TNO Human Factors

Virtue: Overview of human factors experiments; concertation meeting 10-11 September 2002

Michael Holewijn (the Netherlands)

Holewijn@tm.tno.nl

2Human Factors

Partners

• BT Exact Technologies: Management• Heinrich-Hertz Institut: Real-time

algorithms• Sony Europe: Hardware systems• Heriot-Watt University: 3-D computer

vision• Technical University Delft: Image processing• TNO Human Factors: Human Factors

3Human Factors

User centered design

Environment

Technical issues

Human Factors

4Human Factors

Background

• 5 user centered

experiments

• Experiments used a mock-

up with the features of the

Virtue system

• Goal: test user specs

described from literature

(D01) & contribute to

requirements final system

5Human Factors

Experiment 1: Effects of shared virtual background

Do subjects perceive a seam in the display?

• task: information sharing• measures: telepresence, information exchange,

cohesion, satisfaction, task performance

• Results: no difference between conditions

6Human Factors

Experiment 2: Value of stereoscopic visualization and motion parallax

• Goals: determine• if stereoscopy and motion parallax are recognizable?• How much freedom of movement is necessary?

• Delft University’s Panorama system

7Human Factors

Results: exp stereoscopic visualization and

motion parallax

• Motion parallax is assessed (48%) more often correctly

than stereoscopy (25%).

• Subjects have to have at least 31 degrees moving

space in order to notice a difference in motion

parallax.

Explanations:• People have experience watching 2D television and are

used to perceive depth based on other cues, such as

interposition.• Panorama system has a limited range of stereo-scopic

and motion parallax effect

8Human Factors

Experiment 3: Effects of delays / synchronization on subjective measures

• Goal: Determine user acceptance of desynchronized

audio-video signals by reducing the audio delay

• Conditions:• video roundtrip delay fixed at 700 ms• audio roundtrip delays: 300, 500 (audio ahead of video), 700

ms

• Measures:, information exchange, cohesion, satisfaction

telepresence, task performance

• `

9Human Factors

Results experiment “Effects of delays / synchronization”

• No effects of audio delays on any performance

measure

• With delays perceived telepresence was significantly

lower

10Human Factors

Experiment 4: Effects of deviations in selective gaze

• Goal: to provide information on the

gaze deviations allowed

• Gaze deviations toward A: 0, 5, 10

degrees• Gaze deviations B<->C: 0, 15, 30

degrees• Measures:

• presence• communication

B C

A

B C

11Human Factors

Results experiment “Effects of deviations in selective gaze”

• Deviations in gaze toward oneself lead to lower spatial

presence than situations without gaze deviations.

• A gaze deviation for the other two participants is often not

visible for the person behind the VIRTUE system. Large

deviations (up to 30 degrees) have no effect on perceived

presence or group communication.

12Human Factors

Design implications

• No seamless background is required to produce a

convincing impression of telepresence.

• Large gaze deviations (up to 30 degrees) have an effect

on perceived presence nor on group communication.

13Human Factors

Design implications

• Stereoscopy and motion parallax features do not have to

be taken into consideration for increasing telepresence.

People are used to using different cues to perceive depth.

• The round-trip delay for audio can be set up to 0.4 s

below that for video (audio may be sent up to 400 ms

ahead of video).

• Different set of tasks and more time pressure may show

beneficial effects of stereoscopy and motion parallax, and

set round-trip delay for audio to 0.3 s below that for video.

14Human Factors

• Goal: to investigate whether and how users adapt

their videoconferencing behavior over time• Conditions:

• 4 types of tasks (brainstorm, negotiation, choice, execute)• Face-to-face (FF) versus Videoconferencing (VC)• 4 times in 2-week intervals

• Measures of performance• task performance• communication structure (e.g., # turns, interruptions, pauses)• communication content (e.g., questions, answers, support)• subjective measures (e.g., presence, cohesion, workload)

Experiment 5: Long-term adaptation

15Human Factors

Conclusions

Performance• VC = FF• Adaptation effect

Structure• FF > VC: more

formal

communication in

VC• No adaptation effect

Content• VC > FF: more positive

expressions in VC• FF > VC: more questions

and fewer answers in VC

VC > FF VC = FF FF > VC

• Performance• Communication structure• Communication content

VC=video conf.FF= face to face

16Human Factors

Assessment of final VIRTUE videoconferencing system

User requirements & acceptance check (September-

October)