title: Evaluation of adaptation to visually induced motion sickness based on the maximum cross-correlation between pulse transmission time and heart rate.
abstract: BACKGROUND
  Computer graphics and virtual reality techniques are useful to develop automatic and effective rehabilitation systems. However, a kind of virtual environment including unstable visual images presented to wide field screen or a head mounted display tends to induce motion sickness. The motion sickness induced in using a rehabilitation system not only inhibits effective training but also may harm patients' health. There are few studies that have objectively evaluated the effects of the repetitive exposures to these stimuli on humans. The purpose of this study is to investigate the adaptation to visually induced motion sickness by physiological data.
  
  
  METHODS
  An experiment was carried out in which the same video image was presented to human subjects three times. We evaluated changes of the intensity of motion sickness they suffered from by a subjective score and the physiological index rho(max), which is defined as the maximum cross-correlation coefficient between heart rate and pulse wave transmission time and is considered to reflect the autonomic nervous activity.
  
  
  RESULTS
  The results showed adaptation to visually-induced motion sickness by the repetitive presentation of the same image both in the subjective and the objective indices. However, there were some subjects whose intensity of sickness increased. Thus, it was possible to know the part in the video image which related to motion sickness by analyzing changes in rho(max) with time.
  
  
  CONCLUSIONS
  The physiological index, rho(max), will be a good index for assessing the adaptation process to visually induced motion sickness and may be useful in checking the safety of rehabilitation systems with new image technologies.
authors: Graduate School of Engineering, Tohoku University, Aoba 6-6-05, Aramaki, Aoba-ku, Sendai, 980-8579, Japan. sugita@yoshizawa.ecei.tohoku.ac.jp
authors: Norihiro
authors: N
authors: Sugita
authors: Makoto
authors: M
authors: Yoshizawa
authors: Makoto
authors: M
authors: Abe
authors: Akira
authors: A
authors: Tanaka
authors: Takashi
authors: T
authors: Watanabe
authors: Shigeru
authors: S
authors: Chiba
authors: Tomoyuki
authors: T
authors: Yambe
authors: Shin-ichi
authors: S
authors: Nitta
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009041:Motion Sickness / Q000209:etiology*; D010775:Photic Stimulation / Q000009:adverse effects*; D011674:Pulse; D011795:Surveys and Questionnaires; D013997:Time Factors; D014584:User-Computer Interface; D055815:Young Adult