Processing open and closed class-headed nonwords: left hemisphere support for separate vocabularies.

Evidence from studies of sentence production and comprehension points to a distinction between the open and closed class vocabularies. Data from the neurologically impaired suggest the left hemisphere selectively supports this distinction. This study further examines the vocabulary distinction by presenting to the different visual hemifields nonwords embedded with open or closed class portions, and asking normal subjects to make lexical decisions. Results indicate the vocabulary distinction is evident with RVF, but not LVF, presentations. This is discussed in terms of the use to which open and closed class words are put in sentence processing and also bears on the issue of the distinct cognitive styles associated with the different cerebral hemispheres.