Relative Necessity Reformulated

This paper discusses some serious difficulties for what we shall call the standard account of various kinds of relative necessity, according to which any given kind of relative necessity may be defined by a strict conditional - necessarily, if C then p - where C is a suitable constant proposition, such as a conjunction of physical laws. We argue, with the help of Humberstone (Reports on Mathematical Logic, 31, 33–421, 1981), that the standard account has several unpalatable consequences. We argue that Humberstone’s alternative account has certain disadvantages, and offer another - considerably simpler - solution.     

Tridimensional personality traits of college student marijuana users

The present study examined the possibility that marijuana use among college students might be associated with particular personality traits. College student volunteers (N = 176) were administered the Tridimensional Personality Questionnaire and a drug-use questionnaire. Analysis of variance showed that the mean score on Novelty Seeking was significantly higher and on Persistence significantly lower among lifetime marijuana users than among nonmarijuana using peers. Programs for prevention among college students may be enhanced by approaches tailored to individuals scoring high on Novelty Seeking and low on Persistence.     

Analysis of group differences in processing speed: Brinley plots,Q-Q plots,and other conspiracies

Researchers in a growing number of areas (including cognitive development, aging, and neuropsychology) use Brinley plots to compare the processing speed of different groups. Ratcliff, Spieler, and McKoon (2000) argued that a Brinley plot is a quantile-quantile (Q-Q) plot and that therefore Brinley plot regression slopes measure standard deviation ratios rather than relative speed of processing. We show that this argument is incorrect. Brinley plots, by definition, are not Q-Q plots; the former are based on unranked data and the latter are based on ranked data. Furthermore, the relationship between standard deviation ratios and slopes is a general property of regression lines and has no implications for the use of Brinley plot regression slopes as processing speed measures. We also show that the relative speed interpretation of Brinley plot slopes is strongly supported by converging evidence from a metaanalysis of visual search, mental rotation, and memory scanning in young and older adults. As to Ratcliff et al.'s hypothesis that age differences in response time are attributable to greater cautiousness on the part of the elderly, rather than true processing speed differences, this hypothesis has been extensively tested in previous studies and found wanting.     

Age and individual differences in visuospatial processing speed: Testing the magnification hypothesis

Forty young adults and 40 older adults performed seven visuospatial information processing tasks. Factor analyses of the response times (RTs) yielded a single principal component with a similar composition in both age samples. For both samples, regressing the mean RTs of fast and slow subgroups for the seven tasks (18 conditions) on the corresponding mean RTs for their age group accounted for 99% of the variance. Taken together, these findings suggest that individual differences in processing time were largely task independent. The magnification hypothesis, a simple mathematical model of the interaction between age and ability, is presented. This model correctly predicts the finding that in both the young and the older adult groups, individual differences increased systematically with task difficulty. The magnification hypothesis also explains the regression parameters describing individual differences among young adults and predicts correctly that equivalent parameters describe individual differences among older adults. According to the magnification hypothesis, the RTs of slower individuals are more affected by aging than those of faster individuals, and slower individuals may be more at risk with respect to other biological insults (e.g., changes in health status) as well.     

The Influence of Efficacy Beliefs on Teacher Performance and Student Success: Implications for Student Support Services

The influence of teachers’ efficacy beliefs on student achievement is well documented in educational literature. Efficacy beliefs are derived from sources of information teachers obtain from professional experiences. This article provides student support services personnel with an overview of efficacy beliefs and their impact on teachers’ thoughts, emotions, and behaviors. A cognitive behavioral framework, rational emotive behavior therapy, is used to conceptualize ways efficacy beliefs may hinder teacher performance and student success. Implications for student support services and research are provided.