Daniel Gabarró presents (in Spanish) a method that uses neurolinguistic to improve the learning of languages.
His hypotesis it's that some children and adults doesn't use visual memory to learn languages. When that happens, they used to use the auditory memory to know how to spell, increasing the spelling errors. To summarize: they need "to see" the words in their minds to learn.
The use of visual memory can be important as a meta-cognitive strategy that can help the cognitive process of learning for any person and any subject.