Abstract Psychophysical and electrophysiological studies of animals and humans provide firm evidence that a meridional resolution deficit (meridional amblyopia), present in some astigmats. results from selective visual exposure. The link between orientational differences in acuity and visual experience suggests that similar inequalities might also be present in the accommodation system. Measurements of steadystate accommodative responses to targets containing contours of different orientations have been made on non-astigmatic and astigmatic subjects. The visual resolution of certain subjects has also been determined. Prominent differences are found in the results for the two groups. When resolution is superior for detail of a given orientation, that orientation tends to control accommodation. These results suggest that the pathways subserving accommodation are subject to experimental modification.