Executive functions and successful behavior
Sammanfattning: Executive functions are the underlying mechanisms that drive top-down regulation of information processing. While suboptimal executive functions have been investigated in various groups of patients, their impact and contribution to behavioral success have not been clarified. It has been suggested that executive functions can be divided into simple executive functions, sometimes referred to as core executive functions, and more complex executive functions often involving other cognitive components referred to as higher order executive functions. Several cohorts of healthy individuals (in total 324 individuals) were investigated in five separate studies (Study I-V) to better understand how higher order executive functions are associated with successful human behavior. Due to its similarity to evolutionary conserved behaviors that depend on well-developed executive functions, including cognitive flexibility and creative fluency, and as well as due to its global impact, soccer was chosen for the three first studies. Soccer is practiced in a strictly controlled area with clear and common rules all around the world. It involves fast problem solving with the aim to reach the same goal in different ways. Soccer is also played by individuals of both sexes of widely different ages and has a shared understanding of how success is defined by both professionals and the audience. Soccer is therefore a good research arena to better understand how executive functions impact human behavior in constantly changing environments where individuals act as free agents but with a common goal and specific restrictions. Study I suggested that elite soccer players show significantly higher executive functions capacity than players on semi-elite level as well as compared to norms of the test. This result was conceptually repeated in Study III, in which national team players were compared with elite players from the same soccer clubs that had never been selected to play in national teams. The difference was especially evident when studying cognitive flexibility and creative fluency using the Design Fluency Test suggesting a better capacity for behavior adjustment. Moreover, this executive functions capacity was related to the number of scored goals and/or made assists under a prolonged measured period. Finally, cognitive flexibility correlated significantly on a moderate level with coach-rated game intelligence, i.e. the players’ ability to “read the game”, to anticipate the intentions of the opposite player and use that information to make successful decisions and actions. The main results from Study I and III were also shown for junior academy players, age range twelve to nineteen years, in Study II. Working memory (a core executive functions) had the most prominent role, suggesting a relation of the results to the maturation of the brain. Both core and higher order EF, but not IQ-measurements, significantly correlated on a moderate level with the number of scored goals the players made during two sessions. The next step was to assess the involvement of higher order executive functions in other nonsport situations where similar cognitive functions also may have a decisive role for success. Study IV showed that applicants for the Swedish counterterror intervention unit (Nationella Insatsstyrkan) had significantly better results in Design Fluency Test compared to average of the population and to police officer trainees mirroring the difference in level of play in soccer. Moreover, following the baseline tests, the applicants were re-tested after significant physical and psychological stress. The results showed that their re-test results declined compared to the expected result. However, there was still a significant correlation between the baseline results and the re-test results, indicating that higher capacity of executive functions could work as a resilience factor and safeguard adequate decision-making under stress. Finally, in Study V, different occupations in a medium sized company including forklift operators, sellers, operational and strategic managers were studied. The results showed that the capacity of cognitive flexibility and fluent creativity (both on a perceptual and a verbal level) correlated negatively with the amount of sick leave for the previous five years. The results remained after controlling for age, work group, sex, and other different cognitive components. Since we adjusted for work group, education and socio-economic factors, these did likely not explain the results. All together this thesis suggests that higher order of executive functions are important factors for success in several human behaviors and occupations. The results may need independent replication but this research project offers novel insights into how EF capacity is associated with behavioral success and that executive functions may represent a resilience factor to stress.
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