Processing of negative morphemes in aphasia: An example of the complexities of the closed class/open class concept

The distinction between open class and closed class items is frequently made in contemporary aphasia literature, but it is not always clear that the users of these terms have a full awareness of the linguistic complexity of the concept. This paper thus begins with an extended discussion of some of these complexities, using adverbs, prepositions, and derivational affixes as examples. The paper then describes an experiment which investigated one area of English where the open/closed distinction is unclear, the area of negation. On a sentence-anagram picture-matching task, 25 aphasic subjects (principally non-fluent) responded significantly more accurately when the word cards that they were given to work with contained a negative prefix, such as un-, than when the word set contained the word not. It is suggested that this somewhat unexpected result may be attributable to the close link between derivational prefixes and the open-class words to which they attach.