## 4 Discussion  
In the present study, subjects underwent four typical tests to assess postural stability. The trials included a combination of the width of the base of support (double- and single-leg stance) and visual control (eyes open and closed). Additionally, the big-five test (International Personality Item Pool NEO-Five Inventory 50) was used to assess personality. Postural fluctuations can be measured using different techniques [3]. These include linear and nonlinear measures. The most common linear parameters are path length, sway area, and sway velocity. The higher the values of the above measures, the more the person sways [5]. Recently, a growing body of papers has argued that postural stability is achieved through the interaction of many different systems. These interactions can occur both within a single sense and between senses (for example, visual and vestibular [2; 3; 5]). Thus, the resulting data may be inherently nonlinear. Consequently, they are best studied using analyses based on nonlinear dynamics approaches. This study aimed to explore the relationships between postural control assessed by nonlinear measures and the five-factor model of personality. Given that the functioning of the nervous system may be related to emotions [44; 45], we asked whether personality could be a determinant of postural control. Moreover, we hypothesized that individuals with different personalities may have different postural control under typical measurement conditions. In this study, we showed that the dominant personality traits in the study group were extraversion and agreeableness. It seems that such a result correctly characterizes the study group, which comprised physiotherapy students. Individuals with high levels of extraversion and agreeableness are characterized by, among others, compassion towards others, empathy, and caring towards other people (Table 1). This is the kind of personality a physicistherapist should have. This result is in line with the paper of [PERSON] [46]. The author showed that a higher level of economic performance, higher levels of educational enrollment, life expectancy, and GDP are associated with increased variability in personality across countries. It was associated with higher average levels of extraversion, emotional stability, and agreeableness. In our study, despite the division of the individuals into two groups differing in terms of personality, it was not possible to find differences between the parameters assessing postural control in individual trials (2 eo, 2 ec, 1 eo, and 1 ec). Thus, it is reasonable to conclude that personality is not a significant determinant of postural control and the hypothesis in the study group was disproved. It is worth noting that the tasks to which individuals were subjected were not intended to induce stress and thus affect the neurotic part of the personality. However, it is worth noting that the selected tests are the most commonly used in the clinic. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Trial** & **Correlations** & **Interpretation** \\ \hline \multirow{2}{*}{2 eo} & Agreeableness and SampEn\_ML (r = \(-\)0.37) & Low negative association \\  & Openness and SampEn\_AP (r = \(-\)0.44) & Low negative association \\ \hline \multirow{3}{*}{2 ec} & Neuroticism and FD\_ML (r = 0.47) & Low positive association \\  & Conscientiousness and FD\_ML (r = \(-\)0.34) & Low negative association \\  & Agreeableness and LyE\_ML (r = \(-\)0.41) & Low negative association \\ \hline \multirow{3}{*}{1 eo} & Neuroticism and FD\_ML (r = \(-\)0.50) & Moderate negative association \\  & Openness and LyE\_AP (r = 0.53) & Moderate positive association \\  & Openness and LyE\_ML (r = 0.59) & Moderate positive association \\ \hline \multirow{3}{*}{1 ec} & Openness and LyE\_AP (r = 0.37) & Low positive association \\ \cline{1-1}  & & \\ \end{tabular}
\end{table} 
Table 3: The significant Spearman correlations of personality traits scores with nonlinear parameter values within trials (\(p\leq 0.05\)).