PHI2100 EXAM 2 IN CLASS ONLINE LECTURE OUTLINE SUMMARIES How We Protect Our Pet Beliefs Part I OUTLINE PET BELIEFS Beliefs we have that we may still hold even when we know evidence suggests AGAINST the Pet Belief Often has emotional attachments in belief We often protect our pet beliefs by finessing choosing focusing on certain data 1 Representativeness Heuristic We tend to make judgments by using stereotypes Stereotypes Usually havenegative connotation But can be useful in making quick decisions Ex If you see an Angry bear Don t wait to meet bear RUN Ex Person wears a suit carries a briefcase Major Probably Business a RH Clustering Illusion Our stereotype of random sequences Not many streaks ACTUALLY random sequences Random anything is possible b RH Base Rate Paradox All of Population factors must be taken into account to make accurate judgement c RH Conjuction Fallacy Linda is 31 years old participated in antinuclear demonstrations in college Please rank the following statements by their probability using 1 for the most probable and 3 for the least probable A Linda is active in the feminist movement in the feminist movement B Linda is a bank teller C Linda is a bank teller and is active ANSWER Linda does not sound like a stereotypical bank teller BUT there are more Bank Tellers than feminists SO Answer is B Conjunction fallacy A more specific demanding description that fits our stereotype will be seen as more probable than a less specific demanding description that does not fit our stereotype Lesson We are very good at giving convincing but unsupported explanations for things after they occur Mary has hot hands She makes her next two shots Success breeds confidence which breeds success which breeds confidence Mary has hot hands She misses her next two shots She got overconfident She s cooling off These easy explanations often give you a FALSE sense of understanding You should always ask yourself 1 Consider the opposite If something else had occurred could I have explained that too 2 Prediction Could I have predicted this BEFORE it happened If NO Probably an easy explanation that offers a false sense of understanding 3 Regression Fallacy We often explain regression effects with unnecessary causal factors a Regression to the mean Whenever occurrences of X vary around a mean if X1 is extreme X2 is likely to be closer to mean Quack cures Punishment Reward o Israeli Air Force o Coaching Parenting 4 Convenient Memory Availability Heuristic We tend to think events are more probable to the extent they are more available to memory Our memory is selective We remember things that are VIVID or DRAMATIC or ANNOYING or FIT W OUR THEORIES 5 Biased Interpretation We often interpret data that contradicts our pet beliefs as BAD LUCK or as ALMOST CONFIRMING our views How We Protect Our Pet Beliefs II OUTLINE 6 Fortune Cookie Problem No specific prediction NO experience would disconfirm your pet belief Hot hands children resemble their parents No time frame Bad things happen in threes Vague Bad things happen in 3 s Fortune teller pp 60 1 7 Social factors Biased information unrepresentative sample a Politeness People seldom tell you how your interpersonal strategies are failing b Birds of a feather We tend to associate with people who agree w us Second hand testimony Essential to our knowledge of the world Testimony is sharpened main point is over emphasized Testimony is levelled context details qualifications are de emphasized or ignored Consequence of sharpening levelling Second hand info produces more extreme views than first hand experience 8 Optional Stopping Take an issue that is important to you politics abortion religion affirmative action etc Are you equally critical of reasons that tend to support your view as you are of reasons that tend to undermine your view PROBABLY NOT NOTE You re not IGNORING negative evidence RATHER You are treating negative positive evidence DIFFERENTLY Our mistake is much more subtle than just ignoring evidence We finesse the evidence so as to protect our pet beliefs 9 Sample size paradox or Why Amazing Coincidences Aren t Really So Amazing In a large enough sample extremely low probability events will happen A LOT 1 Mutations are very rare Some creationists say Therefore evolution cannot have come about by mutations It s true About 1 100 000 genes are mutants But Each of us has about one billion genes So each of us has about 10 000 mutant genes 10 Understanding Chance 1 Law of Large Numbers Larger well chosen samples are more representative of a population than smaller samples 2 Frequency vs Absolute spread Suppose we flip a coin 1 2 3 4 5 times Over time The frequency of heads tails will tend toward 50 But the absolute spread the difference between the of H s the of T s will not necessarily be exactly 50 Just because 10 heads come out doesn t mean the next toss will have a greater lesser chance of being heads tails If something has a certain statistical propensity that will be reflected in its long run frequency A fair coin has a tendency to come up Heads Tails 50 of the time in the long run Our Statistical World OUTLINE In our everyday lives most of the world that we re interested in is RANDOM STATISTICAL Fundamentally random Event E s occurrence is indeterminate This might be true but isn t the main point Epistemically random Event E s occurrence can t be predicted beforehand Examples 1 Sports Pet Belief The world of sports is a world of streaks Hot hands cold hands in basketball Result Statistical analyses show that recent history is irrelevant to predicting shots in basketball hits in baseball H 51 HH 50 HHH 47 MMM 56 2 Clusters Do hits misses cluster more than would be expected statistically NO For a team that hits about 50 of its shots the clusters are just what you d expect if you were flipping a coin 2 Human performance music sports cooking teaching test taking interviewing etc People don t perform the same all the time But they tend to perform around their mean 3 Health When people are getting very sick or very sick getting better Before influences how we view After 4 Social world Almost ALL our explanations for people s behaviors are AFTER THE FACT These typically result in a false sense of understanding When Tom was 11 he ran away from home When he was 22 he joined the Peace Corps Can you explain it When Tom was 11 he ran away from home When he was 22 he committed suicide Can you explain it You can Probably explain both 5 Financial world The stock