1. How we know what isn’t so – cognitive factors in false beliefs
Dr. Jeff Saunders
Dept of Psychology
Hong Kong University

2. False beliefs Topic: cognitive factors in false beliefs
How we acquire false beliefs?
What cognitive tendencies lead us acquire mistaken beliefs about the world?
Why do false beliefs persist?
What tendencies inhibit us from learning from experience and correcting false beliefs

3. Demo: try to outwit the professor in a card guessing game

4. Card game strategy? ‘Strategy’: choices were entirely random!
But might have perceived that that there was some causal strategy behind choices
No way that opponent could have done better or worse than chance
But might have perceived that there was some strategy that would have increased the likelihood of winning

5. Seeing structure in randomness
One factor in acquiring false beliefs: tendency to see structure in randomness
We are very good at seeing meaningful patterns in the world
Useful and impressive ability!
But so pervasive and automatic... can sometimes lead us astray

6. Clustering illusion Distribution of bombs in London during WWII
Was Regent’s Park targeted?
No, just random

7. Clustering illusion These are randomly generated points
Our minds readily see structure in random

8. Home remedy: radishes!
Your friend’s remedy for common cold: eat large amounts of radishes
One day when you are really sick, the friend brings you a bunch of radishes to eat
You think: oh well, might as well try it
Next day: you are feeling a lot better!
Wow, do radishes really work?
Or … could this just be coincidence?
(sounds unlikely to you)

9. Spontaneous recovery
Health varies over time, semi-randomly, and most illnesses get better on their own
Seek treatment when health at low points
Likely to get better regardless of treatment
Misinterpretation of spontaneous recovery could lead to false beliefs about remedies

10. Summary - misperceived causation
We are very good at seeing patterns in the world and generating causal hypotheses
But this tendency can lead us to mistakenly see causal relations in randomness
Clustering illusion
Misinterpretation of streaks or clusters that occur naturally by chance
Regression fallacy
Misinterpretation of regression to the mean

12. Why do erroneous beliefs persist?
Suppose we have an false belief
Due to clustering, regression, coincidence ...
In principle, exposure to counterevidence might allow one to correct the error
However, some cognitive factors interfere with correction of false beliefs…

13. Neglect missing information…

14. Example: selection criteria
A manager at a company has unusual method for choosing who to hire
Top 8 candidates compete in chess tournament, winner gets the job
Manager:
“Everyone I’ve hired with this method has been excellent!”

15. Example: selection criteria
Hiring method: chess tournament
If previous employees performed well – does that mean that hiring method is good?
Or are we missing information?
Manager:
“Everyone I’ve hired with this method has been excellent!”

16. Example: selection criteria
Problem: missing data about how rejected candidates would have performed if hired
Only get feedback about the performance of candidates that were hired
If strong candidate pool, even flawed system would select good performers
Some rejected candidates might have been even better, but no way of knowing

17. Home remedy: radishes! (again)
Your friend convinced you that radishes are a good treatment for colds, which is false
Will you learn from experience that radishes do not really help?
Problem: missing information
If you belief in treatment, then every time you are sick you will eat radishes
Never get to see how quickly you would recover without radishes

18. Confirmatory evidence more noticeable…

19. What evidence is noticed?
Example: belief that your roommate never remembers to wash their dishes
Lots of relevant evidence – every meal at home, either does or does not wash dishes
But which cases will be noticed?

20. “Roommate never washes dishes”
Again??!
I need a new roommate!
Sunday
Monday
Tues
Weds
Thurs
Friday

21. What evidence is noticed?
Example: belief that your roommate never remembers to wash their dishes
Pos / neg evidence not equally noticeable
Salient evidence would only reinforce belief
Reinforce belief
(even if rare)
Going smoothly is non-event, not salient
Unpleasant event, highly salient!

22. Example: prophecy Using my psychic powers, I predict:
On the first day of Lunar New Year in 2013,
… there will be a major earthquake in China

23. Example: prophecy
Prophesy: On the first day of Lunar New Year in 2013, major earthquake in China
Specific, falsifiable prediction
But - what outcome would you notice?

24. Example: prophecy
Prophesy: On the first day of Lunar New Year in 2013, major earthquake in China
No earthquake
New Year
Non-event, unlikely
to remember prophesy
Earthquake!
New Year
WOW! He really is psychic!

25. Example: prophecy
Prophesy: On the first day of Lunar New Year in 2013, major earthquake in China
No earthquake
New Year
Noticeable outcome would confirm psychic powers, not disconfirm
Earthquake!
New Year
WOW! He really is psychic!

27. Bias in seeking information…

28. Exercise: rule discovery
Goal: to figure out an unknown rule for sequences of three numbers
Some sequences of numbers satisfy the rule, some sequences do not
Here is one sequence of numbers that satisfied the rule: 2-4-6
Now you can suggest numbers for testing
I will tell you “yes” or “no”

29. Exercise: rule discovery
Demo: test cases to discover rule
Initial example chosen so that you would likely have some guess about the rule
Tendency: test additional examples that would also satisfy rule
Problem: did not get opportunity to learn that your guess was wrong
Restricted test cases could only reinforce mistaken belief about rule

30. Application: medical diagnosis
How might confirmation bias lead to misdiagnosis by doctors?

31. Example: test for extroversion
Goal: scale for measuring extroversion
Items are self-reflective statements
“I often feel that …” “I generally do not …”
Each item is rated on scale agree/disagree
1 – ‘strongly agree’
2 – ‘agree’
3 – ‘neither agree not disagree’
4 – ‘disagree’
5 – ‘strongly disagree’
Exercise: everyone write down a possible item for an extroversion scale

32. Example: test for extroversion
In principle, items could test for either presence or absence of extroversion
Presence: “I am often the life of the party”
Extroverts would “agree”
Absence: “I often keep to myself at parties”
Extroverts would “disagree”
In your sample items, would extroverts be expected to agree or disagree?
Expected result: mostly “agree” items

33. Seeking confirmation
Extroversion test example: tended to seek information that confirms not disconfirms
Look for presence of a trait not absence
Look for +extroversion not -introversion
If asked to make a test for introversion, would have chosen different statements
… even though these are assumed to be opposites along the same continuum

34. Wason selection task
Hypothesis: “Cards with an odd number on one side have a circle on the other side”
Which cards need to be flipped to evaluate this hypothesis?

35. Wason selection task To evaluate hypothesis “if odd, then circle”
Typical answer: (a) and (c)
Correct answer: (a) and (d)

36. Wason selection task To evaluate hypothesis “if odd, then circle”
If not circle, would refute hypothesis
Does not matter
If odd, refutes
hypothesis
If odd, supports hypothesis
If even, does not refute!

37. Wason selection task To evaluate hypothesis “if odd, then circle”
If not circle, would refute hypothesis
Does not matter
If odd, refutes
hypothesis
Could only confirm, never refute

38. Wason selection task To evaluate hypothesis “if odd, then circle”
Obviously relevant
Obviously irrelevant
Incorrectly treated as
strong evidence
Relevant but neglected

39. Wason selection task Hypothesis: “If drinking beer, then over 18”
Which people need to be checked?
Logically, exactly same as previous, but people tend to get this version correct
“Permission” schema seems to help

40. Wason selection task Hypothesis: “If odd, then circle”
Logically, need to check: odd, square
But typically drawn to check circle card, which could confirm but never disconfirm
Confirmation bias in seeking information

41. Summary - Confirmation bias
When evaluating a belief, we tend to seek and focus on confirmatory information
As a result, less likely to be exposed to evidence that might refute a false belief
Example demonstrations:
Rule discovery exercise
Look for stereotypical extroverted traits
Wason selection task

42. Expectations influence interpretation of evidence…

43. Example: knowledge -> perception
Once you know what it is, looks different!
By R. C. James

44. Bias due to expectations
Bias due to expectations can allow us to interpret highly ambiguous information
Perceptual example: experience allows us to see Dalmatian from degraded image
Adaptive use of knowledge and experience
Is there a downside to this?
Potential problem: re-enforce false beliefs

45. Example: Referees’ judgments
Referees in sports often have to interpret ambiguous information to evaluate penalties
Susceptible to bias from expectations
High tackle or not?
Depends: are you an All-Blacks fan??

46. Example: Referees’ judgments
Frank & Gilovich (1988) –effect of black uniforms on referee judgments
Referees evaluated possible penalties from videos
Identical situations except varied uniform color
Finding: more penalties for players wearing black
Explanation: stereotype of black as “bad guy”

47. Lack of source memory…

48. Trivia quiz
Answer trivia quiz

49. Trivia quiz
Compute the number of “true” responses for even numbered statements
Actual: equal true/false
Even numbered statements were repeated from previous trivia quiz (if you took it)
Prediction: more “true” for statements that were repeated

50. Illusion of truth effect
Data from my HKU class:
For identical statements, more “true” judgments on second test
Percent judged “true”
Change due to just one prior exposure

51. Trivia quiz Why might there be a bias toward “true”?
Repeated statements were more familiar
General bias: familiar -> perceived true
“Validity effect” or “Illusion of truth effect”
Hasher, Goldstein, & Toppino (1977)
Example of a failure of source memory

52. Source memory Take some fact that you know is true:
“The largest ocean in the world is the Pacific Ocean”
How do you know this is true?
Can you answer: when and where did you learn this fact?
You know that this fact is true, but you don’t remember the source of knowledge
Hard!

53. Source memory Human memory is very good at recognition
… but memory is not as good for source
We know many things…
.. but not necessarily how we know

54. Source memory
Real life example where poor source memory might lead to persistent false beliefs?

55. Urban myths
Lack of source memory can explain persistence of “urban myths”
Suppose we have heard a myth many times
Hard to remember whether or not we heard from a reliable source
(Also, we don’t tend to question how we know something – we just do)
So if myth is familiar, tend to believe it
Then we might repeat the myth to others, increasing familiarity for them, and so on ...

56. Home remedy: radishes! I’ve discussed a false remedy: radishes
Right now, you remember that this is just a silly example for illustration
But years from now…
… may only remember hearing something about radishes curing the cold
Sorry for planting a future false belief!

58. Summary – persistence of false beliefs
Tend to seek confirmatory evidence
Neglect missing information
Confirmatory evidence more noticeable
Biased interpretation of evidence
Lack of source memory
Effect of these factors: can be very hard to change a false belief!

60. Avoiding bias? Try to consider possibility of coincidence
We tend to seek causal interpretations, and neglect the possibility of coincidence
Helpful to keep this in mind, and recognize some specific situations
eg. regression to mean

61. Avoiding bias? Be aware of missing information
Information required to evaluate a belief is often unavailable or unnoticeable
How well would rejected applicants have performed?
If roommate does reliably washes dishes, would I notice?
Would the condition have improved even without treatment?
Noticing these situations can cue you to be skeptical about beliefs

62. Avoiding bias? Be aware of limited source memory
We tend to perceive familiar as true
Try to reinforce good information more than bad information

63. Avoiding bias? Strategy: study science!
Thinking like a scientist can help overcome some of these biases
Idea of testing falsifiable predictions
Appreciation of randomness and statistics

64. Thanks for your attention