Dimensions of Text Complexity in the Spoken and Written Modes: A Comparison of Theory-Based Models

In many studies, grammatical complexity has been treated as a single unified construct. However, other research contradicts that view, suggesting instead that the different structural types and syntactic functions of complexity features are distributed in texts in fundamentally different ways. These patterns have been documented in general corpora that include a wide range of spoken and written registers. One question that has not been fully addressed is whether grammatical complexity features are organized in the same ways in the spoken versus written modes. The present study tests the empirical adequacy of four competing models based on different theoretical conceptualizations of text complexity, comparing their goodness-of-fit in spoken versus written modes. The results show that text complexity must be treated as a multi-dimensional construct; dimensions that combine structural type and syntactic function provide the best account of the actual patterns of linguistic co-occurrence. To a large extent, the same complexity dimensions operate in both the spoken and written modes. Two of these dimensions—dependent phrases functioning as noun modifiers and finite dependent clauses functioning as clause-level constituents—represent the strongest co-occurrence patterns. In addition, these two dimensions operate in complementary distribution, in both the spoken and written modes. Overall, though, these two dimensions are shown to represent stronger co-occurrence patterns in the written mode than in the spoken mode.