A case-study of language-specific executive disorder

Executive control is recruited for language processing, particularly in complex linguistic tasks. Although the issue of the existence of an executive control specific to language is still an open issue, there is much evidence that executively-demanding language tasks rely on domain-general rather than language-specific executive resources. Here, we addressed this issue by assessing verbal and non-verbal executive capacities in LG, an aphasic patient after a stroke. First, we showed that LG's performance was spared in all non-verbal tasks regardless of the executive demands. Second, by contrasting conditions of high and low executive demand in verbal tasks, we showed that LG was only impaired in verbal task with high executive demand. The performance dissociation between low and high executive demand conditions in the verbal domain, not observed in the non-verbal domain, shows that verbal executive control partly dissociates from non-verbal executive control. This language-specific executive disorder suggests that some executive processes might be language-specific.