How “Systems” Can Help with Error Prevention? (Reason, 1990)

• “Forcing Functions”
• “Something that prevents the behavior from continuing until the problem has been corrected”
• Example:
  • Audi accidents of 1980’s – cars uncontrollably lurching forward or backwards when shifting out of “park”
  • You now must depress foot brake to shift from “park” to “drive” or “reverse”
• System responses to error
  • “Gagging” - prevents user from “expressing unrealizable intentions” (e.g., automatic shutoff of machine in response to dangerous input))
  • Warnings
  • “Do nothing” (not respond to illegal input)
  • Self-correct
  • “Let’s talk about it”
  • “Teach me”