Transcript Cognitive Biases

Cognitive Biases
Yan Bulgak
Mar 550 December 04
What Are They
• A Cognitive Bias is the result of observation by
a given person or persons that creates a
skewed perception of “reality”
Confirmation Bias
• Tendency to accept evidence confirming a
held opinion while rejecting contradicting
evidence
– Underlies the fallacy of seeking scientific proof
while not seeking disproval of alternative
hypotheses
– “You see what you expect to see”
• The Murano™ Drivers
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Selection Bias
• Non-random selection of samples for
experiment, thereby biasing the results
– Rejection of “bad” data
– Early trial termination
– Medical trails – excluded data for patients who
died or left.
• See above Murano Drivers example
• Evans proposed the ``Positivity Bias’’ – people
confirm because they can’t think of how to
falsify
Need For Closure…
• …and the 2 am drunken phone call to the
girl/boy friend you’ve not seen in 3 years.
• People tend to avoid ambiguity on certain
matters
Hyperbolic Discounting
• Tendency to perceive immediate lesser gain as
being more attractive than longer-term
greater gain (even if greater gain is actually
better for them)
Outcome Bias
• …or the “I told you so” effect
• Judging of past decisions on outcomes,
though at decision time outcomes were
uncertain
– “Good researcher” is one who selected a topic
that “worked”
Planning Fallacy
• …or Cheops’s Law “Nothing is ever built on
time or within budget”
• Tendency to underestimate completion times
Self-Fulfilling Prophecy
• Situation which initially false, becomes true
through actions on the part of the actor.
– Expectations of failure leads to failure
Notational Bias
• A bias toward a particular range of expression
that is circumscribed by the notation available
– Western music: based on 12 tone equal
temperament (TET) – ratio of
– Ancient Chinese music used 7 (TET)
– Arabic music uses 24 TET
Notational Bias (cont)
• In Computer Science, a language that offers
easy access to certain structures can define a
pre-disposition toward a particular solution
method that will carry over even into other
languages
– Examples:
• PERL
• Lisp and functional languages
Causes of Cognitive Bias
• Attribution
• Cognitive Dissonance
• Heuristics (recall Troy’s presentation)
– Representativeness
– Availability
– Anchoring
Attribution
• Relies on Internal/External distinction in
attributing blame/responsibility
• Positivity Effect
– Observer will attribute positive actions of a person
they dislike to External factors, and negative
actions to their internal disposition
– Inverse for Negativity Effect
• In general, people underestimate External
effects
Attribution (Cont)
• Other examples:
– “Everything is easy to the man who doesn’t have
to do it himself”
– Backseat drivers
– The “I told you so” effect
Cognitive Dissonance
• Simultaneous expression of two contradictory
beliefs
– E.g. “I believe in the US Constitution” and “I am
against free speech”
• Holding such beliefs creates tension, which is
reduced by changing the attitude toward one
of the beliefs – the one that is least resistant
to change.
Examples
• George Orwell’s 1984 and “Doublethink”
– MiniPax, MiniLuv, MiniTruth and MiniPlenty
• Post-Purchase Rationalization
Effort Justification
• Experimental evidence shows that subjects
will rate initially undesirable objects higher if
forced to suffer adversity to attain them.
– Dissonance between:
– Avoiding unpleasant effort
– Mediocre outcome
– Takes least effort to adjust evaluation of outcome.
• Job Interviews
• Military Bootcamp
Logical Fallacies
• Post-hoc ergo propter hoc
– Mean global temperatures are higher today than in 1800.
The number of pirates today is smaller than in 1800.
Therefore pirates and global temperatures are inversely
correlated
• Gambling expectation
– Next ball will surely be red…
• Murphy’s Law
The Texas “Sharpshooter”
• Sharpshooter Story
• Logical fallacy of adjusting hypothesis to
outcome
– Disconfirmation as strengthening cultist belief
• Shakespearean Sonnets
• and…
The Torah/Bible Code
• Creates a space of letters by choosing every
nth letter of the text
• Look for “patterns”
• Claim of future prophecies in the Pentateuch
of the Torah
– Rabin Assassination
– 32 Famous Rabbis Experiment
‫”‪The Famous “Prophesy‬‬
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‫‪Assassin‬‬
‫‪Yitzhak Rabin‬‬
Example
• LoremipsumdolorsitametconsectetueradipiscingelitPhasellusunelitSedligul
alacusportaveldignissimeususcipitsedfelisPhasellusetnibhutaugueconsequ
atvehiculaCrasfelissapiensemperafacilisissollicitudincondimentumeuismod
orciNamauctorlobortiselitCraseliterosrhoncusacauctorvit
• N=5
• LoremipsumdolorsitametconsectetueradipiscingelitPhasellusunelitSedligul
alacusportaveldig
• LidsestdclauldlutdsuieissbuouhafsneciluoeeoiultisehsciasaainifietsenauvI
minuutn
Concerns and Refutations
• On the non-statistical side:
– Clear example of Confirmation and Selection bias
• Statistical side:
– McKay et al showed that Rabbi experiment highly sensitive to minor
changes
– Liberties and choice of Rabbi names
– Other linguistic features, when altered, reduce statistical likelihoods by
many orders of magnitude
– Replicated experiment with War And Piece can be made to yield
significance results of 1 in a million!
完
Bibliography
• Brock, T. C. and M.C. Green (Eds). Persuasion: Psychological Insights And
Perspectives 2nd Ed. Thousand Oakes, CA: SAGE Publications, 2005
• Drosnin, M. The Bible Code. New York, NY: Simon & Shuster, 1997
• Evans, Jonathan St. B.T. (Ed). Bias In Human Reasoning: Causes And
Consequences. Hove, UK: Lawrence Erlbaum Assoc, 1989
• Kahneman, D., Slovic, P. and A. Tversky (Eds). Judgment under
Uncertainty: Heuristics and Biases. Cambridge, UK: Cambridge University
Press, 1982.
• McKay B., Bar-Natan D., Bar-Hillel M., and G. Kalai. Solving The Bible Code
Puzzle. Statistical Science Vol.14 150-170, 1999
• http://en.wikipedia.org/wiki/List_of_cognitive_biases
• Witztum D, Rips E. and Y. Rosenberg . Equidistant Letter Sequences in the
Book of Genesis. Statistical Science Vol.9 429-438, 1994