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The Beneficial and Harmful Effect ofVideoconferencing
Milton Chen, PhD
Human Computer Interaction Lab
Stanford University
Presented at the 21st NORDUnet Network Conference 8/25/2003
AccomplishmentsIntel President Paul Otellini demonstrated vsee
during his keynote at IDF
Candidate system for International Space Station• With Bob Bradford, MSFC
Featured Internet2 project to break video wall record• Attempt to see all 200 members of Internet2 simultaneously
Videoconferencing Solutions
Max video links
Max video resolution
Bandwidth at 352x288 15fps
Microsoft NetMeeting,
Yahoo Super Webcam
1 352x288 ~200 Kbps
Polycom, Tandberg, … 4 352x288 ~200 Kbps
vsee ~16 720x480* ~100 Kbps
* At 30 fps on a 3 GHz Pentium 4
first mobile phone, 1924 first handheld phone, 1973
1st Revolution: Possible 2nd Revolution: Ubiquitous
first videophone, 1927
An anatomical explanation
looking at you looking sideways
looking up
looking down eye closing
Illustrations from The Artist’s Guide to Facial Expression[Faigin ’90]
Tyranny of real classroomsvsee
A new hat3:29 am
“We shape our tools, and there after our tools shape us”
- Marshal McLuhan
Why read lips
Improves comprehension – Background noise [Sumby and Pollack ’54]– Hearing loss [Binnie, Montgomery, Jackson ’86]
[Yarbus ’67]
Audio ahead of the video
Videoconferencing– 1 msec to encode 30-msec audio with TrueSpeech– Up to 250 msec to encode a 720x480 frame with
high-quality MPEG-4
Detectable skew130 msec [Dixon and Spitz ’80]
80 msec [Steinmetz ’96]
Conventional lip synchronization
encodenetworkdecode
A
a v
time
Unsynchronized
encodenetworkdecodesync
a, v
Audio delay lineA
delayskew
Attribute delay and skew to remote person
=> person is slow?
=> person is not believable?
[Reeves and Nass ’96]
encodenetworkdecode
A
a v
time
Unsynchronized
encodenetworkdecodesync
a, v
Audio delay lineA
delayskew
Perception of variable AV skew
* 16 subjects judged recorded videos of 1 speaker
0
25
50
75
100
200,unsync 200,slow 200, fast sync
initial skew (msec) , stretch period
lip s
ynch
roni
zatio
n (%
)
Tyranny of real classroomsvsee
A new hat3:29 am
To see or not to see
“The heart is stirred more slowly by the ear than by the eye.”
– Horace
Benefit of video medium
Facilitate communication process– Stimulate interactivity when group is medium size
– Support tasks that require complex collaboration• Negative feedback
• Negotiation
Build relationship– Establish identity
– Build trust
– Form friendship
Harmful effect of video
Time and resource sink
Make user look bad– Gaze less potent => are you ignoring me?
– Gesture less potent => am I not interesting?
– Slow response => user is slow?
– Lack of lip sync => user is not believable?
– Lack of eye contact => user is not motivated? [Reeves and Nass ’96]
A plane that does not fly is not a plane
First flight, Wrights 1903
A videophone that limits communication is not a videophone
What is a videophone