CONSCIENTIOUSNESS, MENTAL TOUGHNESS AND INDIVIDUAL SOCCER PERFORMANCE

As previously emphasised, conscientiousness represents a meaningful predictor of individual performance, with validity generalisation across jobs, organisations and academic contexts, as supported by several comprehensive meta-analyses (Potočnik et al., 2021; Richardson et al., 2012; Salgado, 2017). In competitive sports settings, extant empirical evidence is incomparably less developed. However, prior empirical studies ascribe plausibility to the role of this disposition as a driver of athletic success, by showing that athletes reporting stronger conscientiousness scores tend to rely upon more effective preparation and coping strategies, accomplish stronger long-term performance and often operate at higher competitive levels (Allen et al., 2013; Allen & Laborde, 2014, for reviews). Of the remaining big five, extraversion and mostly emotional stability have also been found to exert a positive influence on some of these outcomes.

Similarly, findings pertaining to this study’s specific scope, i.e. personality in competitive soccer, albeit limited, suggest that conscientiousness represents a valid predictor of individual soccer performance outcomes. Specifically, an early study conducted by Piedmont et al. (1999), with a sample of 79 female athletes aged between 18 and 21 years old, reported a positive and sizeable link between conscientiousness and coaches’ ratings on different dimensions of soccer performance (r = .33, p < .01), e.g. athletic ability, team plainness and work ethic, as well as between this disposition and a set of game performance objective indices (r = .30, p < .01), e.g. scores, assists and games played. Meaningful links with both criteria composites were also reported for emotional stability. Notwithstanding, whereas both these personality factors accounted for 23% of the variance in coaches’ ratings, only conscientiousness yielded a significant contribution of 8% for the prediction of objective performance. Another soccer-specific study carried out by Ruiz-Barquín and García-Naveira (2013) with a sample of 128 male soccer players aged between 14 and 24 years old from Spanish soccer competitions reported positive, but smaller correlates between some big five factors and game performance, assessed via coach ratings, specifically of r = .19 (p < .05) for emotional stability, r = .18 (p < .05) for openness, and r = .15 (p < .10) for conscientiousness.

More recently, Kalinowski et al. (2020), relying on a sample of 122 young male soccer players from Polish championships, reported a significant contribution of conscientiousness, neuroticism and extraversion to predicting the effectiveness of soccer game performance, measured through players’ specific tactical and technical actions (e.g. shots at goal, passes on target). Lastly, a study developed by Steca et al. (2018), with Italian male non-athletes and athletes belonging to different competitive levels of individual and team sports, including soccer, found that levels of athletic involvement and competitive achievement can be effectively distinguished using the big five, since athletes from higher competitive levels also reported stronger scores of conscientiousness, emotional stability and agreeableness. Furthermore, the largest effect size in differentiating between athletes at a high and low competitive level was yielded by conscientiousness.

Overall, these preliminary findings provide support for the usefulness of the big five taxonomy for the prediction of sport and particularly soccer performance outcomes, further suggesting that conscientiousness may represent one of its most important dispositional predictors. This converges with results from other research pertaining to other achievement settings, such as academic and work contexts. As underlined by Allen et al. (2013), athletic success is partly determined by individual capacity, as happens in other human performance domains. But it is also influenced by the willingness to perform, through the display of behavioural patterns and habits of effort and perseverance, which are considered the expression of the core attributes of conscientiousness (Costa & McCrae, 1992). Thus, considering these conceptual and empirical aspects, we anticipate that this factor will emerge as a significant predictor of soccer performance and hypothesise that:

Hypothesis 1: Conscientiousness is positively related to individual soccer performance.

Mental toughness has emerged as one of the most prevalent concepts of positive psychology in the literature (Rusk & Waters, 2013). Under the assumption that it entails a set of positive psychological resources involved in top performance achievement, related research has recently broadened its focus to uncover mental toughness links with academic and work performance, providing encouraging preliminary findings that support its validity in predicting such outcomes (Gucciardi et al., 2015; McGeown et al., 2016). In sports and exercise contexts, mental toughness has received a consistently higher level of interest from both conceptual and empirically focused research (Gucciardi, 2020).

Despite the proliferation of research on mental toughness, particularly over the last two decades, its conceptualisation (trait vs. state-like), dimensionality (unidimensional vs. multidimensional), distinctiveness from related psychological constructs (e.g. hardiness, resilience), and measurement remain part of an ongoing debate (Gucciardi et al., 2015; Papageorgiou et al., 2018). Most previous research has drawn on multidimensional models, particularly the 4Cs model of Clough et al. (2002), which posits this construct as a personality trait akin to psychological hardiness and encompassing the subcomponents of control, commitment, challenge and confidence. However, more recent empirical efforts have challenged its multidimensionality and dispositional nature, pointing towards a unitary, state-like conceptualisation of mental toughness (e.g. Gucciardi et al., 2015).

As previously noted, this latter unidimensional conceptualisation is adopted in the current study, therefore positing this construct as a “state-like psychological resource that is purposeful, flexible and efficient in nature for the enactment and maintenance of goal-directed pursuits” (Gucciardi, 2017, p. 18). Hence, mental toughness is conceived as a set of psychological resources, implied in successful coping and goal attainment when individuals are facing challenging or stressful circumstances, being: purposeful, i.e. characterised by giving direction and energy towards self-referenced goals; efficient, i.e. holding congruency between actions and objectives; and flexible, enabling adaptation of regulatory processes across stressors and situational demands (Gucciardi, 2017, 2020).

Despite the relevant ongoing debates about the concept, measurement and distinctiveness of this construct, previous qualitative studies, focused on its conceptual span and encompassing attributes, have consistently reported that mental toughness is perceived by elite athletes, coaches and sport psychologists as a key requirement for achieving and sustaining high levels of performance across sports (e.g. Anthony et al., 2016; Jones et al., 2002, 2007), including in soccer (Coulter et al., 2010; Thelwell et al., 2005). Moreover, most findings from prior quantitative research, although more limited and relying on distinct mental toughness conceptualisations, support the positive influence of this construct on sports performance, as it shows an association with greater athletic achievement ranks and several competitive sport performance indices (e.g. Cowden, 2017; Liew et al., 2019, for reviews).

With a particular interest for this study, evidence from soccer settings, albeit particularly scarce, also suggests that players from the highest competitive levels (e.g. elite leagues and national teams) tend to report significantly higher scores of mental toughness in comparison to those competing at a lower level. One of these empirical studies was conducted by Danielsen et al. (2017) with a sample of 298 female soccer players from three Norwegian leagues, showing that elite league players reported significantly higher mental toughness scores than players from the third league. Yet, no significant differences were obtained between the players of the elite and the second league, nor between the players of the second and the third league. Another soccer-specific study was carried out by Guillén and Santana (2018), with a sample of 242 male Spanish players, from an age range of 14-19 years. They reported significant differences in mental toughness depending on players’ age and team classification in the league, with the highest scores obtained for older players and for those playing for the top-ranking team in each performance category (i.e. under 16s and under 19s). The results also showed that players’ mental toughness scores were positively correlated with their perceptions regarding their ability to play in a superior category. Lastly, a study conducted by Kristjánsdóttir et al. (2019), with a sample of 142 Icelandic female soccer players, revealed that significantly higher scores of mental toughness were found between the three competition levels under analysis (i.e. national team, first and second divisions).

In line with these empirical findings and acknowledging the instrumentality of mental toughness to cope with competition demands and pursue and excel in performance goals, regardless of contextual pressure and adversity (Gucciardi, 2020; Papageorgiou et al., 2018), including in soccer (Coulter et al., 2010; Thelwell et al., 2005), we expect that mental toughness will exert a positive influence upon individual soccer performance and thereby hypothesise that:

Hypothesis 2: Mental toughness is positively related to individual soccer performance.

MEDIATING ROLE OF MENTAL TOUGHNESS ON THE CONSCIENTIOUSNESS-SOCCER PERFORMANCE LINK

As reviewed above, both conscientiousness and mental toughness have been examined as antecedents of individual performance across several achievement settings, such as sports, educational and work contexts (Cowden, 2017; Lin et al., 2017; McGeown et al., 2016). While their predictive validity for individual performance has been supported by initial research, assessment of their joint effects on performance outcomes remains unexplored, preventing a more comprehensive understanding of how they may build up together and impact individual performance. Drawing upon the theory of individual differences in performance of Motowidlo et al. (1997) and following Gucciardi et al.’s (2015) conceptualisation of mental toughness as a characteristic adaptation, the current study proposes that mental toughness acts as an intervening mechanism on the link between conscientiousness and soccer performance.

As noted, according to Motowidlo et al.’s (1997) theoretical developments, individual differences in personality and mental abilities, combined with learning experiences, impact indirectly performance behaviours by affecting specific knowledge, skills and habits (i.e., characteristic adaptations). As posited by these authors, while abstract basic tendencies comprise enduring capacities and dispositions, including the big five, characteristic adaptations are the combined product of basic tendencies and learning processes, since they are built up through the interaction between individuals’ basic tendencies and their environment. As discussed by Gucciardi et al. (2015), in view of their findings indicating that while 44% of total variance in mental toughness results from between-person differences, more than half of its variance (i.e., 56%) was due to within-person variance over time, mental toughness should be interpreted as a characteristic adaptation, i.e. a contextualised expression of dispositions activated and shaped by environmental factors.

Building upon these aspects, we propose that conscientiousness represents a particularly important dispositional root of mental toughness, since it encompasses enduring core individual tendencies to show intentional and diligent behavioural persistence toward goal attainment (Costa & McCrae, 1992). Therefore, it is clearly linked to mental toughness, when asserted as a characteristic adaptation subsuming psychological resources that are relevant for goal-directed pursuits (Gucciardi, 2017). Consistently, previous findings regarding the relationships between the big five and mental toughness, despite being limited, have identified conscientiousness among the strongest obtained correlates, along with neuroticism and extraversion (i.e. Delaney et al., 2015; Yankov et al., 2019).

Thus, the current study postulates that mental toughness, as an instrumental characteristic adaptation for fulfilling challenging goals, like those involved in competitive sports, will act as a route through which the distal influence of conscientiousness impacts on soccer performance, and it is hypothesised that:

Hypothesis 3: Mental toughness mediates the relationship between conscientiousness and individual soccer performance.

PARTICIPANTS

This study sample was composed of 130 male soccer players aged between 17 and 37 years (M = 25.74, SD = 4.70) belonging to Portuguese teams, from amateur (56.9%) and professional official leagues (43.1%) of the Portuguese Football Federation (FPF). The majority of players were Portuguese (73.1%), with the remainder being of other nationalities, including Brazilian (13.1%), Cape Verdean (7.7%), Angolan (3.1%) and Spanish (3.1%).

Overall, 56.2% played in defensive positions, whereas 43.8% had attacking positions, with an average club tenure of 2.90 years (SD = 3.55). In terms of players’ education level, 13.9% were college graduates, 66.9% had completed high school, and 16.2% and 3% had completed the third and second cycles of basic education, respectively.

PROCEDURE

A concurrent validation design was employed, using paper and pencil questionnaires for data collection. After granting permission from the board of the target club, questionnaires were administered by a research team member to all players who agreed to participate. The main research goals were briefly mentioned in the first section of the questionnaire and participants’ informed consent was requested, emphasising the anonymity of all answers and their exclusive use for research purposes. In the second section, players were instructed to provide relevant sociodemographic data and answer conscientiousness and mental toughness measures. The third section included the assessment of players’ individual soccer performance, by instructing them to rate their respective physical, technical and tactical performance levels, as exhibited in the first half of the season (i.e. approximately over the last six months).

Players were also required to provide objective performance statistics, specifically the total amount of minutes they played in their team’s official games. To maximise the accuracy of reported statistics, a spreadsheet containing all team player-related game statistics, from an official source, was made available to the research team for their consultation during the sessions of data collection.

MEASURES

Conscientiousness. This factor was assessed through the respective four-item subscale from the Mini International Personality Item Pool (Mini-IPIP; Donnellan et al., 2006), provided with a five-point Likert-type scale, ranging from 1 (very inaccurate) to 5 (very accurate). Sample items included “I get chores done right away” and “Like order”. The aforementioned authors have provided evidence supporting the psychometric adequacy of this instrument and its usefulness as a brief measure of the big five. Cronbach’s α was .73 in the present sample.

Mental toughness. The eight-item Mental Toughness Index (MTI; Gucciardi et al., 2015) was employed to assess this construct. Players were instructed to rate the extent to which each item constitutes an indication of how they usually think, feel and behave as a performer in their setting, by using a 7-point Likert-type scale ranging from 1 (false, 100% of the time) to 7 (true, 100% of the time). Sample items include “I consistently overcome adversity” and “I am able to regulate my focus when performing tasks”. Consistent with previous research (i.e. Gucciardi et al., 2015), principal component analysis uncovered a single-component solution in the current sample data, supporting the unidimensionality of mental toughness, as measured by MTI. This solution accounted for 51.32% of the total variance and yielded appropriate item loadings, ranging from .59 to .84. Cronbach’s α was .87.

Individual soccer performance. Both subjective ratings and objective soccer game statistics were used as measures of player performance, following the same procedure adopted in previous related research (e.g. Lenz et al., 2020; Piedmont et al., 1999).

Subjective performance. An individual subjective performance index was obtained via players’ self-ratings regarding their physical, technical and tactical levels, exhibited throughout the first half-season, given the recognition of these dimensions as core factors of soccer performance and success (Elferink-Gemser et al., 2012; Gledhill et al., 2017; Kalinowski et al., 2020). Hence, players were instructed to rate their individual performance using a three-item scale provided by using a 7-point Likert-type scale, anchored from 1 (very poor) to 7 (outstanding), where each performance aspect (i.e. physical, technical and tactical) was assessed using a specific item, for example, “Overall, my tactical performance since the beginning of the season until the present was…”. Results from a principal component analysis uncovered a single solution accounting for 64.22% of the total variance, with respective item loadings ranging from .78 to .81, supporting the aggregation of obtained players’ ratings as a subjective index of global individual soccer performance. The corresponding Cronbach’s α was .71.

Objective performance. As for objective performance, it was operationalised using players’ individual game official statistics, consistent with the approach adopted in prior soccer studies (e.g. Lenz et al., 2020; Piedmont et al., 1999). Adopting the operationalisation procedure of Lenz et al. (2020), objective performance was assessed using the proportion of minutes each player had participated in team official games during the first-half season, in relation to the total amount of minutes from all games played by the team throughout that competition period.

Control variables. Consistent with previous research, players’ age, education, club tenure, soccer league type (i.e. professional vs. amateur) and field position (i.e. defending or attacking positions) were also measured to control for their possible effects on player performance (Elferink-Gemser et al., 2012; Han & Dongen, 2015).

MAIN THEORETICAL AND APPLIED CONTRIBUTIONS

The current study was carried out following prior calls for more research examining whether the big five, especially conscientiousness, could hold equivalent virtues as meaningful predictors of performance in sports settings, such as soccer (Musculus & Lobinger, 2018), as they have proven to hold for predicting work and academic performance (e.g. Richardson et al., 2012; Salgado, 2017). By focusing on conscientiousness, our findings support such status of this personality disposition in relation to soccer, by showing its positive and moderate links with both subjective and objective soccer performance criteria. Hence, these results are consistent with extant empirical findings supporting the merits of conscientiousness as one of the more relevant dispositional predictors of sports performance (Allen et al., 2013; Allen & Laborde, 2014), ascribing relevance to the almost intuitive propositions that its core traits of goal-focused effort, perseverance and discipline are drivers of individual performance across achievement contexts, such as competitive soccer (Kalinowski et al., 2020; Piedmont et al., 1999; Steca et al., 2018).

Another contribution from the current study stems from the examination of the predictive validity of mental toughness in the specific soccer domain, given the acknowledged need for more empirical research which scrutinises whether this construct should be considered among the key psychological determinants of success in athletic performance and development (Coulter et al., 2010; Gucciardi, 2020; Roberts & Woodman, 2017). Positive links obtained with both objective performance and subjective soccer performance measures, mostly with the latter, ascribe plausibility to previous theoretical assumptions regarding the role of mental toughness in prompting and maintaining goal-focused endeavours toward the achievement of high levels of performance in challenging and stressful circumstances (Gucciardi et al., 2015; Jones et al., 2002; Papageorgiou et al., 2018). Thus, our findings support such a role in soccer and suggest that Gucciardi’s (2017, 2020) unitary conceptualisation of this construct, as a state-like psychological resource implied in challenging goal attainment, holds pertinence for the prediction of sports outcomes, specifically in soccer settings.

Besides reporting the isolated links of conscientiousness and mental toughness with soccer performance, the current study ultimately aimed to contribute to a better understanding of how these two meaningful antecedents may jointly impact performance. As such, by drawing upon Motowidlo et al.’s (1997) theory and Gucciardi et al.’s (2015) conceptualisation of mental toughness as a characteristic adaptation, it has proposed and tested the intervening role of mental toughness on the influence of conscientiousness on individual soccer performance as a distal determinant. Indeed, enduring and state-like commonalities regarding persistence and effort toward performance goal accomplishment (Costa & McCrae, 1992; Gucciardi, 2017) that underpins conscientiousness and mental toughness constructs, respectively, add plausibility to this assertion that they may build up and sequentially impact performance. Hence, our findings are consistent with the proposed theoretical rationale, by supporting the statement that “basic tendencies directly affect characteristic adaptations, which in turn, directly impact upon individual objective biography” (Motowidlo et al., 1997, p. 78), the latter referring to soccer performance behaviours in the scope of this study. Specifically, the results revealed this mediating effect for subjective performance criteria, supporting the assertion that mental toughness may represent a contextualised expression of conscientiousness enacted and mutually influenced by environmental factors, in this case pertaining to soccer-related learning processes and competitive demands. Thereby, these findings suggest that mental toughness should be further examined in causal modelling of individual soccer performance, particularly in the scope of the characteristic adaptations (i.e. together with relevant sport’s skills, habits and instrumental knowledge) through which conscientiousness indirectly enacts critical player’s behaviours, such as those encompassed by the tactical, physical and technical dimensions of soccer performance. In parallel, these findings also support Motowidlo et al.’s (1997) model, as a relevant framework for future research on the impact of individual difference constructs and other psychological variables on human performance beyond its original work context, such as sports.

Still, for objective performance, only the direct effect of conscientiousness has received empirical support, suggesting that this disposition’s influence on the overall number of minutes officially played by sampled soccer athletes seems to occur via other mechanisms. Unlike subjective performance, which tends to focus exclusively upon factors under the players’ discretion, i.e. their physical, tactical and technical actions and determination, objective performance indexes, such as the number of played minutes, tend to suffer contamination from factors beyond the players’ control, including the coach’s specific game strategy, fatigue management and related choices, which ultimately affect their game participation. Extant evidence shows that more conscientious athletes tend to take fewer reckless risks and develop more favourable relationships with coaches and teammates (see Allen & Laborde, 2014, for a review), along with their stronger adherence to rules and instructions. Thus the dispositional effects of conscientiousness in objective performance, when measured in played minutes, could be mainly prompted via these other possible mechanisms, instead of players’ mental toughness. Future research accounting for such variables’ effects is needed before more conclusive findings can be made.

Along with the discussed theoretical contributions, the current findings also provide some practical implications. Specifically, the obtained results support the inclusion of conscientiousness and mental toughness in the psychological assessment of soccer players for selection and talent development purposes, given its meaningful positive effects on individual soccer performance, as previous research started to show (e.g. Danielsen et al., 2017; Guillén & Santana, 2018; Piedmont et al., 1999). Furthermore, in light of research suggesting that players’ mental toughness can be enhanced through focal intervention, such as the creation of an autonomy-supportive coaching environments (i.e., contexts conducive to mastery development, non-hostile interactions and positive social constellations) and the related nurturing of basic psychological needs (Gucciardi et al., 2009; Mahoney et al., 2014), coaches and technical staff should capitalise on these aspects to promote the benefits of mental toughness for performance. Specifically, they can foster such supportive environments and focus on developing players’ mental toughness core psychological resources, such as self-efficacy and emotional regulation. For example, players’ self-efficacy can be enhanced through frequent exposure to challenging tasks and enactive mastery, by providing opportunities for repeated performance success in challenging but progressively attainable aspects of soccer training and learning. Moreover, coaches should use verbal persuasion to increase players’ confidence in their competence to master soccer’s training and competition goals (see Bandura, 1986, 1997 for further details). In terms of emotional regulation, coaches and support staff should promote positive feelings and emotions among players during these endeavours in order to broaden players’ attentional focus and build psychological resources, rather than buffering individual and team stress and insecurity that undermine players’ attention and impair their cognitive flexibility (Frederickson, 2005).