Although most of the chapters in this book (and in the literature of conversation analysis more generally) report on studies of audiotape recordings of interaction, it does not follow that conversation analysts are therefore uninterested in or content to ignore the possible significance of nonvocal activities. Indeed, the widespread use that has been made of recorded telephone calls as a focus for analysis recognizes a major methodological advantage precisely in the fact that the interactants themselves cannot see each other. The analyst can thus proceed to the study of audio recordings without having to worry about how nonvocal activities may have been involved in any particular sequence. The same obviously cannot be said of interactions where the participants are copresent with one another and, for investigating these, videotapes and films can provide a much fuller record of what occurred. As the relevant technologies become more sophisticated and more readily available, then, research in conversation analysis is likely to pay more attention to issues that can be addressed with reference to an audiovisual data base, and the chapters in this part reflect some of the directions such work is taking.

The range of practical, ethical, and technical problems associated with the use of video recordings for analytic purposes cannot be discussed in detail here (but see, for example, C. Goodwin 1981a).