## 4 Discussion
Going deeper, we tried to find associations between the results of nonlinear parameters counted for successive trials (2 eo, 2 ec, 1 eo, and 1 ec) and personality traits among all studied individuals. We have shown that in the 2 eo, there is a low negative association between sample entropy with agreeableness and openness. Such a result can be explained by the fact that the greater the regularity and complexity of a signal, and the amount of attention given to the performance of a given task (high sample entropy), the lower is the dominance of agreeableness and openness. Standing on two legs with eyes closed (2 ec) resulted in a low positive association of fractal dimension (calculated in ML direction) with neuroticism and a low negative association with conscientiousness. According to [PERSON] and [PERSON] [3], higher FD values indicate a more complex and irregular signals over time. Thus, in this trial, an increase in the complexity of the CoP signal may be slightly associated with individuals with a higher neuroticism component and lower conscientiousness. Furthermore, this test showed a low negative association of the Lyapunov coefficient (calculated in the ML direction) with agreeableness. It is worth noting that higher LyE values indicate the ability to respond more quickly to destabilizing stimuli and better balance control [47]. This result may suggest that individuals who display a high LyE in the lateral-medial direction during 2 ec have a low agreeableness component. On the other hand, the performance of the 1 ec test causes the openness component to increase with the increase in the LyE value (low positive association). All the above correlations were at low levels. Nevertheless, stronger positive associations of the Lyapunov exponent with openness appeared during the one-leg standing test with eyes open (1 eo). Thus, as openness increases, the body's response to destabilizing stimuli may increase faster. In the same trial, the increased values of FD in the ML direction were accompanied by a moderate decrease in neuroticism. From a clinical perspective, individuals with high neuroticism scores should be better managed. They tend to become upset quickly, appear constantly stressed, and cope inappropriately with psychological stress [24]. It is well known that fear and anxiety affect postural control [12]. Individuals with anxiety disorders, phobias have changes in balance control compared with healthy controls [48]. People suffering from depression resulted in increased postural stability (greater ellipse area indicating worse postural control) in working memory tasks (dual-task) [49]. To test how emotions influence postural control, researchers manipulated fear and anxiety in individuals using a different height of the surface (height-induced postural threat) [50], showing pictures known to elicit negative emotional responses [51]. In addition, studies on social evaluative threat have demonstrated the influence of emotion on postural control. The evaluative social threat was due to the evaluative audience or social comparison. [PERSON] et al. [52] showed that stress induced using a combination of arithmetic tasks and social evaluative threat leads to systematic changes in postural control. The introduction of social evaluative threat caused a reduction in postural sway and increased reaction time relative to the time pressure condition. Significant increases in frequency and amplitude were observed during a two-legged stance without vision control while being assessed by an evaluator [53]. [PERSON] [18] investigated whether young adults with asthma have impaired balance, and whether this impairment is related to altered musculoskeletal function and/or psychological characteristics. Participants with asthma showed a different postural control strategy in the absence of any obvious balance impairment. They were characterized by more regular dynamics (lower values of sample entropy in anterior-posterior direction) compared with controls.