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Focus conflict can occur in [[virtual reality]] devices, [[augmented reality]] devices, and binocular flat focus autostereoscopic displays.
Focus conflict can occur in [[virtual reality]] devices, [[augmented reality]] devices, and binocular flat focus autostereoscopic displays.
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When a human views the real world, vergence and focus distances typically match, and the human visual system has evolved to expect this.
Fixed-focus biscopic displays have a fixed focus distance, but the vergence distance can change widely, resulting in a mismatch. The human visual system has not evolved to view these types of artificial 3D images comfortably. Focus conflict can be a very unpleasant sensation for the viewer.<ref>{{Cite journal |title=The zone of comfort: Predicting visual discomfort with stereo displays |url=https://jov.arvojournals.org/article.aspx?articleid=2121032 |journal=Jov ArvoJournals |volume=11 |issue=8}}</ref><ref>{{Cite journal |last1=Wann |first1=John P. |last2=Mon-Williams |first2=Mark |date=May 1997 |title=Health issues with virtual reality displays: what we do know and what we don't |url=https://dl.acm.org/doi/10.1145/271283.271307 |journal=ACM SIGGRAPH Computer Graphics |language=en |volume=31 |issue=2 |pages=53–57 |doi=10.1145/271283.271307 |s2cid=17366319 |issn=0097-8930}}</ref><ref>{{Cite journal |date=March 2008 |title=Vergence–accommodation conflicts hinder visual performance and cause visual fatigue |url=https://jov.arvojournals.org/article.aspx?articleid=2122611 |journal=JOV Arvo Journals |volume=8 |issue=3}}</ref>
Fixed-focus biscopic displays have a fixed focus distance, but the vergence distance can change widely, resulting in a mismatch. The human visual system has not evolved to view these types of artificial 3D images comfortably. Focus conflict can be a very unpleasant sensation for the viewer.<ref>{{Cite journal |title=The zone of comfort: Predicting visual discomfort with stereo displays |url=https://jov.arvojournals.org/article.aspx?articleid=2121032 |journal=Jov ArvoJournals |volume=11 |issue=8}}</ref><ref>{{Cite journal |last1=Wann |first1=John P. |last2=Mon-Williams |first2=Mark |date=May 1997 |title=Health issues with virtual reality displays: what we do know and what we don't |url=https://dl.acm.org/doi/10.1145/271283.271307 |journal=ACM SIGGRAPH Computer Graphics |language=en |volume=31 |issue=2 |pages=53–57 |doi=10.1145/271283.271307 |s2cid=17366319 |issn=0097-8930}}</ref><ref>{{Cite journal |date=March 2008 |title=Vergence–accommodation conflicts hinder visual performance and cause visual fatigue |url=https://jov.arvojournals.org/article.aspx?articleid=2122611 |journal=JOV Arvo Journals |volume=8 |issue=3}}</ref>