The Need for The Need for Psychological SciencePsychological Science

AP PsychologyAP Psychology

Ms. DesgrosellierMs. Desgrosellier

9.22.20099.22.2009

ObjectivesObjectives

SWBAT describe SWBAT describe hindsight biashindsight bias, , and explain how it can make and explain how it can make research findings seem like mere research findings seem like mere common sense.common sense.

SWBAT describe how SWBAT describe how overconfidence contaminates our overconfidence contaminates our everyday judgmentseveryday judgments

Why research in Why research in Psychology?Psychology? Is psychology just documenting what Is psychology just documenting what

we already know?we already know? People put a lot of faith in their intuitionPeople put a lot of faith in their intuition Intuition and common sense have their Intuition and common sense have their

limitslimits e.g. Imagine folding a sheet of paper on e.g. Imagine folding a sheet of paper on

itself 100 times. Roughly how thick itself 100 times. Roughly how thick would it be?would it be?

A: If the paper is .1 mm thick, after 100 A: If the paper is .1 mm thick, after 100 folds, it would be 800 trillion times the folds, it would be 800 trillion times the distance between the Earth and the distance between the Earth and the Sun.Sun.

Hindsight BiasHindsight Bias

The tendency to believe, after The tendency to believe, after learning an outcome, the one learning an outcome, the one would have foreseen it (aka the would have foreseen it (aka the I-I-knew-it-all-along phenomenonknew-it-all-along phenomenon))

e.g. Pretend you’re trying to e.g. Pretend you’re trying to decide who to invite to decide who to invite to homecoming. homecoming.

We have a harder time We have a harder time remembering when we’re wrong remembering when we’re wrong than when we’re right.than when we’re right.

Why do we need Why do we need psychological psychological research?research? We commonly make errors in our We commonly make errors in our

recollections and explanationsrecollections and explanations Common sense is usually after Common sense is usually after

the fact (made in hindsight)the fact (made in hindsight) Over 100 studies have observed Over 100 studies have observed

hindsight bias in various countries hindsight bias in various countries and among both children and and among both children and adultsadults

Psychology’s findingsPsychology’s findings

Some are intuitiveSome are intuitive Others are notOthers are not Research both inspires and Research both inspires and

overturns popular ideasoverturns popular ideas

True or false?True or false?

Patients whose brains are surgically split Patients whose brains are surgically split down the middle survive and function down the middle survive and function much as they did before the surgery much as they did before the surgery

Most infants recognize their own Most infants recognize their own reflection in a mirror by the end of their reflection in a mirror by the end of their first yearfirst year

Most abused children do not become Most abused children do not become abusive adultsabusive adults

Fears of harmless objects, such as Fears of harmless objects, such as flowers, are just as easy to acquire fears flowers, are just as easy to acquire fears of potentially dangerous objects, such as of potentially dangerous objects, such as snakes snakes

OverconfidenceOverconfidence

We tend to think we know more We tend to think we know more than we do.than we do.

We also tend to be more We also tend to be more confident than correctconfident than correct

Test yourself!Test yourself!

How long do you think it would take How long do you think it would take you to solve the following you to solve the following anagrams?anagrams?– WREAT --> WATERWREAT --> WATER– ETRYN --> ENTRYETRYN --> ENTRY– GRABE --> BARGEGRABE --> BARGE

Most people said around 10 secondsMost people said around 10 seconds Now, try to solve: RABDONow, try to solve: RABDO In reality, closer to 3 minutesIn reality, closer to 3 minutes

Robert Vallone, et al. Robert Vallone, et al. (1990)(1990) Had college students predict at the beginning Had college students predict at the beginning

of the year whether they would drop a of the year whether they would drop a course, vote in an upcoming election, call course, vote in an upcoming election, call their parents more than twice a month, etc. their parents more than twice a month, etc.

On average, students felt 84% confident in On average, students felt 84% confident in making these self-predictionsmaking these self-predictions– e.g. I am 84% sure I will vote in the upcoming e.g. I am 84% sure I will vote in the upcoming

electionelection Later data collected showed that their Later data collected showed that their

predictions were only correct 71% of the timepredictions were only correct 71% of the time Even when they were 100% confident, they Even when they were 100% confident, they

were only correct 85% of the timewere only correct 85% of the time

Philip Tetlock (1998)Philip Tetlock (1998)

Collected data from professionals (i.e. Collected data from professionals (i.e. analysts, government experts, journalists)analysts, government experts, journalists)

On political, economic, and military On political, economic, and military situations e.g. Project how South Africa situations e.g. Project how South Africa will be governed: will be governed: – After 5 years, had them reflect on their After 5 years, had them reflect on their

predictions (South Africa is a multiracial predictions (South Africa is a multiracial democracy)democracy)

– 80% confidence were right less than 40% of 80% confidence were right less than 40% of the timethe time

– Even those who erred were likely to say that Even those who erred were likely to say that they were “basically” or “almost” rightthey were “basically” or “almost” right

– Bottom line: overconfidence is hard to Bottom line: overconfidence is hard to disprove or dislodge, no matter the actual disprove or dislodge, no matter the actual outcomeoutcome

Remember:Remember:

Hindsight bias and Hindsight bias and overconfidence often lead us to overconfidence often lead us to overestimate our intuition.overestimate our intuition.

Scientific inquiry can help us Scientific inquiry can help us separate reality from illusions.separate reality from illusions.