The topic of this thesis is the notion of dialogue and how machines have not only influenced
the development of our understanding of this fundamental human social activity but also the
possibilities for engaging in mediated dialogue. In particular, the concern is with its adoption
and distortion from a computational point of view. An interactional perspective is developed
that provides insight into the problems and limitations of computer dialogue models, motivates
the investigation of the achievement of dialogue mediated 'through' machines, and informs
the conception and design of computer systems (or artifacts) that support the metaphor of
dialogue 'with' machines.
To motivate a reconstruction of the notion of dialogue and a different understanding of the
status of machines in terms of action, a critical analysis of computer models of dialogue,
concerning theory, data and implementation, is given. In general, computer models lack a
consideration of interaction as a constitutive domain, assume the interchange model of
dialogue, promote a sanitised view of data, and are a poor foundation for the design of
machines that are to engage in dialogue-like behaviour with a user. An alternative
interactional perspective is derived from hermeneutics and ethnomethodology in which it is
argued that the machine is an intelligible - not intelligent - artifact, and communicative activity
is circumstantial, situated and interactively constituted. Instead of reifying dialogue as the
repeated exchange of discrete messages between isolated cognitive processors (the
interchange model), dialogue is understood here to be the collection of practices in which
parties are mutually engaged in coordinating communicative actions and achieving shared
understanding out of the materials at hand. The empirical methodology of the thesis comes
from conversation analysis and forms the basis for the investigation of the achievement of
dialogue 'through' machines.
A detailed audio-visual study of a particular computer-mediated communication modality is
presented. Parties engaged in cooperatively constructing mutual orientation in dialogue (in
a virtual dialogue space) were recorded and features of their conduct were rendered for
analysis with the aid of a notation system specially developed for this study. The findings
are that the computer-mediated dialogue activity is a skilled, interactive accomplishment in
which dialogic presence, monitoring and participation are contingently created and
maintained. An emergent transformation of the dialogue activity demonstrates the situated
work of constructing participation, a process that is shaped by the dynamics of that activity.
A brief study of copresent collaboration documents two further features: the embodiment of
actions and their complementarity. The consequences of the interactional perspective and
the empirical study for computer models and dialogue 'with' machines are discussed.
Suggestions are also made about an alternative use of computer modelling for dialogue
'between' machines, and about the future of dialogue mediation and artifacts
