, 1998a and Behrmann et al., 1998b). One observation regarding both the general visual account of LBL reading is that the evidence base is largely associative in nature; that is, most studies claim that the co-occurrence of the characteristics of LBL reading (i.e., accurate but slow reading, with prominent word length effects) and a particular deficit (e.g., impaired perception of non-lexical stimuli) confers support for their chosen position. In addition, proponents of the general visual impairment account

have claimed support for their position from control brain-damaged patients who show the complementary association BIBF 1120 of no perceptual deficit and no impairment of reading (e.g., patient OL; Mycroft et al., 2009). By contrast, in the current study it is argued that such evidence does not prove a causal link between general visual deficits and LBL reading behaviour. This is achieved by presenting evidence from two patients who exhibit profound visual dysfunction in the presence of accurate and rapid word reading. Rather

than demonstrating a selective impairment to the visual word form system in the absence of general visual dysfunction, these patients’ reading abilities are remarkably preserved despite grave and diffuse selleck impairments to their visual system. The two patients reported in this study have a diagnosis of posterior cortical atrophy (PCA), a neurodegenerative condition involving progressive visual impairment in contrast to relatively spared memory functions. The most frequent underlying pathology is Alzheimer’s disease (AD), with PCA patients showing a greater

distribution of senile plaques and neurofibrillary tangles in posterior regions of the parietal cortex, the occipital cortex and temporo-occipital junction relative to more anterior cortical areas (Rogelet et al., 1996; Ross et al., 1996; Tang-Wai et al., 2004). Characteristic symptoms of PCA include early visual 2-hydroxyphytanoyl-CoA lyase processing deficits, and disorders of higher-order visuoperceptual and visuospatial processing (Benson et al., 1988; Mendez et al., 2002; Tang-Wai et al., 2004). Reading difficulties are often a prominent feature of PCA, occurring in about 80% of patients (Mendez et al., 2002) and studies on reading ability in PCA have identified a range of deficits, including neglect dyslexia (Mendez and Cherrier, 1998), attentional dyslexia (Saffran and Coslett, 1996), LBL reading (Catricala et al., 2011) and spatial alexia (Crutch and Warrington, 2007). The main aim of this study was to evaluate the hypothesis that general visual dysfunction necessarily leads to LBL reading. The general visual account predicts that basic visual impairments should be associated with slow, inefficient reading, with prominent word length effects characterised by considerable increases in reading latency with each additional constituent letter.