A structural account of phonological paraphasias.

The aim of this study is to develop a partial theory of phonological paraphasias which has some cross-syndrome and cross-linguistic validity. It is based on the distinction between content and structural units and emphasizes the role of the latter. The notion of structure holds the key to an understanding of the differences among the following three types of data: slips of the tongue, slips of the pen (defined as errors committed by healthy, competent adults), and paraphasias. A comparison of these three data types reveals that slips of the pen and paraphasias display striking similarities whereas slips of the tongue stand apart. This pattern emerges very clearly in an analysis of nine empirical effects all of which are found to be of a structural nature. On the basis of these results, it is argued that both the written output of normals and the oral output of aphasics are generated under a reduced structural representation (i.e., weak activation of structural nodes). However, the reasons for the diminished sensitivity to structure are not the same in the two modalities. While the impoverished structural representation is a likely consequence of the relatively slow production rate in writing, it may stem from an impaired transmission of activation among structural nodes in aphasia. By contrast, the normal speaking process occurs under the sway of a full-fledged structural representation. Hence, slips of the tongue are highly sensitive to structural effects.