Eye-movement Patterns of Chinese Children with Developmental Dyslexia during the Stroop Test

Objective To compare the eye-movement patterns of Chinese children with developmental dyslexia (DD children) with those of non-dyslexic children as they perform the Stroop Color and Word Test (SCWT), and to explore the relationship between their eye-movement patterns and interference effect. Methods An EyeLink II was used to record the eye-movement parameters of 32 DD children and 37 non-dyslexic children as they performed the SCWT. The independent samples t-test and repeated measures were used to analyze behavioral and eye-movement parameters. Results Compared to the control group, Chinese DD children presented lower accuracy (F = 8.488), slower response time (F = 25.306), and larger interference effect (t = 2.29); Chinese DD children also exhibited lower frequency of fixations (F = 6.069), greater numbers of saccades (F = 7.914) and fixations (F = 5.272), and shorter mean saccade distance (F = 4.03). All behavioral and eye-movement parameters differed significantly among the three tasks in the SCWT. There was significant interaction between groups and tasks in accuracy (F = 5.844), and marginally significant interaction in response time (F = 3.040). Chinese DD children tended to have lower accuracy and longer response time than the control group in the 'color-word naming' task. Conclusion Compared to non-dyslexic children, Chinese DD children are subject to a stronger interference effect. When performing the SCWT, Chinese DD children exhibit abnormal eye-movement patterns, namely shorter mean saccade distance, lower frequency of fixations, and more fixations and saccades. These abnormal eye movements may be relatively stable oculomotor patterns of DD children performing visual processing, and not influenced by impaired interference effect.