L’étude “Role of test motivation in intelligence testing” (2011) menée par Duckworth et ses collègues est régulièrement citée par les partisans “anti-QI” comme une preuve à l’encontre de la “thèse du QI”. Il y a premièrement un grand malentendu. Comme Duckworth et al. ont noté dans leur conclusion :
It is important not to overstate our conclusions. For all measured outcomes in Study 2, the predictive validity of intelligence remained statistically significant when controlling for the nonintellective traits underlying test motivation. Moreover, the predictive validity of intelligence was significantly stronger than was the predictive validity of test motivation for academic achievement. In addition, both Studies 1 and 2 indicate that test motivation is higher and less variable among participants who are above-average in measured IQ. These findings imply that earning a high IQ score requires high intelligence in addition to high motivation. Lower IQ scores, however, might result from either lower intelligence or lack of motivation. Thus, given closer-to-maximal performance, test motivation poses a less serious threat to the internal validity of studies using higher-IQ samples, such as college undergraduates, a popular convenience sample for social science research (43). Test motivation as a third-variable confound is also less likely when experimenters provide substantial performance-contingent incentives or when test results directly affect test takers (e.g., intelligence tests used for employment or admissions decisions).