1. To Err is Human
Owen Brennan

2. January 13th, 2018 – Hawaii, USA

3. 75%-95% of industrial accidents are human error
No official guidance on how to reverse a false alert
38 minutes elapsed before same system sent out a safety broadcast
Wrong option chosen on drop-down menu
Miscommunication, thought it was a real crisis
During day-shift/night-shift switch
Script included line “exercise, exercise, exercise” but also included, “THIS IS NOT A DRILL”
(sorta like saying, “What I am about to say isn’t true don’t listen to me, OH MY GOD RUN THIS IS NOT A DRILL”)

4. Description/similarity slips
Mistakes
Action-Based
Capture Slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based
Memory-Lapse

5. Errors Any deviance from “appropriate” behavior
Norman’s definition
“Appropriate” does not need to be known
General term for all wrong actions
Two sub-categories: slips and mistakes

6. Description/similarity slips
Mistakes
Action-Based
Capture Slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based
Memory-Lapse

7. Slips The action performed was not the action that was intended
Meant to do the “appropriate” thing
Within the seven stages of the action cycle, slips occur in the execution or interpret/perceive stages
Two sub-categories: action based, memory lapse

8. Description/similarity slips
Mistakes
Action-Based
Capture Slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based
Memory-Lapse

9. Action-based slips
Occur in the specify, perform, perceive, or interpret stages of the action cycle
Three subcategories: capture slips, description-similarity slips, mode errors

10. Capture slips
When performing an activity, a similar activity gets performed instead of the desired activity.
The capturing activity is usually one done more recently or more frequently
Examples?

11. Description-similarity slips
Item acted on is similar to, but different from, the target item
Sometimes caused by ambiguous description
Examples?

12. Mode error slips
When there are several modes, or states, that a device could be in, and the user acts upon the wrong mode.
Buttons that can do multiple things
Not enough space for many buttons leads to a need for modes
Signaling what mode the device is currently in would help
Examples?

13. Description/similarity slips
Mistakes
Action-Based
Capture Slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based
Memory-Lapse

14. Memory lapse slips Cause of many more errors
Often caused by interruptions, or too much time between start and finish of desired action
Ways to combat:
Less steps
Reminders
Forcing function
Examples?

15. Description/similarity slips
Mistakes
Action-Based
Capture Slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based
Memory-Lapse

16. Mistakes The wrong goal was established or the wrong plan was formed
From then on it does not matter how well the actions are performed
Three subcategories: rule-based, knowledge-based, memory-lapse

17. Rule based mistakes
Mistake involving rules, dealing with familiar/prepared situations
Multiple ways in which this can occur
The situation is misinterpreted so the wrong rule is invoked
The rule itself is faulty
Correct rule is invoked, but the outcome is incorrectly evaluated
Examples?

18. Knowledge based mistakes
Occurs in novel situations, so there are no rules to invoke
New procedures must be devised
Helped by good conceptual models, manuals, or AI help.
Examples?

19. Memory-Lapse Mistakes
Similar to before, but these memory-lapses cause the goals and plans to be wrong
Helped by making all the relevant information available to the user
Examples?

20. Description/similarity slips
Mistakes
Action-based
Capture slips
Description/similarity slips
Mode errors
Memory-lapse
Errors
Rule-based
Knowledge-based

21. Handling Errors 5 Why? Method: asking why a bunch to get to the root
Poka-Yoke method: physical obstructions/indicators to prevent errors
Encourage reporting errors, punish not reporting errors
Discovering errors quickly limits their damage
Feedback helps with slips
Mistakes are harder to detect

22. Designing for error Constraints block potential errors
Make it easy for users to undo errors
Make it easy for users to know if they have made an error
Confirmation/error message
Make it easy to resume after an interruption
Prevent possible interruptions
Provide well-designed warning signals (usually not the answer though)

23. Minimizing slips
Make sure controls are distinct, both in appearance and position
Eliminate most/all modes if possible
If not, display all the modes with the current mode distinct from the rest
Reminders for infrequent tasks
Initial steps should be dissimilar
Training

24. Design principles
Lessen the amount of knowledge that has to be in the head, keep it in the world
Use natural and artificial restraints to exploit how users interact with a device
Provide feedforward (what options are available) and feedback (make the results apparent)

25. Navigation Bloopers
Let the user know where they are, where they can go, and where they have been

26. Some blooper examples Window does not have a title
Window title appears on multiple different pages
Window title does not match where it was linked from
Distracting buttons/links
No way to backtrack
Self-links
Too many dialogue boxes
Multiple search boxes
Poor search result browsing/noisy search results

29. Back to Hawaii… What type(s) of errors occurred?
How could the errors have been prevented?
How could the errors have been better handled?

30. Bib
hawaii
Don Norman, The Design of Everyday Things, Chapter 5
Jeff Johnson, GUI Bloopers 2.0, Chapter 3