Abstract Measurements of the way the oculomotor system adapts to prisminduced heterophorias have been made in eight normal subjects. Adaptation to 2&dgr; vertically and, on separate occasions, to 6&dgr; horizontally was found to be substantially completed after only 2‐3 minutes of binocular visual experience. The form of the adaptive process for distant targets was asymmetrical in the horizontal meridian, being faster after the insertion of 6&dgr; base‐out than for 6&dgr; base‐in. This asymmetry largely disappeared for near vision.