For both datasets, fixation durations greater than 800 milliseconds (ms) and less than 80 ms were excluded. Since we were only interested in landing site data involving single fixations resulting from progressive, rightward saccades, all other data were excluded from analysis. We excluded regressive saccades because they usually occur when the reader has difficulty with a sentence or phrase. On the other hand, we were interested in the processes underlying fluent reading. Beginning and end-of-line fixations were also excluded.
Figure 3. Landing site distributions for readers of a Thai short story as a function of launch distance and word length.
Figure 4. Landing site distributions for Chinese readers as a function of launch distance and word length. The graphs represent single fixations from rightward saccades on words of length one and two characters. Landing site positions are measured to a halfcharacter resolution.
Figure 1 shows the distribution of landing sites for Thai readers for near and far launches to words from length 3 to 7 inclusive. Launch distances were defined as near or far if they were less than or greater than the mean launch distance (4.3 and 2.7 for characters for Thai and Chinese, respectively). In the left panel, where the launch distance is greater than the mean, there is a pattern suggesting an underlying random process attenuated by the central tendency of the saccade amplitude distribution. In the right panel there appears to be a peaked distribution, suggesting a more deliberate targeting of word centres.
Figure 2 shows a similar pattern for Chinese data for words of length 1 and 2 (there were not enough data points for length 3 words to be plotted). Note that the landing sites are plotted in half-characters along the x-axis to give a clearer visualisation of the landing site distributions.