Researchers have highlighted cognitive deficits causing reading difficulties in people suffering from “neglect dyslexia” after surviving a stroke.
- A study has identified some of the different cognitive mechanisms that contribute to reading difficulties in people with left-sided “neglect dyslexia,” a condition that often follows right-hemisphere stroke.
- Left-sided “neglect dyslexia” is characterized by omissions of entire words on the left side of a page or by reading errors systematically involving the left portion of words.
- “Understanding the distinction between whole-word omission mechanisms and letter-in-word errors is crucial for developing more effective rehabilitation techniques, tailored to the specific deficits of each patient,” according to the researchers.
Following a stroke, survivors may have difficulty reading correctly, even going so far as to suffer from dyslexia. But how to explain it? A new study, published in the journal Experimental Brain Researchseems to have identified certain cognitive mechanisms underlying this problem, opening the way to new tailor-made interventions.
Ten stroke survivors with dyslexia subjected to reading tests
As part of their work, researchers from the Kessler Foundation and the University of Washington (United States) conducted two separate experiments with ten stroke survivors suffering from left-sided “neglect dyslexia”, which is characterized by omissions of entire words on the left part of a page or by reading errors systematically relating to the left portion of the words.
“Applied reading requires information processing of target words and peripheral words to generate precise gaze control”can we read in a communicated. When we read, in fact, we first fix our gaze on a key word, called a floveal word (directly in their line of sight), then we automatically fix the words which are adjacent to it, the parafoveal words.
In the first experiment, participants read the words presented in their parafoveal vision, with and without intrusion of distracting words. The second experiment repeated the task with the target words presented in their foveal vision. The goal was to determine whether reading errors originated from the position of the word relative to the reader (egocentric position) or from its position within a two-word frame (allocentric).
Three cognitive deficits contributing to “neglect dyslexia” after stroke
As a result, the study identified three distinct cognitive deficits that contribute to reading difficulties in people suffering from left-sided “neglect dyslexia” after a stroke. “Whole-word errors were influenced by the egocentric position of the word, with a significant number of errors occurring when distracting word intrusions occurred, but this effect disappeared when the target word was presented to them in their foveal vision, suggesting a deficit in egocentric spatial processing.explains Dr. Timothy J. Rich, lead author of the study.
He pursues : “Conversely, errors on letters on the left side of words remained consistent regardless of the spatial position of the word or the presence of distractor words, indicating an allocentric processing deficit within the word itself.”
Finally, the study revealed “a third deficit – a failure of selective attention – that resulted in whole-word intrusion errors. In the presence of distractors, individuals often reported the distracting word instead of the target word, a convincing demonstration of this deficit attention.”
Towards rehabilitation more adapted to the specificities of the patient
“This study is significant because it differentiates between the mechanisms of whole-word omissions and letter errors in words, which can often be confused with “neglect dyslexia,” concludes Dr. Rich. Understanding this distinction is crucial to developing more effective rehabilitation techniques, adapted to the specific deficits of each patient.”
