5th Annual Scholarship (April 2004)
made to Dr. Michelle Luciano from Australia
on the subject of The genetic and environmental factor structure underlying the NEO PI-R and its covariance with
Report Abstract (429 words):
The broad aim of this study is to investigate the genetic and environmental factor structure underlying the relationship between personality traits and cognition. For instance, previous studies have shown a relationship between the NEO Personality Inventory (-Revised) 'Openness to Experience' domain and intelligence test scores, and this was explored in the present study. By using a classical twin design, the proportion of genetic and environmental variance contributing to the correlation between Openness and Intelligence could be determined.
Measures of Openness (NEO PI-R), verbal and performance IQ (Multidimensional Aptitude Battery) and academic achievement (Queensland Core Skills Test) were obtained from an adolescent twin sample (N = 274 pairs). Openness was correlated 0.26 with verbal IQ, 0.14 with performance IQ, and 0.31 with academic achievement. Academic achievement was more strongly correlated with verbal (0.81) than performance (0.55) IQ, and verbal IQ and performance IQ correlated 0.50.
Structural equation modelling of the covariation between Openness, verbal IQ, performance IQ, and academic achievement in identical and non-identical twins enabled estimation of genetic and environmental sources of covariation between measures. Based on previous findings, a genetic factor structure was hypothesised that included 1) a general genetic factor, 2) a genetic factor influencing IQ and academic achievement, 3) a genetic factor influencing verbal IQ, 4) a genetic factor influencing performance IQ, and 5) a genetic factor influencing Openness (academic achievement, in this sample, has been previously shown to have no independent genetic influences outside of those shared with IQ). A model in which the general genetic factor loading on performance IQ was dropped did not fit the data, although the general factor's influence on performance IQ (factor loading of 0.47) was smaller than its influence on verbal IQ (0.62) and academic achievement (0.80). The general genetic factor explained more covariance between the IQ and academic achievement measures than did the genetic factor specified to influence only IQ and academic achievement. This suggests that Openness is related to general ability rather than to any specific aspect of measured intelligence. As a unique genetic influence on Openness was supported (explaining 28% of variance) this indicated some separation of Openness and Intelligence as unique constructs. The results further showed that the environment (common and nonshared) did not mediate any of the covariation between Openness and IQ or academic achievement.
This analysis will be expanded to include the facets of Openness, which may show different magnitudes of genetic correlation with the IQ and academic achievement measures. Future research will also be directed to the genetic and environmental relationship between other personality domains (especially Extraversion and Conscientiousness) and cognitive abilities.
Hans and Sybil Eysenck