The planning of refixation saccades in reading.

The planning of the refixation saccade, i.e. the second saccade on 9- and 11-letter-strings, was assessed in two reading experiments that examined the influence of a length change at different times during the first fixation on a letter string. The results showed that the saccadic system was able to modify the first motor program if the new length information was available 150-190 ms before the execution of the refixation saccade. Moreover, the amplitude of the refixation saccade was found to be planned as a constant movement relative to the length of the item, regardless of the position of the initial fixation on the item. Finally, the refixation saccade seems to be preprogrammed before the primary saccade, depending on the length integrated at that time. Overall, these results suggest that the refixation saccade is programmed on the basis of the intrinsic properties of the item, such as its length.