Word-Superiority in Pure Alexia

Pure alexia is an acquired reading disorder where patients lose the ability to read fast and fluently, but are commonly able to identify words letter-by-letter. This is evidenced by a pronounced word-length effect in reading, where reaction times (RTs) increase linearly with word length. The severity of the reading deficit in pure alexia has been reported to be systematically related to performanceon lexical and semantic decision tasks [1] and to visuoperceptual deficits [2]. Lesions to the suggested ‘visual word form area’ (VWFA) located in the left mid-fusiform gyrus seem to be of particular importance in causing pure alexia [3,4]. In the current study, we examine the word superiority effect (WSE) in four pure alexic patients. The WSE refers to the phenomenon that normal readers are better at identifying letters embedded in words than in letter strings [5]. The effect is typically found in experiments where stimuli are presented briefly and then masked, followed by either a forced choice or free report task. There are a few case studies of the word-superiority effect in pure alexia (e.g. [6]) but findings so far have been contradictory. There have been no systematic attempts at linking performance in WSE experiments to visuoperceptual abilities or severity in pure alexia.