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