The influence of personality on three aspects of cognitive performance: processing speed, intelligence and school performance

According to the mental speed approach, measures of speed of information processing represent cognitive ability in a comparatively ‘pure’ form, i.e. less influenced by cultural and learning factors than psychometric intelligence tests. In contrast school performance is assumed to be strongly influenced by cultural and personality factors like motivation, diligence, relationship to teachers etc. Former research has shown, that the speed-intelligence relationship cannot be explained by higher cognitive processes like motivation. But no research has simultaneously investigated the impact of personality on processing speed measures, psychometric intelligence test scores and school performance in comparison. The more ‘culture fair’ processing speed tests should be less influenced by personality. To test this hypothesis, stepwise regressions between personality scales and different processing speed measures (Zahlen-Verbindungs-Test, Coding Test), psychometric intelligence tests (Kognitiver Fähigkeits-Test, Advanced Progressive Matrices) and school performance (grades) were calculated. In a sample of 280 students from German gymnasiums (class-levels 9 and 10) results show a weak multiple correlation of personality with processing speed (R=0.32), a medium correlation with intelligence (R=0.51) and a high correlation with grades (R=0.69). Processing speed tests allows one to measure cognitive abilities in a less biased form than intelligence tests, whereas school performance could be influenced in a positive or negative way by personality factors like self-concept, anxiety or motivation.