Recently at the Brighton Science Festival we tried out a new game for younger festival visitors. Previously we’ve had a lot of fun and success with ‘microwave racing’ (see video below) but after covering the carpets of Hove Park Upper School in microwaveable popcorn for the last two years we thought we’d try something slightly different…
…This year we covered their carpets in sticky tape instead.
We created a human medical device! Five people played the game and they took turns to be the number entry interface or the display. Nurses and doctors use real medical devices to get drugs into their patients and we explained how important it is to get the right numbers entered in correctly (more important to be correct than fast, but speed is important too).
We also highlighted that devices (not just medical devices) have many different interfaces (ways of letting the user tell the machine what numbers to show). In the picture below the two infusion pumps have different ways for the user to enter numbers – on the left you press up and down arrows, on the right you press the digits you want to enter, and in both you have to do things in the correct order.
Four of the five game-players made up the numeric DISPLAY – they held a bunch of numbers (zero to nine) which were laminated and hole-punched and stuck into a binder for easy number-flipping at speed. It turns out children are quite energetic!
Here’s a diagram of our DISPLAY showing the numbers 2, 7, 3 and 4 in the four positions. Each of the four people in the display ‘team’ is responsible for one of the positions and they’re told what number to show by the controller. We dispensed with decimal points for the purposes of this game and all the numbers are set to show 0 0 0 0 before the game begins.
The fifth member of the team is the CONTROLLER and they control the number entry interface – we had two different examples to play with, made out of sticky tape (shown below – we did peel it off at the end of the day, no carpets were harmed).
On the left is a simple arrow interface with an UP arrow that tells the display to ‘go up one number’ when pressed once, ‘go up two numbers’ when pressed twice, and so on. The controller then steps or jumps on the RIGHT arrow to move the imaginary cursor position to the second person in the panel, then back to the UP arrow to move that number up to the correct digit, and so on. Once they’ve entered the last number the controller needs to ‘press’ the E for ENTER button at the bottom – so we know they’ve finished.
On the right is a classic number entry interface, similar to those you might find on a mobile phone or calculator – all the numbers are there, so you just need to step on the right one at the right time and then press E for enter at the end.
Playing the game
We kept a huge supply of cards each with a four-digit number on which we’d show to the controller, but keep hidden from the people playing the role of ‘display’. We’d then ask the controller to tell the display, using one of the number entry interfaces only, which four digit number should appear. Then we repeated the experiment by giving them a different number, and asked them to try the other interactive panel – then tell us which they preferred.
Although this was meant to be just a fun version of some of the research that CHI+MED does it nicely illustrates the importance of design in making a device harder or easier to use, as well as the effects design can have on accuracy and the types of errors people make.
Most people found the panel on the right more intuitive, perhaps not surprisingly. Controllers raced through their numbers so quickly that sometimes the “display” struggled to keep up and there were a few errors made. We had to encourage people to think about patient safety and that it was no good getting their numbers entered in under three seconds if they were wrong – imagine if that was your patient!
With the interface on the left the “display” had to watch the feet of the controller very carefully to see how many times they pressed or jumped on the arrow, so they knew what number to select and display. We found that players realised their mistakes as soon as they’d made them and some tried to ‘reset’ things before re-entering (“please can I start again?”). Display players were also very helpful with each other and tried to make sure the right number was showing.
Not surprisingly this interface involved a bit more effort and was much slower to use, but generally quite accurate… as long as everyone was paying attention.
Of course this doesn’t quite reflect the reality of a busy nurse or doctor entering numbers into one or more pumps for unwell patients, but we tried to get some of the older children and their parents to think like a researcher as they played with the ‘devices’.
- What is the best way of entering numbers? What do we mean by best?
- What is the quickest way of entering numbers?
- Which way of entering numbers results in the fewest errors?
- How can we find out the answers to these questions?
You can see how CHI+MED has approached finding answers to these questions in our published research looking at different aspects of number entry systems, below.
Cauchi, A., Curzon, P., Eslambolchilar, P., Gimblett, A., Huang, H., Lee, P., Li, Y., Masci, P., Oladimeji, P., Rukšėnas, R., & Thimbleby, H. (2011). Towards dependable number entry for medical devices. Proceedings of the 1st International Workshop on Engineering Interactive Computing Systems for Medicine and Health Care (EICS4Med), 53–58.
Oladimeji, P., Thimbleby, H. & Cox, A. L. (2013). A performance review of number entry interfaces. Proceedings of 14th IFIP TC13 Conference on Human-Computer Interaction (INTERACT 2013), Part I, 365–382. Lecture Notes in Computer Science, vol. 8117. Springer.
Cauchi, A., Gimblett, A., Thimbleby, H. W., Curzon, P., & Masci, P. (2012). Safer “5-key” number entry user interfaces using Differential Formal Analysis. Proceedings of the 2012 BCS Conference on Human-Computer Interaction (BCS-HCI 2012), 29–38.
Webster, J., Eslambolchilar, P., & Thimbleby, H. (2012). From rotary telephones to universal number entry systems: Can the past re-shape the future? Proceedings of the 2012 Conference on Ubiquitous Computing (UbiComp ’12), 596–597. New York: ACM.
Wiseman, S., Cairns, P., & Cox, A. (2011). A taxonomy of number entry error. Proceedings of the 25th BCS Conference on Human Computer Interaction (HCI-2011), 187–196.
Thimbleby, H., & Cairns, P. (2010). Reducing number entry errors: solving a widespread, serious problem. Journal of the Royal Society Interface, 7, 1429-1439. pdf (647 KB)