Human Error and Biases

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Human Error and Biases
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Human Error - Definition

• An inappropriate or undesirable human decision or
  behavior that reduces, or has the potential for
  reducing, effectiveness, safety, or system
  performance.
• An undesirable effect or potential effect on
  systems or people.
• An error that is corrected before it can cause
  damage is an error nonetheless.

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Error ClassificationDiscrete Action

• Omission - Forgetting to do something, or just
  deliberately ignoring it.
• Commission - Performing an act incorrectly.
• Sequence - Right action, wrong order.
• Timing / Rate -Too fast or too slow.

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Error ClassificationInformation Processing

• Specific error categories at each stage of
  information processing.
• 1. Observation of system state
• 2. Choice of hypothesis
• 3. Testing of hypothesis
• 4. Choice of goal
• 5. Choice of procedure
• 6. Execution of procedure

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Error ClassificationInformation Processing -
continued

• The errors depend on the level of behavior.
• 1. Skill-based behavior
• 2. Rule-based behavior
• 3. Knowledge-based behavior

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Error ReductionSelection

• Selection of personnel with skills and
  capabilities (perceptual, intellectual, motor
  skills, etc.)
• Limitations
• 1. Not easy to determine skills required.
• 2. Few reliable tests for measuring skill levels.
• 3. Limited supply of qualified people.

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Error ReductionTraining

• Proper training of personnel reduces errors.
• Limitations
• Old habits are hard to break.
• Training can be expensive.

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Error ReductionDesign

• Exclusion
• Particular errors made impossible to commit
• Prevention
• Particular errors made difficult to commit
• Fail-safe
• Consequences of errors reduced in severity

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Human Biases

• People give an undue amount of weight to
  earlyevidence or information.
• Humans are generally conservative and do
  notextract as much information from sources
  asthey optimally should.
• The subjective odds in favor of one alternative
  orthe other are not assessed to be as extreme
  orgiven as much confidence as optimally they
  should.

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Human Biases - continued

• As more information is gathered, people
  becomemore confident in their decisions,but not
  necessarily more accurate.
• Humans have a tendency to seek far
  moreinformation than they can absorb adequately.
• People often treat all information as if it
  wereequally reliable.

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Human Biases - continued

• People cannot entertain more than a few(three or
  four) hypotheses at a time.
• People tend to focus on only a few
  criticalattributes at a time and consider only
  abouttwo to four possible choices that are
  rankedhighest of those few critical attributes.
• People tend to seek information that confirmsthe
  chosen course of action and to avoidinformation
  or tests whose outcome coulddisconfirm the
  choice. (Confirmation Bias)

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Human Biases - continued

• A potential loss is viewed as having greater
  valuethan a gain of the same amount. (Risk
  Aversion)
• People believe that mildly positive outcomes are
  more likely than either mildly negative or highly
  positive outcomes.
• People tend to believe that highly negative
  outcomes are less likely than mildly negative
  outcomes.