Thinking Like a ScientistModule 4: The Need for Psychological Science

Limits of Intuition• Do the following simple addition problem in your head:• Start with 1000 and add 40 to it.• Add another 30 followed by another 1000.• Next add 20.• Add another 1000.• Add 10• What is the number?• 5000?• WRONG! It’s 4100

Let’s do the Math…

• 1000 + 40 = 1040• 1040 + 1000 = 2040• 2040 + 30 = 2070• 2070 + 1000 = 3070• 3070 + 20 = 3090• 3090 + 1000 = 4090• 4090 + 10 = 4100• Your mind sometimes jumps to the wrong

conclusion!

How scientific are you?• If you drop a bullet off a table 3 feet high, and fire another

one straight across an empty football field, which hits the ground first?– Bullets hit at the same time because downward velocity is

independent of horizontal velocity.

• A ball rolls down a spiral track. The end of the track curves left. What path does the ball take when it leaves the track?– It follows a straight line to the left. Only objects acted on by a

constant lateral force curve.

Common Sense

• Conclusions based solely on personal experience and sensible logic

• Typically describes what has happened rather than what will happen

• Can lead to incorrect conclusions because:– People interpret what common sense means differently– You may be missing important information that would

help you come to a reasonable conclusion

Did you know…

• It is nearly impossible to fold a regular sheet of paper in half more than 7 times.

• Go ahead and try!

• Mythbusters pulled it off with a piece of paper as big as an airplane hanger and a steam roller. (4 min)

Science vs. Common Sense• Science helps build explanations that are

consistent and predictive rather than conflicting and describing the past (hindsight)

• Science is based on– knowledge of facts– developing theories – testing hypotheses– public and repeatable procedures

• Common Sense is based on prior experience

BOREDOM BUSTER!

Common Sense tells us squirrels are harmless…

OR ARE THEY?

RUNNING OF THE SQUIRRELS

Hindsight Bias• The “I knew it all along” phenomenon.

• The Tendency to exaggerate one’s ability to have foreseen how something would turn out after learning the outcome.

• You forget that previously you unsure how things would turn out and think instead you always knew what the outcome would be.

• 3 Level Process:

1. Memory distortion, involves misremembering an earlier opinion or judgment (“I said it would happen”).

2. Inevitability, centers on our belief that the event was inevitable (“It had to happen”).

3. Foreseeability, involves the belief that we personally could have foreseen the event (“I knew it would happen”).

EXAMPLE: You get an acceptance letter from college and say, “I knew I’d get in.” but in reality a week ago you were telling your friends how nervous you were that you hadn’t heard from the college yet.

Overconfidence

• Tendency to overestimate the accuracy of our current knowledge• We are more confident than we are correct.

– How long will it take you to do your homework? – Do you tend to underestimate how long it takes? - Overconfidence is why!

• “Man will never reach the moon, regardless of all future scientific advances.” - Lee DeForest, inventor of vacuum tube, 1957

• “Nuclear powered vacuum cleaners will probably be a reality within 10 years.” - Alex Lewyt, manufacturer of vacuum cleaners, 1955

• “Reagan doesn’t have the presidential look.” - United Artist Executive in turning Reagan down for the starring role in The Best Man, 1964.

What are the Odds of Each?

What are the Odds of Each?

1 in 2,598,960

What are the Odds of Each?

1 in 2,598,960 1 in 2,598,960

Perceiving Order in Random Events• We are naturally programmed to look for patterns.

• Random sequences often don’t look random

• Prior events don’t determine future outcomes

• With a large enough sample, the impossible become inevitable.– Given the billions of events that occur each day and given enough days, some

stunning coincidences are sure to occur

Virginia couple wins lottery 3 times in one month!

5 Common Types of CoincidenceCompiled by The Winton Programme for the Public Understanding of Risk

1. Surprising Repetitions– Multiple members of the same family who are born with the same birthday

2. Simultaneous Events– 2 people who phone each other at the exactly the same time

3. Parallel Lives– 2 people in a small group who share a birthday or an unusual name

4. Uncanny Patterns– Picking letters in Scrabble that spell your name

5. Unlikely Chains of Events– Losing false teeth overboard and finding them inside a fish you caught 20

years later

Confirmation Bias

• Our tendency to search for information that confirms our beliefs & ignore evidence that disputes our beliefs.

• Try this card trick: http://www.caveofmagic.com/• This works because we only look for our chosen card

confirming Simeon’s mental telepathy and ignore the fact that second set of cards is in fact, an entirely new set!

• NONE of the cards in the new set is the same as the old one so of course the card you picked is missing.

The Rat is Always Right

• Scientists need to be:– Curious – striving to explore and understand– Skeptical – Always ask…

• What do you mean?

• How do you know?

– Humble – be willing to admit when the evidence shows we’re wrong.

How Do They Know That?!Thinking Critically

• Don’t blindly accept arguments and conclusions

• Look for evidence gathered scientifically

• Who is providing the evidence? Are they biased?

• Are the right conclusions being drawn?

DAILY

DOUBLE

QUESTIONWhat is the difference between Common Sense and Science?

ANSWER:

Common sense relies on the past and may be wrong.

Science uses facts to provide consistent predictions