Word difficulty determines the accuracy of regressive saccades in reading.

The current experiment was conducted to study effects of lexical word difficulty on the control of long-range regressive saccades. Participants read single line sentences in German for comprehension and checked for a spelling error that was inserted when the eyes had reached the end of the line. When words were more difficult in terms of orthographic irregularity and lower frequency, this dramatically increased the accuracy of regressions back to these words. If the target was missed, fewer additional saccades and less time were needed until the eyes fixated the target word. The data suggest that more effortful word processing is related to a better representation in visual-spatial memory, enabling more effective programming of regressions.