Some syntactic determinants of sentential complexity

The perceptual complexity of three lists of self-embedded sentences was evaluated in terms of the accuracy and time required for their paraphrase. The lists differed by the presence of relative pronouns in one list, their absence in a second and by the addition of adjectives to the third. It was predicted that the presence of the relative pronouns would effect the only significant change in performance. In both auditory and visual presentations of the sentence lists, the presence of the relative pronouns proved to be facilitating, while the presence of the adjectives produced no significant changes.