Patterns in the structure of interaction and the functions of communication The research involving school age children shows similar general results to that including

younger children. Studies have found that adults (caregivers and teachers) produced mainly initiating moves, while children produce a high proportion of responses (Basil, 1992; Harris, 1982; Jollefif et al, 1992; Light et al, 1985a; Udwin & Yule, 1991). This suggests that the adults choose the topics of conversation, controlling how the conversation progresses. Harris (1982) examined the topics discussed in conversation and found that interaction usually had a specific purpose and rarely involved partners exchanging anecdotes or passing the time of day. The study by Light, Collier and Fames (1985a) gives extra information about the structure of conversations as it involved sequential analysis of moves made by both caregivers and children. The results suggest that not only did the children in this study produce mainly response turns but that they often forfeited responses that were optional and replied only when obliged to do so. It has also been found that adults tend to take more turns in conversation than children, and to

produce more than one unit (communicative function) within each turn, whilst children produce only one unit per turn (Harris, 1982; Light et al, 1985a).

The picture that emerges of the structure of conversations involving non-speaking children and familiar adults is one of adult domination and control. Such control has also been observed in the functions of communication used by both partners. Adults have been shown to produce a high proportion of questions, commands and requests for clarification, whereas children have produced many yes/no answers and provisions of information (Blackstone & Cassatt in Kraat, 1985; Harris, 1982; Light et al, 1985b; Udwin & Yule, 1991). Provisions of information by children were often requested by the adults (Light et al, 1985b; JollefF et al, 1992), and seldom involved the exchange of new information as the adults' questions were often ones to which they already knew the answer. Adults' requests for information further restricted the children's responses in that they often needed a yes/no answer only. A difference has been observed however, when teachers and parents are compared (JollefFet al, 1992). Parents were found to ask more closed questions than teachers, who in turn asked more real questions that prompted the exchange of new information.

High frequencies of adult questions to children have been observed to be associated with shorter conversational exchanges, and greater use of declaratives and statements by adults to be associated with accelerated language development in early years (Wood, McMahon & Cranstoun, 1980). The conversation style of the partners of physically disabled children does not therefore, auger well for early language development. However, the relationship between adult communication style and language skill acquisition has not been studied

with this group of children and predictions cannot be made regarding the many different areas and stages of language development.

As stated above, caregivers have been shown to seek frequent clarification of the messages produced by non-speaking children. However, children have not always responded to these requests with provisions of clarification. Light, Collier and Fames (1985b) observed that of the turns produced by the caregivers in their study approximately eleven percent involved requests for clarification, whereas only a mean of five percent of children's functions were provisions of clarification. It is possible however, that as in conversations between non-disabled children and their parents, the adults' requests were for confirmation, rather than neutral or specific requests which require repetitions or revisions of the original message, and that the children responded appropriately. As sequential analysis was not employed in this part of the study, we cannot be sure of this proposal. When children did provide clarification in this and other studies (eg. Smith, 1994) they often repeated their original message. Revisions, which often took the form of a new mode of communication being used, for example adding gesture to vocalisation or using their AAC system, were produced when the children were asked to do so. As discussed in relation to preverbal non-disabled children, it may be difficult for some speech impaired children with cerebral palsy to revise their messages in order to provide clarification. Their original vocalisations and gestures may be as clear as they can produce, and they may not have appropriate vocabulary on their AAC systems to express their message. It is also hypothesised that a continuum of abilities of exists for AAC users (eg. Kraat, 1985; Light, 1988). Some users may be more adept at using their systems and may use them spontaneously to clarify, although dififerences between subjects may not be

apparent from group results. Some users who may have more developed linguistic and cognitive skills, may also be able to give alternative messages and persuade listeners to think more laterally to guess their meanings Again this may not be apparent from group studies.

Other functions of communication, such as requests for information and requests for clarification, have been observed to appear very infrequently in the conversation of non­ speaking children (Harris, 1982; Jolleff et al 1992; Light et al, 1985b; McConachie & Ciccognani, 1995; Udwin & Yule, 1991). These functions develop later in non-disabled children (Dale, 1980; Wetherby et al, 1988). As the motor impaired children in the above studies had language and cognitive skills commensurate with or above those of the non­ disabled children studied, the lack of use of these functions cannot be attributable to cognition. Two alternative explanations are possible, however. As discussed in the previous chapter and above, these functions may be easier to produce explicitly using a language based system, and may be more frequently observed in the interaction of more skilled AAC system users, but subject differences may not be distinguishable from group results. Their infrequent use may also be due to the control exerted over the conversation by adult partners which has limited children's opportunities and prevented some children from acquiring the skills (cognition hypothesis). However, as the skills of users have not been analysed in relation to the use of different functions, and sequential analysis has not been employed in the research on communicative functions published to date, these explanations can only remain speculative.

What has been shown, however, is that non-speaking children often use a wider range of communicative fiinctions in elicitation procedures than they do in conversation with their caregivers (Blackstone & Cassatt, in Kraat, 1985; Light et al, 1985b; McConachie & Ciccognani, 1995). In such procedures children are engaged in a semi-scripted conversation with a clinician who presents the children with opportunities to use each target communicative function. The difference between the two situations would not be expected if caregivers also provided opportunities for children to use each of the communicative fiinctions, and if, as proposed by the cognition hypothesis, children learn to produce only the communication skills they have frequent opportunity to use and for which they receive positive reward (adapted from Lamb, 1981; von Tetzchner, 1988). Unfortunately, this hypothesis cannot be tested using current research as the materials used were not piloted to ensure that speaking children and their parents could use a full range of communicative functions. Therefore, the situations in which conversation arose may have limited the interaction observed. Also, different materials have been used to stimulate parents' and children's conversation to those used in the semi-scripted situation, making comparisons and hypotheses about causal relationships difficult.

In the study by Blackstone and Cassatt (1985) all children produced all of the target functions, whereas in the studies by Light, Collier and Fames (1985b) and McConachie and Ciccognani (1995) children produced more, but not necessarily all target functions in the eliciting situation. The difference between the two sets of results may be due to the functions targeted and the eliciting situations. Blackstone and Cassatt (1985) did not attempt to elicit specific requests for information, a function not regularly observed in the other two studies which used similar elicitors.