After an extensive transformational consideration of the shift of indirect objects with "to" and "for," the authors introduce a theory of perceptual strategy which could be used to supplement transformational theory. According to a concept of perceptual strategy constraints on susceptibility, the strategy for interpreting a sentence involves making hypotheses about the deep structure of the sentence on the basis of the amount of the sentence heard up to a given point. This is first illustrated with relative clauses and is then applied to dative movements. In such an interpretation, the essential task is to find out which constituents have been moved out of their deep structure position and in what deep structure position they originated. This approach appeals to linguistic performance and maintains the distinction between the rules of grammar and how the rules are used by speaker or hearer to interpret sentences. (Author/VM)