Virtual Reality Lecture 4. Human Factors : Psychological and Cognitive Issues 고려대학교 그래픽스 연구실

Basic model of perception & cognition H-sensor perception cognition motion control H-effector action Human Natural environment sensing knowledge

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

Presence and Reality 1. Tele-presence and Virtual presence 2. AIP cube 3. Model P 4. Measuring reality 5. Philosophical considerations

1. Tele-presence INDEPENDENT VARIABLESDEPENDENT MEASURES Experimental determination of presence,learning efficiency, and 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 simulated 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 Digital Shakespeare Task Level Graphical Simulation Conventional Animation Systems ca "Virtual Reality" (1,1,1)

Interesting possibilities 000batch processing of simple models on plotter 001  non-interactive virtual tour 010  animation systems 011  commercial virtual environment 100high precision simulation 101"Virtual Theater" 110MUD(?) 111truly a Virtual Reality Autonomy Interaction Presence 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