Distribution-dependent saccades in children with strabismus and in normals.

To guide saccades accurately human adult subjects learn rapidly to aim, in advance, for the central position of the distribution of the target positions studied. This causes a bias called range effect, i.e., saccades to the central location are accurate while the less eccentric locations are overshot and the more eccentric locations are undershot. It is believed that this is a cognitive strategy allowing to reduce overall variability. We show here that the same exists for normal children (5-13 years old). Most importantly, from the age of 5 years, children with strabismus use the same cognitive strategy despite the fact that their eyes are misaligned. Importantly, both eyes follow this strategy even though only one eye is fixating the target (the other eye being squinted).