The development of vernier acuity in infants.

Vernier and grating acuity were measured in infants up to 6 months of age using a two-alternative forced-choice preferential looking technique. Vernier resolution was measured using a horizontal vernier grating. The grating was presented on half of the screen while the other half contained horizontal lines which were continuous with the vernier grating. Movement artifacts were eliminated by making both halves of the display move as the offsets were introduced in half of the display field. Vernier acuity, like grating acuity, improved about 3 octaves over the first 6 months of life. Moreover, the vernier resolution of infants, as of adults, was better than grating resolution.