PubMed1984
We found, not surprisingly, that most nonretarded adults can either give accurate and adequate sets of directions to their places of residence or recognize their inability to do so and refuse to attempt to give any--86% of those in our sample. We found also that this is the case for many mentally retarded adults who reside in the community--45% of those in our sample. These individuals responded in perfectly appropriate ways to a request for directions. However, 55% of the mentally retarded sample gave inaccurate or ineffective directions. Of these, 64% made errors that differed in quantity--both in terms of total number of errors and number of errors per set of directions--but not in kind from the errors made by the nonretarded sample. This leaves 13 mildly mentally retarded individuals--20% of our total sample, 36% of those who gave inaccurate directions--who made errors that were unlike those made by nonretarded adults: errors of communicative competence that involved a lack of knowledge of the structure and function of directions or a lack of ability in communicative design. In our studies of other everyday speech events such as narratives, we have suggested that one of the reasons for the impression interlocutors have that something is different or wrong with the way that mildly mentally retarded persons speak is that although they make the same sorts of errors that nonretarded speakers make, they make them more frequently. Because of the nature of the speech events we have studied, we have been unable to demonstrate this conclusively. However, as we pointed out at the beginning of this paper, the nature of directions is such that one can make objective judgements of accuracy and of type and number of errors. For this speech event at least, our suggestion that mildly mentally retarded speakers make errors that are like those made by nonretarded speakers but make them more frequently, is confirmed. Furthermore, we have found that difficulties with communicative design that are not usually exhibited in the speech of nonretarded persons are present not only in the narratives of mentally retarded speakers but in the directions that they give as well. Traditionally, studies of language and mental retardation have concentrated on subjects' phonological, morphological, lexical, and syntactic deficits. But for the mildly retarded, such deficits are relatively insignificant.(ABSTRACT TRUNCATED AT 400 WORDS)