This demo is adapted from a teaching exercise developed by K. H. Grobman that is available at http:w

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• This demo is adapted from a teaching exercise
  developed by K. H. Grobman that is available at
  http//www.devpsy.org/teaching/method/confirmation
  _bias.html
• Start show with 3rd slide

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(No Transcript)
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• I have a rule in mind that makes sequences of 3
  numbers. In a sequence, order matters. Your goal
  is to figure out the rule in my head! But you
  cant simply ask me. Instead, to determine my
  rule, write a sequence of 3 numbers in the
  sequence column.

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• I will then walk around the room putting either a
  check (meaning the sequence fits my rule) or a
  0(meaning the sequence does NOT fit my rule.
• After I have given you your check (or 0), guess
  my rule. Write the rule out as a sentence or a
  phrase.

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• Then, estimate how sure you are of your guess by
  writing a percent (100 for completely sure and
  0 for completely unsure) in the How sure
  column.

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• To get you started, imagine that your first guess
  was 2, 4, 6. That sequence fits my rule, so I put
  a check on your paper. So, 2, 4, 6 fits my rule.
  Now, you should guess my rule and write down your
  guess as a sentence or phrase in the Guess the
  instructors rule column. Then, estimate how
  sure you are that your guess really is the rule
  in my mind.

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• Now, lets get started on the second row. Guess
  a sequence and wait until I stop by. Once I put
  a check or a zero, you can complete the rest of
  the row and make another guess.
• Once you reach 100 as how sure you are, please
  turn over your paper so I can move quickly past
  you while we wait for everyone else to be as sure
  as you are.

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What was my rule?
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My rule was

• the numbers increase

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Different patterns of guessing

• In the next few slides, Ill present different
  patterns of guessing. While I present these
  patterns, see
• Which of these patterns is most similar to how
  you approached the problem.
• Which pattern is best.

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The danger of playing it safe Not making wrong
guesses doesnt make you right.
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Finding more and more evidence that the earth is
flat makes you more sure that you are rightbut
not more right.
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A Scientific Pattern of Guessing
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Asking Could another rule also fit leads to an
insight
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Asking Could I be wrong? leads to more insights
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(No Transcript)
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We learn as muchif not more from predictions
that were wrong than from ones that were right.
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In science, we are almost never 100 sure.
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Concluding Thoughts I

• Being sure you are right is different from being
  right.
• Smart (high IQ) people are just as likely to
  make the confirmation bias as anyone else, but we
  would expect wise people to make it less.

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Concluding Thoughts II

• Can you think of real life situations in which
  people would be better off asking Am I right or
  wrong? rather than just asking Am I right?
• Some possibilities . (see next slide)

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Need for more scientific testing

• People whose first impressions are always
  right.
• People who believe their horoscopes.
• Prejudiced people.
• People who have strong political beliefs and
  watch a lot of news (but all from the same
  source).
• Youthe last time you were in an argument (and
  you were completely right)?

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Another test Do we know the treatment worked?

• 200 people who got the treatment improved.

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Another test Do we know the treatment worked

• 200 people who got the treatment improved.
• No, for example, we do not know how many who got
  the treatment did not improve.

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Another test Do we know the treatment worked?

• 200 people who got the treatment improved.
• 75 people who got the treatment did not improve.

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Another test Do we know the treatment worked?

• 200 people who got the treatment improved.
• 75 people who got the treatment did not improve.
• No, for example, we dont know how many people
  improved without the treatment.

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Another test Do we know the treatment worked?

• 200 people who got the treatment improved.
• 75 people who got the treatment did not improve.
• 100 people who did not get the treatment
  improved.
• 30 people who did not get the treatment did not
  improve.

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Another test Do we know the treatment worked?

• 200 people who got the treatment improved.
• 75 people who got the treatment did not improve.
• 100 people who did not get the treatment
  improved.
• 30 people who did not get the treatment did not
  improve.
• There is no evidence that the treatment worked.
  Indeed, the percentage of individuals who
  improved is greater is the no treatment group
  than in the treatment group. (If we had doubled
  the number of people in the no-treatment group,
  we could expect 200 of them to improve and only
  60 to not improvethats better than what the
  treatment group did.)
• Adapted from pages 91-92 of
• Stanovich, K.E. (2007). How to think straight
  about psychology
• (8th ed.). New York Allyn and Bacon.

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• Note The previous 6 slides were adapted from
  pages 91-92 of
• Stanovich, K.E. (2007). How to think straight
  about psychology (8th ed.). New York Allyn and
  Bacon.