The Glenn A. Fry invited lecture. Accommodation to gratings and more naturalistic stimuli.

An array of stimulus characteristics, such as spatial frequency content, contrast, color, and size, as well as higher-level control aspects, such as cognitive demand, instruction set, and volitional effort, may influence the steady-state accommodative response. Several experiments are reviewed which demonstrate clearly the remarkable robustness of accommodation to marked variations in these parameters. The retinal luminance gradient appears to be the primary determinant of overall response accuracy. These findings are of theoretical interest in understanding basic aspects of accommodative control, as well as being of practical importance. They suggest that the accommodative response remains relatively stable and accurate despite dynamic changes in retinal-image quality which occur under experimental and clinical, as well as more naturalistic, viewing conditions.