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

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.