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The world’s smallest HCI problem

The world’s smallest HCI problem. Paul Cairns. Today’s objectives. Basics of human error Error in HCI Number entry error. Errare humanum est. To err is human # errordiary So it’s not that interesting Change in perception in 1950s. Exercise.

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The world’s smallest HCI problem

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  1. The world’s smallest HCI problem Paul Cairns

  2. Today’s objectives • Basics of human error • Error in HCI • Number entry error Paul Cairns, ADVT Error

  3. Errarehumanumest • To err is human • #errordiary • So it’s not that interesting • Change in perception in 1950s Paul Cairns, ADVT Error

  4. Exercise • Bring to mind an example where something has gone wrong with using a device/system. Whose fault was it? Paul Cairns, ADVT Error

  5. Reason and Rasmussen • Slips • Skill-based • Mistakes • Rule-based, knowledge-based • Violations Paul Cairns, ADVT Error

  6. Exercise: classify • Jumping a red light • Adding milk to a black coffee • Calling someone by the wrong name • Misreading a recipe and adding a tablespoon instead of a teaspoon of chilli Paul Cairns, ADVT Error

  7. Not so simple • What is an error? • Complex, dynamic problems • What causes an error? Paul Cairns, ADVT Error

  8. Studying error • Low error rates • Incomplete cases • Ecological validity • But errors can be systematic Paul Cairns, ADVT Error

  9. Wason Selection Task • Four cards • Each with a letter on one side and a number on the other • Turnover cards to test the rule • If there is a vowel on one side then there is an odd number on the other Paul Cairns, ADVT Error

  10. Wason Selection Task • Four envelopes • Each with a country on one side and perhaps a signature on the other • Turnover cards to test the rule • If it is an international address then it must be signed on the back Paul Cairns, ADVT Error

  11. Explanation • Poor reasoning? • Poor task? • Concreteness? • Really erroneous? Paul Cairns, ADVT Error

  12. Error in HCI • Patterns in people • Devices provoke errors • Task design • Task-action cycle • Post completion errors Paul Cairns, ADVT Error

  13. Paul Cairns, ADVT Error

  14. Medical errors • 10% of all admissions • 10% potentially fatal • 3rd biggest killer in the UK Paul Cairns, ADVT Error

  15. Usual HCI concerns • Task • Context • Workload • Training… Paul Cairns, ADVT Error

  16. Simplify: number entry • Read a number • Transcribe it into a device • Error is any deviation from the written number • Can also measure deviation Paul Cairns, ADVT Error

  17. Which device is better? • Numberpad • Four-key (Chevron) • Five-key • Dial Paul Cairns, ADVT Error

  18. What do errors look like? • Wiseman – 350 errors • No idea! (16%) • Wrong digit (13%) • Anagram (12%) Paul Cairns, ADVT Error

  19. Improving designs • Syntax • System 1 vs System 2 • Visualising quantity Paul Cairns, ADVT Error

  20. Syntax: well-formed numbers • ISMP • Do not use trailing zeros (5 mg, never 5.0 mg). • Use leading zeros for doses less than one measurement unit (0.3 mg, never .3 mg). • Units • Font: 0•35 Paul Cairns, Number entry in medical devices

  21. Regular expressions • Shorthand • Describe “strings” of characters • Three operations: • Sequence • Iteration, * • Optionality, | CS Open Day, Paul Cairns

  22. Examples • Let = “A”|… |“Z” • Num = “0”| … |“9” • LetLetNumNumLetLetLet • “Y” Num* CS Open Day, Paul Cairns

  23. Exercise • Can you come up with a regular expression for ISMP compatible numbers? CS Open Day, Paul Cairns

  24. Checking syntax • Regular expression checker • 10-digit keypad • Model all numbers with error rates • Halve the out-by-10 errors Paul Cairns, Number entry in medical devices

  25. System 1 vs System 2 • Fiction! • Cluster of interesting results • Diemand-Yauman effect • Fortune favours the bold (and the italicized) Paul Cairns, ADVT Error

  26. Effect in number entry? • TypoMadness study • Number entry study • Source or Target? Paul Cairns, ADVT Error

  27. DY Effect works… • … longitudinally? • … acceptably? • … in practice? Paul Cairns, ADVT Error

  28. Summary • Errors are complex • Device design is important • Simple tasks reveal the complexity Paul Cairns, ADVT Error

  29. Reading Diemand-Yauman et al. (2011), Cognition, 118(1) Oladimeji, Thimbleby, Cox (2013), Interact 2013 Reason, Human Error Thimbley, Cairns (2010) J. R. Soc. Interface Wason(1966), Reasoning (or Wikipedia) Wiseman, Cairns, Cox (2011) Proc. of BCS HCI Paul Cairns, ADVT Error

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