Eye-movement study during visual search in Chinese children with developmental dyslexia.
BACKGROUND
Developmental dyslexia (DD) is a disorder in which children with normal intelligence and sensory abilities show learning deficits in reading. Abnormal eye movements have been found in DD. However, eye-movement abnormalities during visual search among Chinese children with DD remain unknown. We aimed to identify the eyemovement characteristics and search efficiency of Chinese children with DD during visual search for targets of different conceptual categories, under same-category conditions.


METHODS
We compared 32 Chinese dyslexic children and 39 non-dyslexic children in visual search tasks, which were assessed using EyeLink II High-Speed Eye Tracker (SR Research Ltd., Canada). Letters, single Chinese characters, digits, Chinese phrases, figures and facial expressions were used as stimuli. Targets were similar to distractors in meaning, phonology and/or shape.


RESULTS
A main effect of task on visual search scores and all eye-movement parameters were found. Search scores, average saccade amplitude and saccade distance were significantly smaller in the DD group than in the controls. An interaction between group and task was found for pupil diameter.


CONCLUSIONS
Unlike normal readers, children with DD had a reduction in the visual attention span and search accuracy. Besides, children with DD could not increase their mental workload with increase in task difficulty. The conceptual category of the stimulus materials significantly impacts search speed, accuracy and eye-movement parameters.
Faculty of Maternal and Child Health, Preventive Medicine Institute, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
Xiu-Hong
XH
Li
Jin
J
Jing
De-Sheng
DS
Yang
Hui
H
Wang
Qing-Xiong
QX
Wang
Shan-Shan
SS
Song
Fang
F
Fan
D000293:Adolescent; D044466:Asian People; D002648:Child; D004410:Dyslexia / Q000503:physiopathology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male