Untangling letter confusability and word length effects in pure alexia

Pure alexia is an acquired neuropsychological disorder that follows damage to the occipito-temporal lobe. This brain damage results in a severe reading impairment in which previously literate individuals are no longer able to efficiently read words, but are still able to perform other language tasks. The present study sought to identify factors of words that make it more difficult for pure alexic individuals to read, such as letter confusability and word length. Eye-tracking methodology was paired with a naming task to examine whether word length or letter confusability is a better predictor of processing difficulty. It was found that word length was a significant predictor of reading time, while summed letter confusability was not significant. This study contradicts some previous research and shows that when an orthogonal set of stimuli is used, letter confusability is not a significant factor driving this reading impairment in all individuals with pure alexia.