### Factors Inducing Cybersickness
#### 1.1.1 Personal Characteristics  
User factors refer to the individual characteristics and traits of individuals who are directly exposed to virtual environments; these factors influence their susceptibility to cybersickness. User factors can be classified and explained on the basis of sensory conflict theory, considering factors related to the user, operation, and virtual environment. 1. User Demographic Characteristics (Age and Sex) Age and sex are significant demographic factors that influence the occurrence of cybersickness in virtual environments. 1. Age Studies, such as those by [PERSON] and [PERSON] (2022), have shown that younger individuals tend to have stronger defenses against cybersickness than older adults [4]. Research by [PERSON] et al. (2016) examining the vestibular perception threshold intensity revealed that vestibular perception ability typically begins to decline after the age of 40, becomes weaker after 60, and becomes significantly degraded after 70 [5]. This decline in vestibular perception may contribute to increased susceptibility to cybersickness among middle-aged and older adults. [PERSON] and [PERSON] (2020) reported that young children aged between 4 and 10 tolerated fully immersive 3D VR gameplay without significant side effects [6]. Additionally, studies have revealed differences in postural balance between younger and older individuals, indicating that reduced postural balance among older individuals may lead to increased susceptibility to cybersickness [7]. Therefore, age can be a factor in cybersickness. 2. Sex Some studies have indicated that there may be differences in the occurrence of cybersickness between sexes. [PERSON] and [PERSON] (2010) reported sex differences in cybersickness across three age groups, namely, 20-30, 40-50, and 60-70 years, with males outperforming females in all age groups [8]. [PERSON] et al. (2017) conducted a study on cybersickness induction on the basis of sex, sensory conflicts, and improvements in VR technology [9]. They analyzed data from 223 participants and concluded that females experienced more pronounced cybersickness than males did. Additionally, [PERSON] et al. (2020) conducted multiple experiments and reported that females were equally prone to cybersickness in virtual environments [10]. Their research suggested that improper interpupillary distance (the distance between the centers of the eyes) in head-mounted displays may be a major factor contributing to cybersickness in females. Therefore, they recommend redesigning head-mounted displays with adjustable interpupillary distances to reduce the occurrence of cybersickness in females. Overall, sex differences exist in cybersickness induction, with females generally being more susceptible than males are, although this effect is not as pronounced as that of age differences. 2. Susceptibility to Cybersickness [PERSON] and [PERSON] (2021) explored users' susceptibility to cybersickness through the HEXACO Personality Questionnaire [11]. All the participants were assessed on six dimensions of personality, including honesty-humility, emotionality, extraversion, agreeableness, conscientiousness, and openness to experience. The results of the study revealed that participants with high emotional levels had significantly higher scores on disorientation and dyskinesia. In addition, [PERSON] et al. (2021) demonstrated that a participant's individual sensitivity to motor parallax was predictive of the degree to which cybersickness was induced and that sensitivity to motor parallax and stereoscopic cords could be assessed through a depth perception discrimination task, which in turn could be used to determine susceptibility to cybersickness ([PERSON] et al., 2021). (3) Visual ability  
Owing to defects in the optical structure of the human eye, human visual ability has inherent limitations. Empirically, the quality of vision is reflected in the discrimination of small targets. Therefore, the earliest assessment of visual ability was based on the ability to see how small a target is ([PERSON] et al., 2021).