Presence and Performance Within VEs

By Barfield, Zeltzer, Sheridan and Slater

Summarized by Geb Thomas

Topics

• Definitions

• Components of VE

• Measuring VE

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

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

Types of Teleoperators

• Manually controlled– Movements guided by the operator

• Master-slave teleoperator– Human positions the slave device, master

device follows

• Rate controlled teleoperator

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.

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.

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.

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

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

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

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

Subjective Measures

• A multi-dimensional rating scale, such as NASA-TLX scale

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.