Line bisecting as a predictor of personal optimism and desirability of risky behaviors.

Our goal was to test whether current hemisphere predominance is a predictor of scores on standardized measures of personal optimism and preference for risk. In two between-subject experiments, current hemisphere predominance was measured by the direction and extent of line bisecting errors. Pearson correlations and median splits of the line bisecting errors showed significantly greater personal optimism and preference for risk with left hemisphere predominance. These results support previous research in which manipulation of hemisphere predominance produced similar effects on personal optimism in normal individuals and on risk taking in lesioned and normal samples. We conclude that the association of optimism and risk with left hemisphere predominance can be observed in resting as well as in manipulated situations.     

Lateral asymmetry of personal optimism

By combining models of cerebral emotional asymmetry and unilateral hemispheric activation, it was hypothesized that orienting to the right would produce greater personal optimism about future events than would orienting toward the left. This was supported significantly in two experiments which differed from each other in their manipulations, hypothetical future events, means of responding, and settings. The results supported previous research on unrealistic optimism and extended the concept to show the effect of induced lateral orientation. It was proposed that this effect is mediated by mood, and possibly by perceived control, and that this methodology can be extended to other behaviors which have proven amenable to mood manipulation.     

Statistical simulation on microcomputers

The statistical simulation program DATASIM is designed to conduct large-scale sampling experiments on microcomputers. Monte Carlo procedures are used to investigate the Type I and Type II error rates for statistical tests when one or more assumptions are systematically violated-assumptions, for example, regarding normality, homogeneity of variance or covariance, mini-mum expected cell frequencies, and the like. In the present paper, we report several initial tests of the data-generating algorithms employed by DATASIM. The results indicate that the uniform and standard normal deviate generators perform satisfactorily. Furthermore, Kolmogorov-Smirnov tests show that the sampling distributions ofz, t, F, χ², andr generated by DATASIM simulations follow the appropriate theoretical distributions. Finally, estimates of Type I error rates obtained by DATASIM under various patterns of violations of assumptions are in close agreement with the results of previous analytical and empirical studies; These converging lines of evidence suggest that DATASIM may well prove to be a reliable and productive tool for conducting statistical simulation research.     

Tempo discrimination in infants

An habituation/dishabituation paradigm demonstrates that 2- and 4-month-old infants are able to discriminate auditory sequences that vary slightly in tempo. Discriminations were only observed for intermediate tempi (600 ms but not 100, 300, 1500 ms IOI), suggesting that infants have the same optimal tempo range as adults.     

Homelessness and dual diagnosis.

People who are dually diagnosed with severe mental illness and substance use disorders constitute 10%-20% of homeless persons. They are a heterogeneous and extremely vulnerable subgroup with complex, poorly understood needs. In this article recent research on the epidemiology, subject characteristics, and service needs of the dually diagnosed homeless population is reviewed. Also, the range of evolving approaches to providing social services, housing, and mental health and substance-abuse treatments; the relevant system issues and legal issues; and problems with current research, as well as future research directions, are discussed. The importance of the distinction between providing appropriate living environments and mental health treatments emerges throughout.     

Processing persuasive arguments: recall and recognition as a function of agreement and manipulated activation asymmetry

Previous research has demonstrated greater attention toward disagree arguments and a greater persuasibility during relative right than during relative left hemisphere activation. This experiment was performed to conceptually replicate and extend these findings to memory stages in the processing of persuasive arguments. The experiment used induction of lateral orientation of attention as the means to selectively activate regions of the brain in normal right-handed subjects. The results showed the expected significant interaction for correct recall as a function of agreement with the argument and hemisphere activated. There was greater recall of agree arguments during left hemisphere activation and greater recall of disagree arguments during right hemisphere activation, as predicted. The effect for recognition memory was in the same direction, but was statistically nonsignificant. These findings support previous research on cerebral asymmetries in the processing of persuasive arguments. This phenomenon is discussed as a possible outcome of asymmetries of affect.     

Anatomy of a DATASIM simulation: The Doob and Gross horn-honking study

The program DATASIM is used to simulate the classic “horn-honking” study by Doob and Gross (1968). In a 2×2 field experiment, Doob and Gross investigated the effects of status of frustrator—a low- or high-status car blocking an intersection—on the latency to honk among male and female drivers. The present paper illustrates how to extract the values of simulation parameters from the published study, how to initialize the simulation in DATASIM, and how to generate and analyze the simulated data. Certain complications arise because the latency data collected by Doob and Gross were nonnormally distributed, cell variances were heterogeneous, and sample sizes were unequal. DATASIM is able to incorporate these features in the simulation, and several methods for assessing the quality of the simulation are illustrated. In addition, sampling experiments are reported, which were performed to assess the joint and individual effects of nonnormality and heterogeneity on the Type I and Type II error rates of theF test. The paper concludes with some practical suggestions regarding how researchers can evaluate, and adjust for, the effects of such violations.     

Bisecting and behavior: lateral inattention predicts 8-week academic performance

Converging evidence supports a left hemisphere role in defensive repression and sensation seeking. This led to the hypothesis that students with a relatively active left hemisphere would perform poorly during 8 weeks of a college class. The measure of relative hemispheric activation was the visual line-bisecting task given early in the course. The hypothesis was supported. Previous evidence that activation asymmetry is stable over time was supported because the single measurement of line bisecting was a longitudinal predictor of multiple behaviors. A temporal pattern of increasing correlation between the bisecting and performance measures favors a feedback repression model. Alternative explanations based on sensation seeking, subject-matter repression, and cooperation were considered but not eliminated.