Can personality factors predict intelligence?

Abstract

The present study investigated the relationship between personality traits and psychometric intelligence. A total of 4859 participants completed the Critical Reasoning Test Battery (GRT2) and the Fifteen Factor Questionnaire (15FQ). Of the second-order personality factors, Conscientiousness, Extraversion and Neuroticism were significant predictors of general intelligence (g). Regressing personality and demographic factors on g indicated that they accounted for 13% of its variance. The investigation of personality predictors of specific mental abilities (numerical, verbal and abstract reasoning) revealed that although some variables can be used to predict scores on all three abilities (e.g. Conscientiousness, Extraversion), other variables can be used to predict only specific abilities (e.g. Openness, Neuroticism). Regressing personality and demographic factors on specific abilities indicated that they accounted for 9–17% of the variance in intelligence scores.

Introduction

The present study is an investigation of the extent to which personality traits can predict psychometric intelligence. Intelligence and personality are usually treated as relatively distinct in the research on individual differences, however, many studies have shown that there are consistent predictable correlations between these two constructs (Ackerman and Heggestad, 1997, Austin et al., 2002, Collis and Messick, 2001, Furnham et al., 1998, Goff and Ackerman, 1992, Kyllonen, 1997, Zeidner, 1995). These studies have been based on a variety of intelligence and personality measures, which provides a broader understanding of the relationships between the two constructs, but has led to inconsistencies in the findings, which make interpretations difficult. Here we will summarize the findings that relate general, fluid and crystallized intelligence to the traits of the Five Factor Model of personality, which was proposed by McCrae and Costa (1987).

Out of the Big 5 personality factors, the one which has most consistently been found to correlate with intelligence is Openness (Zeidner & Matthews, 2000). Significant correlations have been found between Openness and general intelligence (Austin et al., 2002, Kyllonen, 1997, Moutafi et al., 2003), and between Openness and quantitative ability (Kyllonen, 1997). It has however been proposed that Openness more specifically correlates with crystallized intelligence (gc) (Brand, 1994). Indeed, correlations of the magnitude of r = 0.58 have been reported between Openness and verbal ability, which is a measure of gc (Kyllonen, 1997). Goff and Ackerman (1992) suggested that the relationship between gc and Openness may be mediated by Typical Intellectual Engagement (TIE), which is a measure of intellectual motives and interests.

Another factor, which has been found to be correlated with intelligence, is Extraversion (Zeidner & Matthews, 2000). Findings on this relationship have been controversial, in that Extraversion has been found to be both positively (Ackerman and Heggestad, 1997, Austin et al., 2002, Lynn et al., 1984) and negatively (Furnham et al., 1998, Moutafi et al., 2003) linked to measures of intelligence. It has been proposed that the relationship between Extraversion and intelligence is mediated by the nature of the intelligence test, due to Introverts having a higher resting level of cortical arousal than Extraverts (Eysenck, 1967, Eysenck, 1994). This suggestion is in line with Robinson (1985), who claimed that Extraversion is associated with intellectual styles and intelligence profiles and not with actual ability. More specifically, Extraverts have been found to perform better on timed tasks (Rawlings & Carnie, 1989) whereas Introverts tend to perform better in tasks requiring insight and reflection (Matthews, 1992, Saklofske and Zeidner, 1995).

Significant negative correlations have also been observed between Neuroticism and intelligence (Ackerman and Heggestad, 1997, Kyllonen, 1997, Moutafi et al., 2003). The negative sign indicates that individuals who score highly on Neuroticism tend to achieve lower intelligence scores. One of the sub-factors of Neuroticism, which seems to mediate the relationship between Neuroticism and intelligence, is anxiety. According to Eysenck (1979), high-anxiety individuals engage in significantly more task-irrelevant processing (worry) than low-anxiety individuals, which impairs their performance. Negative correlations between anxiety and intelligence have been reported (Moutafi et al., 2003) and experimental research has shown that anxiety can impair intellectual functioning in a variety of contexts, ranging from IQ tests to school achievement (Sarason, 1980, Hembree, 1988). It seems that Neuroticism is more related to intelligence test performance than to intelligence per se, in that it affects the test-taking experience, which in turn leads to lower scores (Moutafi, Furnham, & Tsaousis, submitted for publication).

The findings on the relationship between Conscientiousness and intelligence have been controversial. Ackerman and Heggestad (1997) reported a near zero correlation between Conscientiousness and g in their meta-analysis, a finding which was supported by Kyllonen (1997). However, a marginally significant negative relationship has been reported between Conscientiousness and creativity (Furnham, 1999), and most importantly, recent studies have reported negative correlations between Conscientiousness and measures of intelligence (Allik and Realo, 1997, Demetriou et al., 2003, Furnham et al., submitted for publication, Moutafi et al., 2003; Moutafi, Furnham, & Paltiel, 2004). It has been suggested that less intelligent individuals, from competitive school, academic or business institutions, may become more conscientious in order to cope with their disadvantage. It is also possible that more intelligent individuals do not become so conscientious, as they can rely on their intelligence to accomplish most tasks.

The only factor of the Big 5 that has not been found to be related to intelligence is Agreeableness (Ackerman and Heggestad, 1997, Furnham et al., submitted for publication, Austin et al., 2002, Kyllonen, 1997).

The aim of this study was to investigate the relationship between personality and intelligence, using valid psychometric tests hitherto not reported in this specific literature. These tests were used not only to extend our understanding of the relationship between the two constructs, but also to provide psychologists in the occupational field, who use these tests for recruitment and selection, with an understanding of how the measures they use for assessment are theoretically interrelated. In order to obtain a more comprehensive picture, three measures of intelligence were used (numerical reasoning, verbal reasoning and abstract reasoning), in addition to a measure of general intelligence (which was derived from factor analysis of these three). These scores were related to a particular measure of the Big 5, which is used in occupational settings, but has not yet been widely used for research purposes.

The first hypothesis (H1) is that Openness will be a significant positive predictor of verbal and numerical reasoning, and of general intelligence. This would support Kyllonen (1997), who found Openness to be positively correlated with verbal ability, quantitative ability, and g. The second hypothesis (H2) is that Extraversion will be a significant positive predictor of the three intelligence tests, as they are timed tests, which have been found to favor Extraverts (Rawlings & Carnie, 1989). The third hypothesis (H3) is that Neuroticism will be a significant negative predictor of general intelligence, in line with Ackerman and Heggestad (1997), and of the three intelligence measures (numerical, verbal, abstract reasoning), in line with the suggestion that Neuroticism is related to intelligence test performance (Moutafi et al., submitted for publication). The fourth hypothesis (H4) is that Conscientiousness will be a significant (negative) predictor of general intelligence, in line with Demetriou et al. (2003) and Furnham et al. (submitted for publication).

In the statistical analysis of the data, gender and age of the subjects will be controlled for, as these demographic factors have been found to correlate with intelligence. There is a general consensus is that males and females do not differ in general intelligence (APA Public Affairs Office, 1997, Hyde and Linn, 1988, Loehlin, 2000, Matthews et al., 2000), although some researchers oppose with this (Lynn, 1994, Lynn, 1999). Sex differences have however been reported in the variance of IQ scores, with males showing greater variability (Feingold, 1992) and more importantly, researchers have found significant sex differences in specific abilities (Matthews et al., 2000). In the study of age-related differences in cognitive ability, there is a general consensus that scores on intelligence tests tend to decline with age (Schaie, 1994), with fluid intelligence peaking at the age of 16 or 17 and crystallized intelligence peaking within the age range of 45–54 (Ryan, Sattler, & Lopez, 2000). Researchers however also advocate for the stability of intelligence (Deary, Whalley, Lemmon, Crawford, & Starr, 2000), due to a change in the genetic over the environmental contribution across the lifespan (Plomin, Pedersen, Lichtenstein, & McClearn, 1994).