Persistence of vision

Your eye stores an image for about 100 to 150 milliseconds after the actual stimulus — this is called persistence of vision. On set and in the edit, you utilize this neurological phenomenon daily without consciously thinking about it. At 24 frames per second, your brain doesn't see slides, but continuous motion. This blending between successive frames is the foundation of all your filmmaking work.

For a long time, this principle was considered to fully explain the flicker-fusion phenomenon — the threshold at which the eye perceives individual light flashes as continuous brightness. However, modern neuroscience has differentiated this: the pure "afterimage function" only explains part of the phenomenon. Your visual system works much more actively; it fills in gaps through prediction and pattern recognition. Nevertheless, the term remains helpful because it reflects practical reality — you cut a sequence because this neurological concatenation works, not because you need to understand the exact neurobiological cascade.

This becomes concretely relevant with flicker effects. If you shoot with a camera at 50 Hz and your monitor runs at 60 Hz, moiré patterns emerge — not because persistence fails, but because the frame rates collide. You adjust the shutter speed precisely to avoid this effect. With motion graphics or rapid cutting sequences, you intuitively calculate: a frame must remain visible for 16.67 milliseconds (at 60fps) for the eye to register it. Below that, it becomes too fleeting, cuts become "choppy."

The old explanation of persistence is therefore not wrong — it's simply incomplete. Your visual apparatus is not a passive storage unit, but a predictive system. However, the measurements — the time thresholds at which motion appears fluid — remain valid. That's why 24fps still works for cinema. That's why you suddenly need 90fps for VR applications to avoid motion sickness: your system then engages other perceptual mechanisms, not just visual persistence.