Saccades:
When you move your head and eyes to scan a scene, your eyes are incapable of moving smoothly across it and seeing everything. Instead, you see in the image in a series of very quick jumps (called saccades) with very short pauses (called fixations) and it is only during the pauses that an image is processed.
Your brain fills in the gaps with a combination of peripheral vision and an assumption that what is in the gaps must be the same as what you see during the pauses. [“What an RAF pilot can teach us about being safe on the road,” LondonCyclist]
[h/t Chris Johnson]
