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Null sex differences in general intelligence: evidence from the WAIS-III
Roberto Colom1, Luis F García, Manuel Juan-Espinosa
1Facultad de Psicología, Universiad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain. roberto.colom@uam.es
The Spanish Journal of Psychology
|May 25, 2002
Summary
Sex differences in intelligence are debated. While males show a slight advantage in general ability scores, this is not present in general intelligence (g), suggesting specific test factors, not true cognitive differences.
Area of Science:
- Psychometrics
- Cognitive Psychology
- Sex Differences Research
Background:
- Ongoing debate regarding the existence and nature of sex differences in general intelligence.
- Empirical claims often rely on summed cognitive test differences, which may not reflect the scientific construct of general intelligence (g).
- General intelligence (g) is defined by correlations among diverse cognitive tests, not by summation of scores.
Purpose of the Study:
- To investigate potential sex differences in general intelligence (g) versus "ability in general" using a large, representative Spanish sample.
- To analyze the Spanish standardization data of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III).
- To clarify the construct validity of observed IQ sex differences.
Main Methods:
- Analysis of the Spanish WAIS-III standardization sample (N=1369; 703 females, 666 males, aged 15-94).
- Examination of sex differences in overall IQ scores.
- Distinguishing between "general ability" (summation of scores) and "general intelligence" (g, based on correlations).
Main Results:
- A statistically significant male advantage of 3.6 IQ points was observed in "ability in general."
- No significant sex difference was found in the underlying general intelligence factor (g).
- The observed male advantage in IQ is attributable to specific group factors and test specificity, not general intelligence.
Conclusions:
- The average sex difference in IQ scores favoring males is not indicative of a difference in general intelligence (g).
- The construct of general intelligence (g) is invariant across sexes in this sample.
- Observed IQ differences are likely influenced by specific cognitive abilities or test characteristics rather than fundamental differences in general cognitive ability.