The linear regression line as a judgmental aid in visual analysis of serially dependent A-B time-series data

The purpose of this study was to investigate the effects of different types and magnitudes of serial dependence (first-order moving average and autoregression) and of linear regression lines within experimental phases on the agreement between results of visual and results of statistical data analyses. The stimulus material consisted of computer-simulated A-B-design data graphs. The time series were generated with a constant variance, varying degrees of treatment effects (changes in level), five conditions of serial dependency, and with or without linear regression lines. The material was presented to three groups of student raters (n₁=52, n₂=14, n₃=17) who rated the treatment effect in the graphs on a five-point scale. These ratings were compared with statistical results (time-series analyses). Each group had to interpret 70 graphs, 35 of which had regression lines. Data were analyzed by means of two three-factor and one four-factor ANOVA and by graphic display. The linear regression lines generally enhanced the agreement between the raters' estimations and the statistical results. Serial dependency also increased the agreement between the two analysis methods. However, with strong autoregression processes in the data, the raters tended to overestimate treatment effects relative to time-series analysis.Parts of this study were presented at the World Congress on Behavior Therapy, Washington, DC, December 11, 1983. The authors wish to express their appreciation to Christoph Bonk and Willi Ecker for their extensive collaboration in data analysis and for their assistance in carrying out the study.     

Expertise and hierarchical knowledge representation in chess

Summary In two experiments the structure of knowledge representation in chess experts and average players was examined. Pattern-recognition theory explains expertise through the existence of many small, unrelated knowledge units. Recent research stresses the structure of knowledge representations. However, the standard paradigm does not allow for the detection of relations between chunks; the theoretical shift has to be accompanied by a methodological shift. In Experiment 1, by means of a partitioning task, evidence was provided for a hierarchical representation of chess positions. Chess masters formed larger and more complex knowledge units than average players. In Experiment 2, the typicality of the positions was varied. The more typical the positions were, the larger and more coherent the constructed knowledge units were. The greatest differences between both groups occurred in more typical positions. This reflects the experts' ability to relate several knowledge units with one another.     

Jury selection in two countries: a psychological perspective

A comparative survey of jury selection practices in Britain and the United States indicates that the two countries differ along a number of dimensions, including the emphasis on the jury selection process in the trial, the amount and type of information available about prospective jurors, and the frequency with which trial lawyers alter the composition of the jury. The probable impact of these differences is analysed by considering the importance of jury composition in determining a jury’s verdict, the effectiveness of lawyers in exercising their challenges, and broader effects of jury selection procedures in the two countries.     

Mitochondrial DNA marker EST00083 is not associated with high vs. average IQ in a German sample

In a recent report in this journal (Plomin & Petrill, 1997), a mitochondrial DNA marker (EST00083) yielded significant associations with high vs. low IQ in two population-based samples of children in the U.S. The present study tested this allelic association for German adults with high vs. average IQ scores. The high IQ adults (N=47) were members of Mensa, an organization whose membership criterion is an IQ score above 130. Their EST00083 allelic frequencies were compared to the allelic frequencies for a control group of adults (N=77) whose IQ scores were less than 110 as estimated from short-term memory and speed-of information-processing tests. Although the differences between the two studies are considerable, the present results do not provide support for the hypothesis that EST00083 is associated with high IQ.     

The perception of foreground and background as derived from structural information theory

Subjects were instructed to order stimuli, consisting of a white and a black part, in accordance with the perceived foreground-strength of the white (or black) part. It appeared that this task can be carried out consistently. The order is explained on the basis of Structural Information Theory. It is argued that this task involves central processes, and that the strength depends on the preference for an interpretation, in which the white (black) part is a foreground on a black (white) background, with respect to the opposed interpretation in which the white (black) part is the background and the black (white) part is foreground.