Self-Report Measures of Intelligence: Are They Useful as Proxy IQ Tests?

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.