USER INTERFACE DESIGN UPDATE - August, 2000

Insights from Human Factors International, Inc. (HFI)
Providing consulting and training in software ergonomics.
(http://www.humanfactors.com/home/)

Every month HFI reviews the most useful developments in
UI research from major conferences and publications.
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In this issue Dr. Bob Bailey reviews:

What are typical human interaction speeds for reading, listening,
speaking, keying, and handwriting?
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As designers make decisions among different input and output
technologies, frequently they must consider the speed with which
users typically perform. Many maximum human interaction speeds
are summarized in my book, Human Performance Engineering
(Bailey, 1996, p. 42).

Over the past couple of years, many studies were reported that
have added to our understanding of how fast people process
information in real world situations. These can be considered as
“typical speeds.” This information can be very useful, but is difficult
to find, and so I have summarized some of it here.
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1. Reading

The average adult reading speed for English prose text in the United
States seems to be around 250 to 300 words per minute.

This reading speed can be substantially increased when using rapid
serial visual presentation (RSVP). People with little practice can
read at 400 words per minute, while those with even less than
one hour of practice can easily read at speeds of 600 to 800 words
per minute or faster (Bailey and Bailey, 1999).

When people are proofreading (scanning) text on paper they do so
at about 200 words per minute. Performing the exact same task
using a monitor, they proofread about 10% slower at 180 words
per minute (Ziefle, 1998).
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2. Listening

People comfortably can hear words that are spoken at from 150 to
160 words per minute. This is generally the recommended rate for
those who are preparing “books on tape,” or for narration in videos
(Williams, 1998).

However, when normal speech is increased to 210 words per
minute, using compression, there is no loss in comprehension
(Omoigui, N., He, L., Gupta A., Grudin, J. and Sanocki, E., 1999).
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3. Speaking

People tend to dictate to computers at about 105 words per minute
(Karat, Halverson, Horn, and Karat, 1999; Lewis, 1999). Even
so, there will be some mis-recognitions by the speech recognizer.
After making the required corrections, the speaking rate was reduced
to an average of 25 words per minute when doing transcription.
New users had an average speaking rate of 14 words per minute
when transcribing, and only 8 words per minute when composing
(Karat, Halverson, Horn, and Karat, 1999).
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4. Keying

The fastest typists can enter well over 150 words per minute. Many
jobs require keyboard speeds of 60-70 words per minute. However,
when actual typing speeds are collected for people that use computers,
they are much slower. In one study the typing rates for simple
transcription averaged only 33 words per minute, and for composition
the average was only 19 words per minute (Karat, Halverson, Horn,
and Karat, 1999).

In this same study, participants were divided into three groups
according to their typing skills.  The fastest typists averaged only 40
words per minute, those that had “moderate” speed averaged 35
words per minute, and those that were considered “slow” typed at
23 words per minute.

Two-finger typists can key memorized text at about 37 words per
minute, and copy from one form to another at about 27 words per
minute (Brown, 1988).
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5. Handwriting

On average, people write (handprint) at about 31 words per minute
for memorized text, and about 22 words per minute when copying
text (Brown, 1988). It is interesting that the original Remington
typewriter was sold with the promise that it would enable users to
enter information “twice as fast as they could write.”
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References

Bailey, R.W. (1996). Human Performance Engineering: Designing
High Quality Professional User Interfaces for Computer Products,
Applications and Systems, Prentice-Hall: Upper Saddle River, NJ.

Bailey, R.W. and Bailey, L.M. (1999), Reading speeds using
RSVP, User Interface Update – 1999.
http://www.humanfactors.com/library/feb99.asp

Karat, C.M., Halverson, C., Horn, D. and Karat, J. (1999),
Patterns of entry and correction in large vocabulary continuous
speech recognition systems, CHI 99 Conference Proceedings,
568-575.

Lewis, J.R. (1999), Effect of error correction strategy on speech
dictation throughput, Proceedings of the Human Factors and
Ergonomics Society - 1999, 457-461.

Omoigui, N., He, L., Gupta A., Grudin, J. and Sanocki, E. (1999),
Time-compression: Systems concerns, usage, and benefits,
CHI 99 Conference Proceedings, 136-143.

Williams, J. R. (1998). Guidelines for the use of multimedia in
instruction, Proceedings of the Human Factors and Ergonomics
Society 42nd Annual Meeting, 1447-1451.

Ziefle, M. (1998), Effects of display resolution on visual
performance, Human Factors, 40(4), 555-568.
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3-day 1999 Annual User Interface Update Seminar presented by
Dr. Robert Bailey.
http://www.humanfactors.com/training/annualupdate.asp.
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REGISTER for UI Update Seminar:

Chicago, IL - September 11-13, 2000
https://www.humanfactors.com/training/registration/AUregister7.asp

San Francisco, CA - October 11-13, 2000
https://www.humanfactors.com/training/registration/AUregister8.asp
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Suggestions, comments, questions?
HFI editors at mailto:hfi@humanfactors.com.

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