A behavioural genetic study of mental toughness and personality

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Abstract

The present study is the first behavioural genetic (BG) investigation of mental toughness, as measured by the 48-item mental toughness (MT48) questionnaire, and the first BG investigation of relationships between mental toughness and the Big-5 factors of personality. Participants were 219 pairs of adult monozygotic and dizygotic twins from across North America. Twin study methodology was used to determine the extent to which genes and/or environmental factors contributed to individual differences in mental toughness and also to determine the genetic and/or environmental basis of any relationship between mental toughness and personality. Univariate BG analyses revealed that individual differences in mental toughness (as well as in personality) were largely attributable to genetic and nonshared environmental factors. Bivariate BG analyses revealed that phenotypic correlations between mental toughness and personality were largely attributable to common genetic and common nonshared environmental factors.

Introduction

Behavioural genetic (BG) studies investigate the extent to which genetic and environmental factors contribute to individual differences in behavioural traits. The aim in conducting the current research is to determine the genetic and environmental influences on a relatively newly defined construct termed mental toughness and also to investigate relationships between mental toughness and the Big-5 personality traits at the phenotypic, genetic, and environmental levels.

Mental toughness has recently been defined by Clough, Earl, and Sewell (2001). These researchers developed a definition of mental toughness based on the established psychological concept known as the ‘hardy personality’ that was first proposed by Kobasa (1979). Hardiness consists of three main components: control, the ability to feel and act as if one is in control of various life situations; commitment, the tendency to involve rather than distance oneself from whatever one is doing; and challenge, the ability to understand that change is normal.

Clough et al. (2001) collected qualitative information from athletes and were able to categorize most of the factors the athletes identified as necessary for one to be mentally tough into Kobasa’s (1979) hardiness model; however, there were some elements that did not apply to any of the three hardiness categories. As a result, Clough et al. (2001) determined that a mental toughness model requires a fourth category: confidence. The researchers note that “confidence is an important factor relating to sport performance [and one that] has not been considered as a distinct element in previous models of hardiness” (p. 38). As such, Clough et al. (2001) created what they call the ‘4Cs model of mental toughness’: control, commitment, challenge, and confidence. The definition these researchers have developed by gathering evidence from research, athletes, coaches, and sport psychologists is as follows:

Mentally tough individuals tend to be sociable and outgoing; as they are able to remain calm and relaxed, they are competitive in many situations and have lower anxiety levels than others. With a high sense of self-belief and an unshakeable faith that they control their own destiny, these individuals can remain relatively unaffected by competition or adversity (p. 38).

Clough et al. (2001) also developed a 48-item mental toughness questionnaire (the MT48) that provides an overall score of mental toughness and scores on the 4C’s subscales. Based on data collected from 600 athletes, Clough et al. (2001) reported that the reliability of this scale was .90. Although mental toughness is related to the older construct of hardiness, studies have demonstrated that they are nonetheless distinct: the main difference being that mental toughness, in particular as measured by the MT48, represents an extension of hardiness with its assessment of confidence in addition to control, challenge, and commitment (Clough et al., 2001, Golby and Sheard, 2004).

Although many models of personality have been proposed (Eysenck and Eysenck, 1969, McCrae and Costa, 1989, Tellegen et al., 1985), currently, the most widely accepted is the ‘Big-5 theory’ proposed by Costa and McCrae (1992). The Five Factor Model includes extraversion, agreeableness, conscientiousness, openness to experience, and neuroticism. These five factors of personality have been found to account for the majority of individual differences that exist between people in most personality traits (Costa & McCrae, 1992).

Most studies have demonstrated that genes and nonshared environmental factors account for the majority of individual differences among people in personality (Loehlin, 1992). In fact, research has shown that individual differences in almost all facets of the Big-5 factors of personality can be explained by genetic and nonshared environmental influences (Jang, Livesley, Angleitner, Riemann, & Vernon, 2002). Plomin, DeFries, and McClearn (1990), estimate that the average heritability for any given personality trait is approximately 50%.

The current study uses the MT48 questionnaire to define and measure mental toughness. This study will determine the extent to which genes and/or environmental factors contribute to the development of individual differences in mental toughness. Although prior BG studies have reported a genetic component to constructs related to mental toughness, such as behavioral resilience, cognitive resilience to socioeconomic deprivation, and task persistence (Deater-Deckard et al., 2006, Kim-Cohen et al., 2004), no previous BG research has examined the multiple dimensions of mental toughness identified by Clough et al. (2001). Moreover, the current study goes beyond estimating the contribution of genetic and environmental factors to individual differences in mental toughness by also determining whether any phenotypic correlations between mental toughness and personality are themselves attributable to correlated genetic and/or environmental factors.

Clough et al. (2001) assert that “mentally tough individuals tend to be sociable and outgoing” (p. 38). Given this description, and the fact that studies have shown significant positive associations between hardiness, resiliency, and extraversion (Campbell-Sills et al., 2006, Maddi et al., 2006), it is expected that mental toughness will be positively correlated with extraversion. Also from Clough et al’s (2001) definition, it is expected that a positive correlation will be found between mental toughness and agreeableness and conscientiousness: people who are “relatively unaffected by competition or adversity” may also be viewed as being agreeable; and those who believe they “control their own destiny” or who score high on Commitment are likely to also be conscientious. Clough et al. (2001) also state that individuals high on mental toughness experience low anxiety and have a high sense of self-belief; from this, it is expected that a negative correlation will be found between mental toughness and neuroticism. Again, previous studies have reported significant negative correlations between hardiness, resiliency, and neuroticism (Campbell-Sills et al., 2006, Maddi et al., 2002), although others have noted that the relationship between hardiness and neuroticism is not so pronounced as to render the two constructs redundant (Benishek and Lopez, 1997, Campbell-Sills et al., 2006, Maddi et al., 2002, Sinclair and Tetrick, 2000). Finally, at the component level, it is predicted that there will be a positive correlation between challenge and openness to experience because both constructs reflect an appreciation for new experiences. Based on previous behavioural genetic studies of other personality traits, it is expected that any observed phenotypic correlations between mental toughness and personality will primarily be attributable to common genetic and common nonshared environmental factors.

Section snippets

Participants

Participants were 152 pairs of monozygotic (MZ) and 67 pairs of dizygotic (DZ) adult twins. There were 438 participants in total comprising 30 pairs of male MZ twins, 122 pairs of female MZ twins, eight pairs of male DZ twins, and 59 pairs of female DZ twins. The participants ranged in age from 18 to 82 years (M = 23.88, SD = 6.22). The twins were recruited from newspaper advertisements placed in newspapers and magazines across North America. Initial contact was made by the twins and they provided

Results

Clough et al. (2001) did not report conducting any factor analyses of the MT48, so we conducted exploratory and confirmatory factor analyses on our data to test the presence of the four factors that the scale was developed to measure. Twins within each pair were arbitrarily designated as “twin 1” and “twin 2” and exploratory analyses were performed separately among all the “twin 1’s” and then among all the “twin 2’s” in order to have independent observations. In each of these analyses the scree

Discussion

There were two goals in conducting the current research: first, to examine the extent to which genetic and environmental factors contribute to individual differences in a newly defined construct called mental toughness as measured by the MT48; second, to examine the extent to which mental toughness would correlate with the Big-5 personality dimensions and the extent to which any phenotypic correlations between these would be attributable to correlated genetic and/or correlated environmental

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