That way, the researchers can see if the self-identified verbal learners really learned better when the information was just spoken aloud, for example.
Reading a phrase like, Oh shut up in a text, instead of hearing it spoken aloud, makes it easy to misunderstand the speaker's intention - their aim, or plan of what they want to do.
Like increasing the amount of text you process during each fixation, flashing words in one spot rapidly, and eliminating “subvocalization” – that voice that reads “aloud” in your head when you read silently.