The tilt after-effect: changes with stimulus size and eccentricity.

Previous evidence that the tilt after-effect (TAE) is larger when the stimuli are viewed peripherally rather than centrally was confirmed. An increase in viewing distance also increased TAE size. However, the increase in the TAE in peripheral vision was abolished if stimuli were increased in size to compensate for the change in the cortical magnification factor. Both the decrease in field diameter and increase in spatial frequency with viewing distance were found to influence the size of the TAE. When the data were expressed in cortical terms, the TAE was found to increase with spatial frequency, and decrease with field diameter, regardless of retinal position. The functional significance of these effects is discussed.