Presence and Performance Within VEs

1. Presence and Performance Within VEs By Barfield, Zeltzer, Sheridan and Slater Summarized by Geb Thomas

2. Topics • Definitions • Components of VE • Measuring VE

3. Some Interesting Observations • Attentional resources must be directed to the stimulus information for presence to occur • Although a movie-goer might flinch, they may not feel “present” • Two types of presence: • Observer is actually present one environment • Observer feels present in a different environment

4. Some Definitions • Teleoperator - a machine that operates on its environment and is controlled by a human at a distance • Teleoperator system includes both the operator and the machine -> teleoperator is the remote machine part of the system

5. Types of Teleoperators • Manually controlled • Movements guided by the operator • Master-slave teleoperator • Human positions the slave device, master device follows • Rate controlled teleoperator

6. Robot • From Karel Capek’s Play R.U.R. for Rossum’s Universal Robots • performs functions ordinarily ascribed to human beings, or operates with what appears to be almost human intelligence • Robot Institute of America • reprogrammable multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks.

7. Supervisory Control • Supervising by: • “specifying subgoals, constraints, criteria or procedures to a computer • receiving back a variety of information about a telerobot’s state or performance, often in summary form” • Machine must have some degree of intelligence • Often controlling a complex system in described as supervisory control, even when it is strictly direct control.

8. Telepresence • Human operator receives sufficient information about the teleoperator and the task environment, displayed in a sufficiently natural way, that the operator feels physically present at the remote site • In space teleoperators it may mean equivalent to bare-handed operation.

9. Zeltzer’s AIP Cube • Autonomy • act and react to simulated events and stimuli • 0 for passive, 1 for sophisticated agent • Interaction • Software architecture for the HMI of the VE • 0 for batch processing, 1 for real-time access to all model parameters • Presence • number and fidelity of available sensory channels, task dependant

10. Ellis’ Virtualization • The process by which a human viewer interprets a patterned sensory impression to be an extended object in an environment other than that in which it physically exists • Virtual space -- pictorial depth cues • Virtual image -- accommodation, vergence, stereoscopic display • Virtual Environment -- slaved motion parallax, depth of focus, wide FOV

12. Points on the Cube • 0 0 0 - Models with no autonomy • 1 1 1 - perfect VE • 0 1 0 - commercial animation packages • 0 1 1 - interaction and presence • 0 0 1 - display systems • 1 0 1 - virtual Shakespeare • 1 0 0 - virtual movie? • 1 1 0 - complex autonomous, interactive scenes

13. Determinants of Presence • Extent of sensory information (bits of relevant data) • Control of sensors (navigation) • Ability to modify the environment • Lines of constant information depend unevenly on the different parameters

16. Subjective Measures • A multi-dimensional rating scale, such as NASA-TLX scale

18. Physiological Measures • Things you can measure: heart rate, blood pressure, respiratory rate, electric brain potentials, muscle activity, visual acuity, blink rate, hearing acuity, catecholamines • For VE, we might investigate: • Pupillary responses, amplitude and duration depends on workload • Evoked brain potential, P300 depends on workload.