The influence of text difficulty level and topic on eye-movement behavior and pupil size during reading

This paper aims to show how some eye-tracking variables during reading are affected by various major factors, including individual differences, the difficulty level of the text, and the topic of the text. For this purpose, we conducted an eye-tracking experiment with 21 subjects who read six passages with different topics. For each subject, changes in three variables were evaluated: the mean fixation duration, the pupil size, and the average speed of reading. The Flesch reading ease score is employed as a measure for the difficulty level of the text. Analysis of variance is used in order to analyze determinant factors associated with text characteristics, including the difficulty level and the topic of the text. The analysis results are summarized as follows: During the reading of passages with similar difficulty levels, the topic of the text has no significant effect on mean fixation duration and mean pupil size, whereas a significant influence on average speed of reading is observed. Furthermore, individual characteristics have a major impact on eye-movement behavior. The results of this study can be applied in various areas such as the assessment of mental workload, information processing, and personalized interfaces.