A three-dimensional optometer (TDO), which can measure simultaneously three major ocular functions in a working environment, was used to measure the visual responses of human subjects viewing: (1) actual artworks and (2) corrugation presented by moving random dots on a cathode ray tube (CRT). Measurements were performed in natural viewing conditions on two emmetropic females. Both subjects demonstrated distinct accommodative responses for the stimuli presented at a fixed distance. The results indicate that the accommodation generally shifts in accord with changes of perceived distance. The usefulness of the TDO was demonstrated in these experiments.