‘I see colors when I touch them’. Color agnosia with visuo-tactile facilitation in a patient with posterior cortical atrophy

Abstract We describe the case of a 69-year-old male with posterior cortical atrophy (PCA), who had a severe cognitive impairment with prominent visuospatial and visuoperceptual deficits, and a degradation of semantic knowledge of colors. A detailed neuropsychological evaluation was performed. On color naming test, his performance improved when he could touch and manipulate the object (visuo-tactile facilitation). Interestingly, his performance in this task improved even with abstract objects, which had identical shape, therefore not increasing the chance of being of a particular color. We discuss several mechanisms that could account for this unexpected finding, proposing the fascinating hypothesis that haptic object exploration facilitated color perception trough a cross-modal information processing.