A Single case study of 'letter-by-letter' reading

This paper presents a single case study of a 47-year-old man, BML, who, following a left occipito-temporal CVA, presented with a complete inability to recognise letters or read words aloud, in the context of preserved writing. As his letter recognition improved over time he demonstrated the characteristic features of ‘letter-by-letter reading’ (pure alexia), including a marked effect of number of letters on performance. In addition, however, he showed some preserved ‘covert’ knowledge of words he was unable to read aloud. He performed better than chance at lexical decision and provided semantic information for words that he was unable to read aloud correctly. Moreover, unlike previous cases in the literature this ‘covert’ recognition was NOT dependent on brief presentation of the stimulus. This paper documents detailed investigation of the nature of BML‘s impairment, including visual processing, lexical and semantic effects on reading over time. The implications of these data for theoretical accounts of pure alexia will be discussed.2 page(s