In this paper we describe an experiment in sentence processing which was intended to relate two properties of syntactic structures that have received much discussion in linguistics and psychology (see references cited in the next section). First, some syntactic structures, such as the passive construction, require more processing effort than corresponding structures which express the same grammatical relations. Passive sentences in particular have been the subject of much experimental work. Second, it is clear, as was observed by Jespersen (1924), that the difference between active and passive sentences has something to do with focus of attention on a particular constituent, the grammatical subject. And the consequences of the difference of focus of attention is in some way related to the context formed by the discourse in which the sentence occurs. In this experiment we wanted to study syntactic structures which might have similar properties to the passive/active construction, so as to define exactly what features of passive sentences are responsible for their observed greater processing demands and definition of focus of attention, or sentence topic. One of the bases of the experiment, underlying the hypotheses we wanted to test, is that processing load and definition of sentence topic are related in some way.

We combined sentences exemplifying five different syntactic constructions with context sentences having different relations to the target sentences, and measured reaction time for reading and understanding the second or target sentence. The results show that there is a fairly consistent relationship of processing load for the other constructions as well as passive, and that overall processing time is sensitive to both syntactic structure and contextual information.