OVERCONFIDENCE

1
OVERCONFIDENCE

• Plous Ch 19

2
Pervasive - Public policy

• Odds of meltdown 1 in 10,000 years
• Ukraine Minister of Power, 2 months before
  Chernobyl
• accident

• NASAs official launch risk estimate before
  Challenger disaster
• 1 catastrophic failure in 100,000 launches
• (daily shuttle launch for 3000 centuries
• before accident!)

3
Joseph Kidd - in 4 parts

• People (Psychologists, grad students and
  undergraduates) ALL
• INCREASED their CONFIDENCE but not their ACCURACY
  with
• INCREASED AMOUNTS of INFORMATION (Oskamp, 1965)

4
General finding replicated

• Overconfidence greatest when accuracy near chance
  levels
• Overconfidence DIMINISHES as ACCURACY INCREASE
  from 50-80
• (often UNDERCONFIDENT when accuracy over 80)!
• Gap NOT related to DMs intelligence

5
Implications

• Basis and maintains
• COGNITIVECONCEIT

• unwarranted faith in ones intuitive reasoning,
  judgements, and dm
• abilities

6
Regular Feedback information

• DECREASES OVERCONFIDENCE
• I.e. Weather Forecasters

7
Most people highly overconfident

• Calibration research
• How confident are you
• see Plous p. 224

• finding
• only 1 got 9/10 correct
• most missed 4-7
• (Russo Schoemaker (1989)

8
Political Implications

• Sentencing guidelines
• find defendant guilty only if you are
• sure BEYOND a SHADOW of a DOUBT
• ..gt
• Innocents EXECUTED capital cases

9
Cognitive limitations or Bureaucratic cultural
norms?

• Overconfidence
• or
• Need to appear confident?
• Diane Vaughn Space-shuttle launch
  disaster.gtNORMALIZATION of
• DEVIANCE

10
How to reduce Overconfidence

• Practice with intensive feedback information (N
  200 judgments)
• STOP! Why might your judgment be
• WRONG?