The development of vernier acuity in human infants aged 2-9 months was assessed by a preferential looking procedure using a vernier-motion display. The displacement of vernier offsets gives the impression of motion only when the vernier offsets are detected. Grating acuity of the same group of infants was also measured by a preferential looking procedure. Vernier acuity was found to be superior to grating acuity only after 3 months of age. This superiority of vernier acuity was compared with the superiority of stereoscopic acuity to grating acuity. The two classes of hyperacuity proved to be almost equivalent in terms of their developmental time-courses. A common physiological basis for the development of hyperacuities is suggested.