Collaboration in Multimodal Virtual Environments Eva-Lotta Sallnäs NADA, Royal Institute of Technology evalotta@nada.kth.se http://www.nada.kth.se/~evalotta/
Research question How is collaboration in a 3D virtual environment affected by if haptic force feedback is provided?
Media richness theory Media differ in richness due to their capacity to carry data that is rich in information like eg. non-verbal cues or tone of voice (Daft, 1998; Rice,1993). In order to cope with an ambiguous situation people process richer information, by for example discussing with other people face-to-face, in order to reach an agreement that gives guidance on how to respond to the situation.
Social Presence Theory The extent that someone feels present with another person in a mediated environment has been addressed in social presence theory (Short et al., 1976). Short et al (1976) regard social presence as a single dimension that represents a cognitive synthesis of several factors such as capacity to transmit information, tone of voice, gestures, facial expression, direction of looking, posture and other non-verbal cues. These factors affect the level of social presence, that is the extent to which a medium is perceived as sociable, warm, sensitive, personal or intimate when it is used to interact with other people. The user is aware of the degree of social presence of a medium, and chooses to use a medium that the user perceives to be appropriate for a given task or purpose.
Presence Presence is defined as the subjective experience of being in one place or environment (mediated), even when one is physically situated in another (Witmer & Singer,1998), the psychological state of being there (Slater & Wilbur, 1997; Hendrix & Barfield, 1996; Held & Durlach,1992; Lombard & Ditton,1997). Control factors: anticipation, mode of control, modifiability. Sensory factors: sensory modality, multimodal presentation, consistency, movement perception, active search. Distraction factors: degree of immersion, selective attention, interface awareness. Realism factors: scene realism, consistent with objective world, meaningfulness of experience, disorientation.
Intermodal relations The sensory modalities are specialised for different tasks, and that specialisation emerges more strongly as the complexity of the task increases (Freides, 1974). Vision is generally dominant over both touch and hearing for the perception of spatial location. Vision is more effective than touch for perception of shape (Heller & Schiff, 1991). Hearing is more effective than vision for the perception of temporally distributed events (Bruno & Penel, 2002). Touch is at least as accurate as vision in the perception of texture. If vision is blurred people rely more on touch for perception of form (Heller & Schiff, 1991).
The sense of touch Tactile perception is defined as perception mediated solely by variations in cutaneous stimulation (Loomis & Lederman, 1986). Kinesthetic perception is defined as perception from joints and muscles, by limb movement alone, of hardness, viscosity and shape. Haptic perception is defined as perception in which both the cutaneous sense and kinesthesis convey significant information about distal objects and events. The haptic system unifies input from many sources, e.g., position of fingers and pressure, into a unitary experience.
Importance of haptic feedback for collaboration Task performance was significantly faster and more precise when haptic force feedback was provided (Ishii et al, 1994; Hurmuzlu et al., 1998; Gupta et al. 1997). A Fitts tapping task was performed significantly faster, by a single user, when haptic force feedback was provided (Arsenault & Ware, 2000). Haptic feedback increased the feeling of togetherness and improved task performance when pairs of people moved a ring on a wire collaboratively (Basdogan et al., 2000). Basdogan et al., 2000 Haptic feedback enhanced the sense of sharing and each user's perception of the actions of the other user when carrying a stretcher together in a virtual chemical plant (Hubbold, 2002).
Haptic collaborative virtual environments Study 1 2 PHANTOMs 2 headsets, telephone connection Between group design 28 subjects Haptic vs. nonhaptic condition Study 2 2 Reachin display systems, stereo vision No verbal communication Within group design 22 subjects Haptic vs. nonhaptic condition
Haptic CVE in study 1 Tasks Five tasks were performed, building constructions with eight cubes.
Haptic CVE in study 2 Task Passing six differently sized cubes between two persons. A collaboratively performed tapping task in order to investigate if Fitts law holds in this situation.
Conclusions from study 1 Supporting haptic force feedback in a distributed collaborative environment makes manipulation of common objects significantly faster & more precise. People perceived their performance to be significantly better in the haptic environment. People perceived themselves to be significantly more virtually present in the haptic environment. But people did not perceived themselves to be more socially present in the haptic environment.
Conclusions from study 2 Error rate was significantly lower when haptic force feedback was provided to people that perform a hand off task in a CVE. Completion time depended on Fitts index of difficulty and increased logarithmically as the size of the hand off object decreased. People perceived their performance to be significantly better in the haptic environment. Haptic force feedback significantly improved perceived virtual presence. Haptic force feedback significantly improved perceived social presence.
Conclusions from study 2 Fitts law proved to hold for a collaboratively performed hand off task in both the haptic and the nonhaptic condition. Effect of cube size: (F 5,50 = 30.2, p < 0.0001) Haptic Completion Time (sec) 3.3 3.2 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 Haptic condition Y = 1.007 +.579 * X; R^2 =.992 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 ID Non-Haptic Completion Time (sec) 3.5 3.4 3.3 3.2 3.1 3 2.9 2.8 2.7 2.6 2.5 Nonhaptic condition Y =.778 +.669 * X; R^2 =.93 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 ID T = 1.01 + 0.579 log 2 (D/W + 1) (r 2 = 0.99) T = 0.778+ 0.669 log 2 (D/W + 1) (r 2 = 0.93)
The subjects own words.study 2 In the environment where you feel, then you feel what the other person does, if both are at the object then you can adjust so that both persons help each other to move in one direction. But in the other environment you have no idea what the other person actually does. Then it can happen that you pull in different directions It felt more insecure...(in the environment without haptic feedback) You signal that you are at (the object) then when you push from the front because you felt that yourself (that you had the object) It was easier to know where you had it.(the cube in the haptic environment)