The temporal selectivity of additive factor effects on the reaction process revealed in ERP component latencies

An experiment was conducted to relate individual components of the event-related brain potential to specific stages of information processing in a two-choice reaction time (RT) task in a group of undergraduate students. Specifically, the latency of the P300 component and the lateralized readiness potential (LRP) were studied as a function of variations in stimulus degradation and response complexity. It was hypothesized that degrading the stimulus would delay the P300 and LRP to the same extent as RT, and that increasing response complexity would affect RT but not P300 latency. The extant literature did not permit any hypothesis regarding the effect of response complexity on LRP latency. The two task variables were found to have additive effects on RT. As predicted, variations in stimulus degradation influenced the latencies of both components, whereas alterations in response complexity had no effect on P300 latency. A significant new finding was that the onset latency of the LRP remained unchanged across levels of response complexity. The overall pattern of results supports the notion of temporal selectivity of stage manipulations that is derived from discrete stage models of human information processing. Furthermore, these results refine the functional interpretation of the LRP by indicating that within the conceptual framework of a stage model the processes this component indexes succeed the start of response choice but precede the start of motor programming.     

Depression in children: Parent,teacher, and child perspectives

Depressed and nondepressed children were found to differ in the types of behavior problems manifested at home and at school. Children rated as depressed by their parents on the Personality Inventory for Children evidenced significantly more conduct problems, anxiety, impulsive hyperactivity, learning problems, psychosomatic problems, perfectionism, and muscular tension at home than children rated as nondepressed. Depressed children were rated by their teachers as displaying more inattentionpassivity than nondepressed children. A significant but modest relationship was found between parent report and child selfreport of the child's depression. Depressed children attributed positive events to external causes and negative events to internal causes significantly more than did nondepressed children. The specificity of these results to depression was also examined;the particular features of childhood depression are compared to the features of adult depression. The investigators would like to thank Jim McFerren and Ralph Zalazar for their work as research assistants and David Watson for his help with the statistical analyses. The helpful comments of Eric Klinger and Auke Tellegen are gratefully acknowledged. The cooperation of Dr. Loren Benson, director of personnel services of the Hopkins School District #274; Mr. Edward Ryshavy, principal of Glen Lake Elementary School; and the teachers of that school is greatly appreciated.     

The effect of set size on hemifield asymmetries in letter recognition

Single letters were presented tachistoscopically in the left or right hemifield to right-handed observers. Superior recognition of letters on the right was found for letters chosen from subsets containing four items, but no differences were found when any letter, or any symmetrical letter, could appear. In a second experiment, the right hemifield advantage was found under conditions requiring the subject to determine the subset only when the subset chosen was appropriate. Results were discussed in terms of the adequacy of language-based explanations of hemifield asymmetries in letter recognition.     

Gender differences in tobacco use

Gender differences in overall tobacco use clearly exist. In general, men are more likely to use tobacco products than are women. However, this simple generalization, ignoring type of tobacco products, time, and culture, masks many more interesting gender differences in tobacco use. There are pronounced gender differences in tobacco use of specific tobacco products within some cultures but not others. Yet these differences have changed across time, including narrowing and widening of this gender gap, depending on culture and tobacco product. This article addresses these issues and presents possible psychosocial, biological, and psychobiological explanations for these phenomena. In addition, the implications of these differences and ways to learn more about these important differences are discussed.     

Emotional Reactions to News Events1

This study was designed to determine (a) what dimensions underlie emotional reactions to news events, (b) whether these dimensions are independent, (c) whether reactions to major news events are similar for different groups of people, and (d) whether a simple method could be developed for evaluating emotional reactions to news events. Subjects rated the similarity of their emotional reactions to 20 page-one newspaper stories in a paired-comparison task. The data were multidimensionally scaled using the KYST computer program. Two dimensions emerged that accounted for 89% of the judgment variance: pleasure/displeasure and degree of arousal. Interpretation of these dimensions was verified using a semantic differential task. The two dimensions were not independent. They were related by a U-shaped function: News events farther from evaluative neutrality were judged more arousing. A second study with 40 news events and a different subject population replicated these findings. Subjects' ratings of news events on three scales (happy, important, and exciting) were sufficient to recover the KYST dimensions. The theoretical and practical implications of these. results are discussed.     

The effect of landmark features on mental rotation times

By varying what we take to be the saliency oflandmarks (which are cues to location and orientation that are unique and visible from a distance), the slopes and intercepts of the time/angle function in the "mental rotation" task were caused to vary accordingly.     

Reaction time, race, and racism

The claim (Jensen, 1975) that blacks are slower than whites in choice (but not simple) reaction time is examined. It is false. The claim (Jensen, 1985) that Muhammad Ali was shown to have a “very average” reaction time is examined. It is false. The claim (Vernon & Jensen, 1984) that an unpublished technical report showed blacks to be inferior to whites on a relatively content-free mental processing task is examined. It is false. Suggestions are made concerning relevant questions that might be addressed by students of race differences in intelligence.