Virtual Reality

Lecture 4. Human Factors : Psychological and Cognitive Issues

고려대학교 그래픽스 연구실

Contents

• Presence and Reality• Human Visual System• Human Auditory System• Other Perceptual systems• Cognitive system

Presence and Reality

1. Tele-presence and Virtual presence2. AIP cube3. Model P4. Measuring reality5. Philosophical considerations

1. Tele-presence

INDEPENDENT VARIABLES DEPENDENT MEASURES

Experimental determination of presence,learning efficiency, and performance.

extent of

sensory

information

control of

sensors

PRINCIPAL

DETERMINANTS

OF PRESENCEability to

modify

environment

task difficultyMAJOR

TASK

VARIABLES

degree of

automation

sense of presence subjective rating objective measures

training efficiency

task performance

2. AIP Cube

• Zeltzer (1992)

• A model for describing, categorizing, comparing various VEs, rather than what contitutes the sense of presence.

• Three components– autonomy– interaction– presence

autonomy and Interaction

• Autonomy– the ability of a computation model to act and react to simulat

ed events and stimuli• 0 : passive, geometric model• 1 : most sophisticated, knowledge based virtual agent• 0.x : physics-based model

• Interaction– the degree of access to model parameters at runtime

• 0 : "batch" processing - no interaction at runtime• 1 : comprehensive, realtime access to all parameters

autonomy vs. interaction

• autonomy - interaction plane– Two axes are complementary (or inter-

related).– The level of interaction is (inversely)

determined by the degree of autonomy.

• degree of freedom problem– Providing direct assess to many parameters

is not necessarily productive.

presence

– A rough, lumped measure of the number and fidelity of available sensory input and output channels

– Measure of the Selective Fidelity

– must consider the degree of match between the sensory data and mental model.

– may consider sensory substitution (e.g., auditory output, instead of haptic).

autonomy, interaction, presence

(0,0,0)

(1,0,0) (1,1,0)

(0,1,0)

(0,1,1)(0,0,1)

(1,0,1)

Autonomy

Interaction

Presence

DigitalShakespeare

Task LevelGraphical Simulation

ConventionalAnimationSystemsca. 1990

"Virtual Reality"

(1,1,1)

Interesting possibilities

0 0 0 batch processing of simple models on plotter0 0 1 non-interactive virtual tour0 1 0 animation systems0 1 1 commercial virtual environment1 0 0 high precision simulation 1 0 1 "Virtual Theater"1 1 0 MUD(?)1 1 1 truly a Virtual Reality

Autonomy

InteractionPresence Typical System

3. Model P

• Perception– visual– auditory– tactlie– etc.

• Interaction– self– environmental– social

• Model– geometry– kinematics– dynamics– behavioral– cognitive– emotional

• Factors that affect the quality of perception– inclusiveness– surroundedness– extensiveness– vividness– synchronization

4. Measuring reality

(1) Psychological and subjective measures(2) Psychophysical measures(3) Physiological measures(4) Performance measures(5) Reflex response

(1) Psychological and subjective measures• procedure

i) Scale rating along a uni-directional axis.ii) Compute the psychological distance

• Ex. NASA TLX scale– mental load = f (mental demand, physical demand,

temporal demand, performance, effort)• Ex. Presence assessment

• Ex. factorial studies

• Ex. Discrimination between a real and a virtual worlds

P (judged “real” | actually real)P (judged “real” | actually virtual)

idea: image quality virtual < real virtual = real + noise

(2) Psycho-physical measures

• measures more “local” parameters.

• Types of classic problems– sensory threshold– recognition– discrimination– scale

(3) Physiological measures

• classes– cardiovascular– respiratory– nervous– sensors– blood chemistry

(4) Performance measures

• Examples– # of errors– time spent– accuracy

• Assumption: presence = f (performance)

• But, we may decrease presence intentionally in order to increase performance.

(5) Reflex response

• Response to unexpected / threatening stimuli.

• Socially-conditioned response

• effects of prolonged exposure

5. Philosophical considerations

• Theories on reality– Plato– Leibniz– Goodman– Popper