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Between 1987 and 1991 the University of Maryland's Human-Computer Interaction Laboratory worked on a series of projects which shared a common aspect: the use of touchscreens. The first pole of research was the use of touchscreens for information kiosks.  This was closely tied to our research on Hypertext and Hyperties. As information was becoming easier to navigate with hypertext links, information kiosks were becoming more important for museums and other public places, but mice are unpractical in public settings, so touchscreens are the natural choice!

During 1989-1991, we worked on a home automation system and explored several direct manipulation designs. A playful fingerpainting exploration tool and toy called Playpen was developed. Finally we worked with NCR to explore how touchscreens could be used to replace keyboards when minimum and occasional data entry were needed. We have stopped doing research on touchscreens as successful applications found their ways in museums or cash registers. Pen interfaces, such as in the popular Palm Pilots, have continued the work on touchscreens as they afford a similar sense of "real" direct manipulation.

For a quick summary of our work refer to:

In 1987 (and still long afterwards) touchscreens had the bad reputation of being imprecise. Most user interface books would state that touchscreens selections were "of course limited to targets larger than the average finger".  To use touchscreens for browsing information systems such as Hyperties, we had to be able to select small targets (e.g. the letters of the alphabets of the index table of content). At the time, all touchscreens selections were done in such a way that a target was selected as soon as the finger came over it, and the corresponding action was performed immediately (we called it "first touch" or "land-on" strategy). Errors were common, due to parallax or calibration problems, and users were frustrated when the wrong target was repeatedly selected by mistake.

Lift-Off strategy
A first breakthrough was to propose an alternative technique for selection: the lift-off strategy. As users touch the screen, a cursor is drawn on the screen slightly above the finger. When the cursor is over a target, the target is highlighted. Users can then either lift-off their finger to select the highlighted target, or adjust their position by sliding their finger to a neighboring target. This was a major breakthrough: only the cursor position mattered for the selection, not the finger itself. Selecting a single character was now possible.

88-04  Potter, R.L., Weldon, L.J., Shneiderman, B. (May 1988)
Improving the accuracy of touch screens: an experimental evaluation of three strategies,
Proc. of the Conference on Human Factors in Computing Systems, CHI `88 (Washington, DC) 27-32.
Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 161-169.

89-17 - Sears, A., Shneiderman, B. (June 1989)
High precision touchscreens: design strategies and comparisons with a mouse,
International Journal of Man-Machine Studies, (1991) 34, 4, 593-613.
Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 171-185.

Guide of Volunteered Archaeology (GOVA), for the Smithsonian Museums

The first real test of our strategies for the use of touchscreens was in Spring 1988 when a public access kiosk was designed using Hyperties for the Caesarea (King Herod's Dream) Exhibit, a Smithsonian Museum exhibit on archaeology.  Usability testing in the museum was very important in identifying practical ways to make the touchscreen even more usable.

90-09  Plaisant, C. (Nov. 1990)
Guide to opportunities in volunteer archaeology - case study of the use of a hypertext system in a museum exhibit,
CS-TR-2559, CAR-TR-523
Hypertext/Hypermedia Handbook, Berk E. & Devlin, J., Eds., McGraw-Hill (1991) 498-505.
Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 223-229.
 
89-08 Shneiderman, B., Brethauer, D., Plaisant, C., Potter, R. (May 1989), Evaluating three museum installations of a hypertext, Journal of the American Society for Information Science, 40(3) 172-182.
Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 231-250.

A chapter of Sparks of Innovation tells the story.

Also related to information kiosks:

89-03  Sears, A., Kochavy, Y., Shneiderman, B. (1989)
Touchscreen field specification for public access database queries: let your fingers do the walking,
Proc. of the ACM Computer Science Conference `90 (Feb. 1990) 1-7.
 

In 1987 we started working with a small Maryland Company called American Voice and Robotics. Their focus was on providing home owners with easy control over all major electric systems in the home via a computer equipped with a touchscreen (there was a voice command, but rarely used, except for demos). Our designs included many novel examples of the use of touchscreens (turning hands of watches or sliding flags on timelines).

  90-10  Plaisant, C., Shneiderman, B., Battaglia, J. (1990)
Scheduling home-control devices: a case study of the transition from the research project to a product, Human Factors in Practice, Computer Systems Technical Group, Human Factors Society (Santa Monica, CA, Dec. 1990) 7-13. Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 205-215

89-18  Plaisant, C., Shneiderman, B. (revised Feb. 1991)
Scheduling home control devices: design issues and usability evaluation of four touchscreen interfaces,
CS-TR-2352, CAR-TR-472
International Journal of Man-Machine Studies (1992) 36, 375-393.

Designed originally for home automation, those toggles were later in a NASA design toolkit.

90-08  Plaisant, C., Wallace, D. (Nov. 1990)
Touchscreen toggle switches: push or slide? Design issues and usability study,
CS-TR-2557, CAR-TR-521

This tool was developed by Andy Sears to illustrate the possibilities of touchscreens (and to be a real fun demo!). In particular it demonstrated how touchscreens could do more than selection of targets using location as input, and that speed and direction could also be used for interaction.

Touchscreen keyboards, a series of evaluations Touchscreen keyboards become attractive when only occasional data entry is needed. Several experiments refines our designs. We were able to design a 3 inch wide keyboard and demonstrate 20 wpm for experienced users and 10 wpm for novices.

91-12  Plaisant,C., Sears, A. (Sept. 1991)
Touchscreen interfaces for alphanumeric data entry,
CS-TR-2764, CAR-TR-585
Proc. of the Human Factors Society - 36th Annual Meeting, vol. 1, (Atlanta, GA, Oct. 12-16, 1992) 293-297. Also Sparks of Innovation in Human-Computer Interaction, Shneiderman, B., Ed., Ablex (June 1993) 195-204. Also Human Factors Perspectiv es on Human-Computer Interaction, Selections from Proc. of Human Factors and Ergonomics Society Annual Meetings 1983-1994, Perlman, G., Green, G.K., Wogalter, M.S., Eds. (1995) 261-265.

91-07  Sears, A., Revis, D., Swatski, J., Crittenden, R., Shneiderman, B. (April 1991)
Investigating touchscreen typing: The effect of keyboard size on typing speed,
Behavior & Information Technology, vol. 12, 1 (Jan-Feb 1993) 17-22.

90-06  Sears, A. (revised March 1991)
Improving touchscreen keyboards: design issues and a comparison with other devices,
Interacting with Computers, vol. 3, 3 (1991) 253-269.

• Use a lift-off strategy
• Recess screens at an angle (i.e. elbow resting will solve the arm fatigue problem)

• Making the selectable area larger than the visible target itself (e.g., the button) will really help - it's true for all devices but makes a big difference with the touchscreen.
• You can use speed and direction of the movement too.
• Old touchscreens tend to be unstable and to loose their calibration. You might find it helpful to monitor the drifting of the calibration (i.e. increase in error rates or readjustment of touch position).
• Remember that some gestures unused by mouse applications can be more natural with a touchscreen, e.g., rotating the hands of a watch feels more natural with a touchscreen than a mouse.