Crowding and eccentricity determine reading rate.

Bouma's law of crowding predicts an uncrowded central window through which we can read and a crowded periphery through which we cannot. The old discovery that readers make several fixations per second, rather than a continuous sweep across the text, suggests that reading is limited by the number of letters that can be acquired in one fixation, without moving one's eyes. That "visual span" has been measured in various ways, but remains unexplained.

Flicker flutter: is an illusory event as good as the real thing?

Verghese and Stone (1995) showed that reducing the perceived number of objects by grouping also reduces objective performance. Shams, Kamitani, and Shimojo (2000) showed that a single flash accompanied by multiple beeps appears to flash more than once. We show that objective orientation-discrimination performance depends solely on the perceived number of flashes, independent of the actual number of beeps and flashes.