Perceptual span in individuals with aphasia.
Gayle DeDe
PMID 33041424WHAT IT FOUND
People with aphasia had a smaller visual span while reading.
Their reading speed matched full text only when they could see the fixated word plus one word to the right; controls needed at least two words to the right.
Key findings
01When people with aphasia could see only the word they were fixating on, their reading slowed. When they could see the next word to the right, their reading speed and fixation count matched the condition where the whole sentence was visible.
02Controls did not match the whole-sentence condition on fixation count until they could see two words to the right.
03Screening tasks showed people with aphasia could detect targets to the right and left of fixation, and the paper states that visual impairments alone do not account for the reduced span.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only 15 people with aphasia and 15 controls completed the study; four people with aphasia were excluded, and the paper reports 11 people with aphasia in later analyses. Four additional people with aphasia could not complete the study because of eye-tracking difficulty. Visual fields were not formally assessed by optometry, so a visual contribution cannot be fully ruled out. A programming error meant only seven controls completed the visual screening tests. Correlations between aphasia severity and the reading-rate difference between 1W and W+1 were not significant, likely because of the small sample. Trials with more than 10 blinks were kept because reading times were long, which may have inflated total reading times. One participant with aphasia was not aphasic by the Western Aphasia Battery but was included based on anomia. Controls had more years of education than participants with aphasia.
The easy way to misread this
Do not read the smaller span as proof of a right visual field cut. The screening tasks showed people with aphasia detected targets to the right and left, but visual fields were not formally assessed.