Visual Crowding

A perceptual phenomenon in which the presence of nearby flanking characters or objects makes it harder to recognise a target character, especially in peripheral vision or when the target is small, low-contrast, or briefly viewed. Crowding jointly with limited visual span sets an upper bound on reading speed and is a dominant factor in why text becomes unreadable under situational visual impairments such as motion, glare, or low resolution. Accessibility-relevant mitigations include larger font sizes, increased character and line spacing, higher contrast, and reduced ornamentation around individual glyphs.