From word superiority to word inferiority: Visual processing of letters and words in pure alexia

Abstract

Visual processing and naming of individual letters and short words were investigated in four patients with pure alexia. To test processing at different levels, the same stimuli were studied across a naming task and a visual perception task. The normal word superiority effect was eliminated in both tasks for all patients, and this pattern was more pronounced in the more severely affected patients. The relationship between performance with single letters and words was, however, not straightforward: One patient performed within the normal range on the letter perception task, while being severely impaired in letter naming and word processing, and performance with letters and words was dissociated in all four patients, with word reading being more severely impaired than letter recognition. This suggests that the word reading deficit in pure alexia may not be reduced to an impairment in single letter perception.

Keywords:

• Letter-by-letter reading
• Letter perception
• Word length effect
• Word reading

We thank Alexander Leff and Egill Rostrup for supplying the description of LK's lesion. Thanks to Mark Ruby and Felicia Kettelz for collection the normal data in Study 1, Ida-Marie Arendt for collecting the control data for Study 2, and Fakutsi for standing by.The study was supported by a grant to R.S. from the Danish Research Council for Independent Research (Sapere Aude) [grant number 11-115958].

Notes

¹ It should be noted here that very few experimental studies have investigated the WSE in the context of RTs to unmasked words. Following Cattell's (1886) original observation of faster RTs to words than letters, this finding has received relatively little attention compared to the corresponding effect in accuracy (e.g., Reicher, 1969; Johnston, 1981; Seidenberg & McClelland, 1981; Wheeler, 1970). Thus, although the effect on RTs was robust in our Danish control group, the circumstances (subject, age, language, word characteristics, word lengths, etc.) under which the word superiority effect can be observed in response time remains to be determined (see Starrfelt, Petersen, & Vangkilde, 2013).