The effect of modality on social presence, presence and performance in collaborative virtual environments
Humans rely on all their senses when interacting with othersin order to communicate and collaborate efficiently. Inmediated interaction the communication channel is more or lessconstrained, and humans have to cope with the fact that theycannot get all the information that they get in face-to-faceinteraction. The particular concern in this thesis is howhumans are affected by different multimodal interfaces whenthey are collaborating with another person in a shared virtualenvironment. One aspect considered is how different modalitiesaffect social presence, i.e. people's ability to perceive theother person's intentions and emotions. Another aspectinvestigated is how different modalities affect people´snotion of being present in a virtual environment that feelsrealistic and meaningful. Finally, this thesis attempts tounderstand how human behaviour and efficiency in taskperformance are affected when using different modalities forcollaboration.In the experiment presented in articles A and B, a sharedvirtual environment that provided touch feedback was used,making it possible to feel the shape, weight and softness ofobjects as well as collisions between objects and forcesproduced by another person. The effects of touch feedback onpeople's task performance, perceived social presence, perceivedpresence and perceived task performance were investigated intasks where peoplemanipulated objects together. Voicecommunication was possible during the collaboration. Touchfeedback improved task performance significantly, making itboth faster and more precise. People reported significantlyhigher levels of presence and perceived performance, but nodifference was found in the perceived social presence betweenthe visual only condition and the condition with touchfeedback.In article C an experiment is presented, where peopleperformed a decision making task in a collaborative virtualenvironment (CVE) using avatar representations. Theycommunicated either by text-chat, a telephone connection or avideo conference system when collaborating in the CVE. Bothperceived social presence and perceived presence weresignificantly lower in the CVE text-chat condition than in theCVE telephone and CVE video conference conditions. The numberof words and the tempo in the dialogue as well as the taskcompletion time differed significantly for persons thatcollaborated using CVE text-chat compared to those that used atelephone or a video conference in the CVE. The tempo in thedialogue was also found to be significantly higher when peoplecommunicated using a telephone compared to a video conferencesystem in CVEs. In a follow-up experiment people performed thesame task using a website instead, with no avatar but with thesame information content as before. Subjects communicatedeither by telephone or a video conference system. Results fromthe follow-up experiment showed that people that used atelephone completed tasks significantly faster than those thatused a video conference system, and that the tempo in thedialogue was significantly higher in the web environments thanin the CVEs.Handing over objects is a common event during collaborationin face-toface interaction. In the experiment presented inarticle D and E, the effects of providing touchfeedback wasinvestigated in a shared virtual environment in which subjectspassed a series of cubic objects to each other and tapped themat target areas. Subjects could not communicate verbally duringthe experiment. The framework of Fitts' law was applied and itwas hypothesized that object hand off constituted acollaboratively performed Fitts' law task, with target distanceto target size ratio as a fundamental performance determinant.Results showed that task completion time indeed linearlyincreased with Fitts' index of difficulty, both with andwithout touch feedback. The error rate was significantly lowerin the condition with touch feedback than in the condition withonly visual feedback. It was also found that touch feedbacksignificantly increased people's perceived presence, socialpresence and perceived performance in the virtual environment.The results presented in article A and E analysed together,suggest that when voice communication is provided the effect oftouch feedback on social presence might be overshadowed.However, when verbal communication is not possible, touchproves to be important for social presence.
School:Kungliga Tekniska högskolan
Source Type:Doctoral Dissertation
Keywords:collaborative virtual environments; modalities; media richness; social presence; presence; communication media; haptic force feedback
Date of Publication:01/01/2004