Visual processing in adults with dyslexia is determined by duration of fixation periods

Joyce Chen ’23

Figure 1: Increased eye movements in individuals with dyslexia were hypothesized to be caused by a deficit in visual processing in reading.

Our fascinating ability to read is often overlooked and taken for granted. Reading requires a high level of cooperation between the eyes and the brain. The eyes are immediately able to formulate words and meanings out of the letter combinations by pausing over the text. This pause is a vital part of reading. Dyslexia is a condition in which individuals have difficulty reading and processing words and sentences. A particular subcategory of dyslexia involves a deficiency in visual processing due to an increased amount of eye fixations during reading. Dr. Léon Franzen of Concordia University and a group of researchers took the initiative to study the underlying mechanisms of this subcategory of dyslexia in adults.

The research team studied a total of 67 subjects consisting of 35 adults with dyslexia and 32 adults without it. They hypothesized that the participants with dyslexia would read at a slower pace and exhibit a greater number of eye movements such as longer fixations and shorter saccades, which are rapid movements in between fixations. An eye-tracking device was used to locate and analyze the duration of eye movements of all participants during the study. During the study, the participants were instructed to complete several tests in which text was displayed on the screen at certain intervals. After reading the text, the participants had to answer a multiple choice question based on what they had just read. The results of the study confirmed the team’s initial hypotheses. Furthermore, individuals with dyslexia had much shorter saccades and often fixated over words for long periods of time. This is due to a lack in lexical processing, which is the cognitive encoding event that occurs when reading. 

Dr. Franzen and his research team’s study provides additional information on visual processing in adults with dyslexia. Future experimental studies should be conducted to further investigate the causal relationship between cognitive processing and dyslexia. 

Works Cited:

[1] L. Franzen, et. al., Individuals with dyslexia use a different visual sampling strategy to read text. Sci Rep 11, 6449 (2021). Doi: 10.1038/s41598-021-84945-9x

[2] Image retrieved from: https://images.pexels.com/photos/4132936/pexels-photo-4132936.png?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260

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