Abstract

We describe a patient RS with dementia of the Alzheimer’s type affecting memory, language and object recognition. RS displays well preserved knowledge of gestures and actions and he is able to name actions significantly better than he can name objects from visual input. These data confirm that action knowledge and object knowledge are dissociable skills in patients with dementia. We tested the hypothesis that action naming in dementia depends upon object knowledge by studying the effects of object knowledge on several action naming tasks. We found that RS’s ability to name actions depends on the relationship between the action name and his knowledge about objects. Instrumental verbs that do not require knowledge about tools to be named correctly (e.g. diving) were named significantly better than actions that do require knowledge about tools to be named correctly (e.g. hammering). This effect was independent of the imageability, frequency and age-of-acquisition of the verb. We argue that action naming for RS is constrained by his knowledge of objects. Specifically, if an action depends on knowledge of an object such as object movement, then naming is more likely to be impaired than naming of an action that does not depend on object knowledge. We propose an account of action naming in dementia that considers the conceptual associations between actions and objects, and we argue that these associations should be taken into account when testing for a noun/verb dissociation at all levels of deficit.