"I can write seven but I can't say it": a case of domain-specific phonological output deficit for numbers

While it is established that numbers represent a category-specific semantic domain being dissociable from other semantic domains, it is a debated issue whether the category-specific dissociability persists at a level of lexical processing or whether words and number words are processed by the same lexical mechanisms. In most of the documented cases of brain damage, lexical processing of words and number words was equally spared or impaired. Here, we describe the case of a patient who after recovering from his naming disorders, showed a selective deficit in the spoken production of numbers with spared number writing and number comprehension abilities. After having ruled out alternative interpretations, we can conclude that these results indicate that words and numbers are not only categorically organised at the semantic level but that they are also processed by different lexical mechanisms. In addition, the results argue in favour of the existence of different modality-specific output lexicons for the written and spoken production of numerals.