Conceptual processing of action verbs with and without motor representations.

Reading an action verb activates its corresponding motor representation in the reader's motor cortex, but whether this activation is relevant for comprehension remains unclear. To quantify the contribution of motor representations to the conceptual processing of action verbs, we measured the efficiency of two participants with atypical motor experience due to congenitally severely reduced upper limbs in processing verbs referring to actions that they had previously executed (e.g., writing) or not (e.g., shoveling) and compared the efficiency difference between the two verb categories to that found in typical participants, who had previously executed all these actions. This allowed measuring the contribution of motor representations unbiased by confounded low-level, lexical and semantic variables. Although the task was sensitive and the participants' performance was positively influenced by the richness of the words' conceptual representations, we found no detectable advantage for words associated with motor representations.