Influence of foveal distractors on saccadic eye movements: a dead zone for the global effect.

Three experiments investigated the global effect with foveal distractors displayed in the same hemifield as more eccentric saccade targets. Distractors were x-letter strings of variable length and targets corresponded to the central letter of letter strings (e.g., 'xxxkxxx'). Results showed that only foveal distractors longer than four letters (about 1 degree) deviated the eyes in a center-of-gravity manner thus suggesting a dead zone for the global effect. Short distractors influenced the likelihood of small-amplitude saccades (less than about 1 degree) and the latency of longer saccades. The findings were interpreted based on the dissociation between fixation and saccadic neurons. Implications for eye movements in reading were discussed.