Cognitive Biases 2 Confirmation Bias
Office Hours Friday 14:00-16:00
My Email email@example.com
Course Website michaeljohnsonphilosophy.com
Course Meeting Times Tuesday 15:00-16:30 LKK 103 Friday 9:30-11:00 LKK G05
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!
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
Short Homework Assignments Every week we will have a homework assignment where you apply what we’ve learned that week. Example…
HW1 Find an example, from your own life and experiences, where a piece of information was taken out of context in a misleading way.
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
Late Assignments I won’t accept late homework. Even 1 minute late is late. Sorry.
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.
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 don’t attend, you lose 0.5 marks off your final grade, up to a maximum of 10.
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.
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.
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?
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
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 it’s a bag of chips or an article in the New York Toast.”
Difference “There is one thing where skepticism differs from toothbrushing. There aren’t legions of non-toothbrushers who pour support and money towards cranks that tell them to keep their mouths dirty.” – vaiyt (Comment #20)
Even vs. Odd Even numbers: 2, 4, 6, 8, 10, 12… Odd numbers: 1, 3, 5, 7, 9, 11, 13…
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 blueon the other side. Which of the four cards do you need to turn over to tell whether this claim is true or false?
C D B A
Wason Selection Task Card Adoesn’t matter. First possibility: 1. The other side is blue. The claim says if it’s even, then it’s blue. It does not say that if it’s not even, then it is not blue.
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.
Wason Selection Task Card Adoesn’t matter. Second possibility: 2. The other side is red. The claim says even cards can’t be red. It does not say odd cards can’t be red.
C D B A
Wason Selection Task Card D doesn’t matter. Two possibilities: 1. The other side is even (for example, it’s “4”). The claim says if it’s even, then it’s blue. It does not say that if it’s blue, then it’s even.
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.
Wason Selection Task Card D doesn’t matter. Two possibilities: 2. The other side is odd (for example, it’s “3”). The claim says if it’s even, then it’s blue. It does not say that if it’s not even, then it is not blue.
C D B A
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.
C D B A
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.
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”!
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!
Confirmation Bias People tend to look for evidence that agrees with what they already believe. This is called confirmation bias.
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