeption und Produktion, gezogen und Anforderungen an einen Grammatikformalismus zur inkrementell-integrativen Satzverarbeitung dargestellt.     

Vocal cues in emotion encoding and decoding

This research examines the correspondence between theoretical predictions on vocal expression patterns in naturally occurring emotions (as based on the component process theory of emotion; Scherer, 1986) and empirical data on the acoustic characteristics of actors' portrayals. Two male and two female professional radio actors portrayed anger, sadness, joy, fear, and disgust based on realistic scenarios of emotion-eliciting events. A series of judgment studies was conducted to assess the degree to which judges are able to recognize the intended emotion expressions. Disgust was relatively poorly recognized; average recognition accuracy for the other emotions attained 62.8% across studies. A set of portrayals reaching a satisfactory level of recognition accuracy underwent digital acoustic analysis. The results for the acoustic parameters extracted from the speech signal show a number of significant differences between emotions, generally confirming the theoretical predictions.This research was supported by a grant from the Deutsche Forschungsgemeinschaft (Sche 156/8-5). The authors acknowledge collaboration of Westdeutscher Rundfunk, Cologne, in producing professional versions of actor emotion portrayals, and thank Kurt Balser, Theodor Gehm, Christoph Gierschner, Judy Hall, Ursula Hess, Alice Isen, and one anonymous reviewer for helpful comments and contributions.