Explanation
Persistence refers to how long a pixel remains illuminated on the display between frame refreshes. High persistence means pixels stay lit for the entire frame duration, causing motion blur and ghosting when the user turns their head. Low persistence -- the standard in modern VR headsets -- briefly flashes each frame and then goes dark, dramatically reducing blur and improving visual clarity during rapid head movements.
Real-world example
A display that keeps pixels lit too long creates blurry trails during fast movements.
Practical applications
- Reducing motion blur during rapid head rotations
- Improving text and detail sharpness
- Preventing unpleasant visual artifacts
- Optimizing visual comfort for extended sessions
Persistence and display technologies
Full persistence (standard LCD)
- Pixels lit 100% of the time between frames
- Major cause of motion blur
- Visible ghosting on edges
- Problematic for fast VR movements
Example: A standard office monitor where fast movements appear blurry
Low persistence (modern VR)
- Pixels lit for only a fraction of the frame
- Brief flash followed by a black screen
- Drastically reduces motion blur
- Standard in all current VR headsets
Example: VR headset displays show each image for only 2-3 ms per frame
Rolling shutter vs global
- Global: all pixels update simultaneously (ideal)
- Rolling: line-by-line refresh
- Impact on VR visual clarity
- OLED generally outperforms LCD
Example: OLED displays in the Valve Index headset with near-zero persistence
VR scenario
In VR, when you quickly turn your head, old high-persistence displays created phantom trails: text became unreadable, edges doubled. Modern headsets use low persistence: each image is displayed for only 2 ms, then the screen goes black. Your eye does not perceive the darkness thanks to the high refresh rate, but the blur vanishes.
Why it matters in professional VR
- Visual comfort: persistence causes eye fatigue and nausea
- Readability: text and interfaces remain sharp even during movement
- Presence: blur breaks the illusion of reality
- Ongoing innovation: manufacturers continue to reduce persistence further