Eye tracking and avatar-mediated communication in immersive collaborative virtual environments

The research presented in this thesis concerns the use of eye tracking to both enhance and understand avatar-mediated communication (AMC) performed by users of immersive collaborative virtual environment (ICVE) systems. AMC, in which users are embodied by graphical humanoids within a shared virtual environment (VE), is rapidly emerging as a prevalent and popular form of remote interaction. However, compared with video-mediated communication (VMC), which transmits interactants’ actual appearance and behaviour, AMC fails to capture, transmit, and display many channels of nonverbal communication (NVC). This is a significant hindrance to the medium’s ability to support rich interpersonal telecommunication. In particular, oculesics (the communicative properties of the eyes), including gaze, blinking, and pupil dilation, are central nonverbal cues during unmediated social interaction. This research explores the interactive and analytical application of eye tracking to drive the oculesic animation of avatars during real-time communication, and as the primary method of experimental data collection and analysis, respectively. Three distinct but interrelated questions are addressed. First, the thesis considers the degree to which quality of communication may be improved through the use of eye tracking, to increase the nonverbal, oculesic, information transmitted during AMC. Second, the research asks whether users engaged in AMC behave and respond in a socially realistic manner in comparison with VMC. Finally, the degree to which behavioural simulations of oculesics can both enhance the realism of virtual humanoids, and complement tracked behaviour in AMC, is considered. These research questions were investigated over a series of telecommunication experiments investigating scenarios common to computer supported cooperative work (CSCW), and a further series of experiments investigating behavioural modelling for virtual humanoids. The first, exploratory, telecommunication experiment compared AMC with VMC in a three-party conversational scenario. Results indicated that users employ gaze similarly when faced with avatar and video representations of fellow interactants, and demonstrated how interaction is influenced by the technical characteristics and limitations of a medium. The second telecommunication experiment investigated the impact of varying methods of avatar gaze control on quality of communication during object-focused multiparty AMC. The main finding of the experiment was that quality of communication is reduced when avatars demonstrate misleading gaze behaviour. The final telecommunication study investigated truthful and deceptive dyadic interaction in AMC and VMC over two closely-related experiments. Results from the first experiment indicated that users demonstrate similar oculesic behaviour and response in both AMC and VMC, but that psychological arousal is greater following video-based interaction. Results from the second experiment found that the use of eye tracking to drive the oculesic behaviour of avatars during AMC increased the richness of NVC to the extent that more accurate estimation of embodied users’ states of veracity was enabled. Rather than directly investigating AMC, the second series of experiments addressed behavioural modelling of oculesics for virtual humanoids. Results from the these experiments indicated that oculesic characteristics are highly influential to the perceived realism of virtual humanoids, and that behavioural models are able to complement the use of eye tracking in AMC. The research presented in this thesis explores AMC and eye tracking over a range of collaborative and perceptual studies. The overall conclusion is that eye tracking is able to enhance AMC towards a richer medium for interpersonal telecommunication, and that users’ behaviour in AMC is no less socially ‘real’ than that demonstrated in VMC. However, there are distinct differences between the two communication mediums, and the importance of matching the characteristics of a planned communication with those of the medium itself is critical