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Cognitive Biases 2 Confirmation Bias. COURSE REVIEW.

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Presentation on theme: "Cognitive Biases 2 Confirmation Bias. COURSE REVIEW."— Presentation transcript:

1 Cognitive Biases 2 Confirmation Bias

2 COURSE REVIEW

3 Course Instructor

4 Office: HSH (Ho Sin Hang) 213

5 Office Hours Friday 14:00-16:00

6 My gmail.com

7 Course Website michaeljohnsonphilosophy.com

8 Course Meeting Times Tuesday 15:00-16:30 LKK 103 Friday 9:30-11:00 LKK G05

9 ASSESSMENT

10 Reading There is no required reading in this class. There is lots of optional reading on the course website. I may give bonus marks to students who can answer questions in class about the optional reading!

11 Assessment 10 short homework assignments, each 6 marks, for a total of 60 marks. Attendance: 10 marks Participation: 10 marks 1 final exam, worth 20 marks

12 Short Homework Assignments Every week we will have a homework assignment where you apply what weve learned that week. Example…

13 Out of Context

14 In Context

15 HW1 Find an example, from your own life and experiences, where a piece of information was taken out of context in a misleading way.

16 Rubric Describe the information taken out of context: 1 mark Describe the claim the information was used to support, and who was making the claim: 2 marks Describe the broader context and why the information presented was misleading: 2 marks Students own experience: 1 mark

17 Late Assignments I wont accept late homework. Even 1 minute late is late. Sorry.

18 Participation Participation is just like HW1. You cannot get an A in this course if you do not participate. I will give you 1 mark for every (good) example up to 10 marks.

19 Attendance Attendance is required and accounts for 10% of your final grade. You cannot get an A in this course if you do not attend classes. Every day you dont attend, you lose 0.5 marks off your final grade, up to a maximum of 10.

20 Late to Class You will not be counted as present if you show up after I have called attendance. Please be in class on time.

21 Final Exam The final exam will happen during the scheduled exam period. Exact time/ date TBA. It will consist of short answer questions and involve application of critical thinking skills. It is worth 20 marks.

22 Curve Based Grading

23 SUBJECT REVIEW

24 Critical Thinking Is there any evidence to support the claim? Is the evidence reliable and trustworthy? How reliable is it? Should you accept it? Does the evidence actually support the claim? Is there other evidence you should consider?

25 Critical Thinking and Skepticism Skepticism [critical thinking]… is essentially a form of basic intellectual hygiene, something that everyone is capable of to varying degrees and something that everyone should do. -- Chris Clarke

26 Critical Thinking as Mental Hygiene Skepticism is to the intellect as brushing is to teeth. Sometimes we need expert assistance, but the only way it really does us any long term good is if we engage in the practice of mental hygiene as a habit, preferably after each bout of consuming something that might cause problems down the road, whether its a bag of chips or an article in the New York Toast.

27 Difference There is one thing where skepticism differs from toothbrushing. There arent legions of non-toothbrushers who pour support and money towards cranks that tell them to keep their mouths dirty. – vaiyt (Comment #20)

28 WASON SELECTION TASK

29 Even vs. Odd Even numbers: 2, 4, 6, 8, 10, 12… Odd numbers: 1, 3, 5, 7, 9, 11, 13…

30 Wason Selection Task Suppose that I present you with four cards. On each card there is a number on one side and a color (blue or red) on the other. I claim: If a card has an even number on one side then it is blue on the other side. Which of the four cards do you need to turn over to tell whether this claim is true or false?

31 A B C D

32 Results!

33 Wason Selection Task Card A doesnt matter. First possibility: 1. The other side is blue. The claim says if its even, then its blue. It does not say that if its not even, then it is not blue.

34 Example True claim: if a student makes an appointment, she can see me in my office. Does not mean false claim: if a student does not make an appointment, she cannot see me in my office.

35 Wason Selection Task Card A doesnt matter. Second possibility: 2. The other side is red. The claim says even cards cant be red. It does not say odd cards cant be red.

36 A B C D

37 Wason Selection Task Card D doesnt matter. Two possibilities: 1. The other side is even (for example, its 4). The claim says if its even, then its blue. It does not say that if its blue, then its even.

38 Example True claim: If something is a dog, then it is an animal. Does not mean false claim: if something is an animal, then it is a dog.

39 Wason Selection Task Card D doesnt matter. Two possibilities: 2. The other side is odd (for example, its 3). The claim says if its even, then its blue. It does not say that if its not even, then it is not blue.

40 A B C D

41 Wason Selection Task Card B is important. 4 is an even number. If other side of card B is red, then the claim is false, because B is a card with an even number on one side but it is not blue on the other side. You must turn over B and make sure it is not red on the other side.

42 A B C D

43 Wason Selection Task Card C is also important. If the claim is true, this card must have an odd number on the other side. If it has an even number on the other side, then the claim is false. You must turn over #3 and make sure there is not an odd number on the other side.

44 Statistical Results Around ½ of people studied say B: 4 and D: Blue. About 1/3 say just B: 4. Only about 1/20 get the right answer: B: 4 and C: Red!

45 Analysis People look for results that would agree with the claim. Turning over B and D, you could get agreement– for example, [4, Blue] and [6, Blue]. You cannot get agreement by turning over C. But you can get disagreement and that is why the card is important!

46

47 CONFIRMATION BIAS

48 Confirmation Bias People tend to look for evidence that agrees with what they already believe. This is called confirmation bias.

49 Bacon on Confirmation Bias The human understanding when it has once adopted an opinion… draws all things else to support and agree with it. And though there be a greater number and weight of instances to be found on the other side, yet these it either neglects and despises, or else by some distinction sets aside and rejects; in order that by this great and pernicious predetermination the authority of its former conclusions may remain inviolate. – Sir Francis Bacon

50

51 Confirmation Bias Confirmation bias is perhaps the best known and most widely accepted notion of inferential error to come out of the literature on human reasoning. (Evans, 1989, p. 41)

52 Confirmation Bias Many have written about this bias, and it appears to be sufficiently strong and pervasive that one is led to wonder whether the bias, by itself, might account for a significant fraction of the disputes, altercations, and misunderstandings that occur among individuals, groups, and nations. – Nickerson 1998

53 Its Ordinary Your day might start on a sour note: you wake up late, the barista screws up your coffee (even after youve waited forever in line), your car wont start again. If you mentally set yourself up to say This is a bad day, you will look for further evidence to support that notion throughout your day, potentially ignoring evidence that its a day like any other or maybe even a good day overall. -- Satya Putumbaka

54

55 Fish vs. Obama Theres no mistaking whats going on in the speech delivered last week. No preliminary niceties; just a rehearsal of Obamas actions and expectations. Eight Is right off the bat: -- Stanley Fish

56 Is Just over two months ago I spoke with you… and I laid out what needed to be done. From the beginning I made it clear that I would not put any more tax dollars on the line. I refused to let those companies become permanent wards of the state. I refused to kick the can down the road. But I also recognized the importance of a viable auto industry. I decided then…

57 Presidential Pronouns US PresidentIme myTotal Obama 1 st Press Conf. 2.10%0.55%2.65% Bush Jr. 1 st 2 Press Conf. 3.58%0.91%4.49% Clinton 1st 2 Press Conf. 3.14%0.73%3.87%

58 Stereotypes Stereotypes are another instance where our expectations lead us into the wrong beliefs.

59 A Strange Example Americans were asked: Which of these pairs of countries are more similar to one another? 1.West Germany, East Germany 2.Sri Lanka, Nepal

60 They said (1), West Germany and East Germany. Others (Americans) were also asked: Which of these pairs of countries are more different from one another? 1.West Germany, East Germany 2.Sri Lanka, Nepal

61 They also said (1). Americans thought that West Germany and East Germany were both more similar to each other than Sri Lanka and Nepal and less similar to each other than Sri Lanka and Nepal. How is that possible?

62 First, when considering the question which are more similar? the subjects looked for all the positive evidence that West Germany and East Germany were similar, and all the positive evidence that Sri Lanka and Nepal were similar. Since Americans know nothing about Asian countries, they had no positive reason to think Sri Lanka and Nepal were similar.

63 Similarly, when asked which are more different? the subjects considered the positive evidence that West Germany and East Germany were different and the positive evidence that Sri Lanka and Nepal were different. Again, having no knowledge of Sri Lanka or Nepal, Americans chose (1), because of all the positive evidence in its favor.

64 But it cannot be true that East Germany and West Germany are both more similar and more different than Sri Lanka and Nepal. What the subjects did not do is consider the relevant negative evidence that would disconfirm their hypotheses.


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