Lecture: Human Errors

Classified into

Slips

Mistakes

Right action is formulated but wrong execution

If system itself not well designed and the right goal is not well formulated

Corrected by better screen design

User does not understand system so more radical changes in design or improved training

Preventing Errors

Perceptual Errors (Read-Scan)

Cognitive Errors (Think)

Motor Errors (Respond)

  • Display of objects that are fairly similar
  • Lack of perceivable feedback
  • Failure to capture user's attention
  • Taxing user's memory
  • Lack of poor mnemonic aids
  • Inconsistency
  • Pressure for speed
  • Requires high degree of eye-hand coordination

Types of Slips

Capture Error: Continue frequently done activity instead of intended one

Description Error: Intended action has much in common with others

Data driven Error: Triggered by arrival of sensory info which intrudes with normal action

Associative activation: Internal thoughts and associations triggers action

Loss of Activation: Forgetting main goal in the middle of sequence of actions

Mode Errors: Doing action in one mode thinking that you are in another

Prevention Guidelines

  • Eliminate Modes or provide cues for modes
  • Maximize recognition, minimize recall
  • Allow reconsideration of action by user
  • Minimize need for typing

Recovery Guidelines

  • Provide appropriate type of response
  • Ask user what should've been done then allow error action as legal one
  • Provide undo function
  • Provide cancel function from operations in progress
  • Require confirmation for drastic actions
  • Provide reasonableness checks on input data