Over-claiming is a concrete operalization of self-enhancement based on respondents' ratings of their knowledge of various persons, events, products, and so on. Because 20% of the items are nonexistent, responses can be analyzed with signal detection formulas to index both response bias (over-claiming) and accuracy (knowledge). Study 1 demonstrated convergence of over-claiming with alternative measures of self-enhancement but independence from cognitive ability. In Studies 2-3, the validity of the overclaiming index held even when respondents were (a) warned about the foils or (b) asked to fake good. Study 3 also showed the utility of the over-claiming index for diagnosing faking. In Study 4, the over-claiming technique was applied to the debate over the adaptive value of positive illusions.

Correlations between single-item self-reports of intelligence and IQ scores are rather low (.20-.25) in college samples. The literature suggested that self-reports could be improved by three strategies: (1) aggregation, (2) item weighting, and (3) use of indirect, rather than direct, questions. To evaluate these strategies, we compared the validity of aggregated and unaggregated versions of direct measures with four indirect measures (Gough's Intellectual efficiency scale, Hogan's Intellect composite scale, Sternberg's Behavior Check List, and Trapnell's Smart scale). All measures were administered to two large samples of undergraduates (Ns = 310, 326), who also took an IQ test. Although results showed some success for both direct and indirect measures, the failure of their validities to exceed .30 impugns their utility as IQ proxies in competitive college samples. The content of the most valid items referred to global mental abilities or reading involvement. Aggregation benefited indirect more than direct measures, but prototype-weighting contributed little.

Background:The decline in physical activity during adolescence is a key public health concern. This comparative study assesses whether the age-related decline in physical activity among high school students occurs similarly in the United States (US) and Ontario, whether the decline in physical activity is steady throughout the age range, or whether any declines are age-specific.Methods: Data are based on self-reports of 9 th -to 12 th -graders derived from the 2001 Youth Risk Behavior Survey (n=13,503) and the 2001 Ontario Student Drug Use Survey (n=1,322). Physical activity is measured by the number of days of vigorous physical activity during the past 7 days. Results:In both samples, there was a dominant and steady decline in physical activity between ages 14 and 18 years. The number of activity days was higher in the US than in Ontario holding constant age and sex. However, a significant sample-by-age interaction showed that the decline in the percentage of US students reporting 3 or more physical activity days was greater than it was in Ontario.Conclusions: While the pattern of decline was shown to be similar, the decline was stronger among US adolescents. Future research should examine additional factors influencing the decline in activity and the optimal timing of programs to reduce the decline.

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This paper describes a revised measure of self-efficacy to overcome barriers to moderate and vigorous physical activity in a sample of 484 high school students in Toronto, Ontario. The students had a mean age of 15.3 years. Principal axis factoring with oblique rotation yielded five factors: self-efficacy to overcome internal, harassment, physical environment, social environment, and responsibilities barriers. Two problematic items were removed, which resulted in a 22-item measure. Subsequent analyses were conducted on responses to this shortened measure. Confirmatory factor analysis supported the five-factor model and demonstrated age- and sex-invariance. The subscales had good internal consistency reliability. Structural regressions demonstrated a strong relationship between the resulting factors and a physical activity measure (energy expenditure), showing predictive validity.