UI Design Update Newsletter – August, 2000

Insights from Human Factors International



In This Issue Bob Bailey reviews:

Human Interaction Speeds

What are typical human interaction speeds for reading, listening, speaking, keying, and handwriting?

Human Interaction Speeds
		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.
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).
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).
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).
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).
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."
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 - February 1999. 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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