Recovery process of colour naming defects in pure alexia - A five year longitudinal experimental study

The present study investigated the recovery process of colour naming defects and the ability for matching seen colour to colour name given verbally (colour pointing) in a patient with pure alexia (M.S.). The recovery process of the patient's ability to process the physical parameters involved in colour information processing was also examined. To look at how M.S. processed the physical parameters, the similarity judgment tasks of internal representation of colour generated by verbal and visual stimuli were employed. While colour pointing ability became practically normal 22 months postonset, colour naming defects took longer to recover. The analysis of the results of similarity judgment using multidimensional scaling revealed that: (1) verbal stimuli generated consistently more stable internal representation of colour than visual stimuli; and (2) colour information processing of M.S. altered 'hue with lightness' dependent to more 'hue' dependent in the 5 years since the onset of illness. The underlying neuropsychological mechanism was discussed for these findings.