The Word Frequency Effect on Reading in Typically Developing Children and Children with ADHD: An Eye-Tracking Study

Objectives: Eye-movement tracking is of great interest in studies not only on young children but also on individuals experiencing reading difficulties. The present study examines the eye movements of children with attention deficit/hyperactivity disorder (ADHD) as well as those of typically developing children. It is anticipated that eye-movement studies will significantly inform our understanding of the underlying deficits that may contribute to reading difficulties in children with ADHD. Methods: Eleven ADHD children and 11 control subjects participated in this study. All participants were in grades 4 to 6 in school. They were asked to silently read a collection of sentences embedded with controlled frequency (high/low) target nouns. Their eye movements were measured while they read. Results: Eye movements revealed significant word frequency effects in both groups, fixation duration (first fixation time, single fixation time, gaze duration), and an increased number of fixations for low-frequency words. Consistent with previous research, the children in the ADHD group displayed slightly longer fixation duration and made a greater number of fixations compared to the children in the control group; however, there were no group differences as well as interaction for frequency with the group factor. Conclusion: These results, especially the frequency effect found in both groups, are discussed in the context of previous studies.