In this study, two similar depth perception experiments were conducted to investigate 3-month-old infants' perception of changes in depth while they were being moved. In the first, the subjects, 18 infants (80 to 105 days old) were lowered face down towards the textured floor of a 3-sided enclosure (visual crib). Three experimental conditions were used: babies were lowered until their heads were (1) in contact with the floor, (2) 10 cm. from the surface, and (3) 20 cm. from the surface. Head rotation occurring prior to any contact with the surface was considered withdrawal. In the second experiment, 8 infants (90 to 104 days old) were observed in three different stages of motion: (1) contact as in Experiment I, (2) approach to 20 cm. With a sharp deceleration at the end of the movement, and (3) horizontal motion near the surface of the crib. The procedure was similar to Experiment I except for the conditions of locomotion. Videotape recordings were made in both cases. Results indicated that infants perceive changes in depth during their own displacement, as the contact condition produced the greatest frequency of head withdrawal in both the experiments. (CM)