Structural errors in normal and agrammatic speech

Abstract

Many errors in normal speech are best described as instances where the wrong morphological or syntactic structure is accessed. This often leads to the addition or loss of closed class lexical items. Structural substitutions are biased towards more frequent structures and towards minimal structures that are shared by many more elaborated structures. In English, both biases favour structures without closed class items, so that closed class items are more often lost than added. The loss of open class lexical items is qualitatively different, and is much less common. It is not necessary to assume that open and closed class lexical items constitute separate processing vocabularies. Broca's aphasics show a similar pattern of errors, known as agrammatism, that can be accounted for in the same fashion.