Conceptual and Perceptual S&V Ch 5: Looking for Truth in Personal Experience Illusions.

Conceptual and PerceptualConceptual and Perceptual

S&V Ch 5: Looking for Truth in Personal Experience

Illusions

The ArgumentThe Argument

• Perception, memory and “reason” are reliable but

not infallible.

• There are errors of reasoning and sensory

illusions to which all people are prone.

• But if we know about them we can avoid being

fooled.

ConceptsConcepts• Veridical and non-veridical experience

• Perception and memory as “constructive”

• Judgment: we can avoid being fooled!

• Conceptual Illusions: “Informal Fallacies” and other errors of judgment

• Denying the evidence

• Confirmation bias

• Representativeness heuristic (stereotyping) and implicit bias

• Conjunction fallacy

• How conditionals are falsified

• “Strength” of a proposition

Some Errors of JudgmentSome Errors of Judgment

• Denying the evidence

• Confirmation bias

• Representativeness heuristic (stereotyping) and implicit bias

• Conjunction fallacy

Angels of MonsAngels of Mons

Denying the EvidenceDenying the Evidence

Crop CirclesCrop Circles

More crop circlesMore crop circles

Confirmation BiasConfirmation Bias

A D 4 7

We look for evidence that confirms a hypothesis--and tend to ignore data that would falsify it

Hypothesis: If a card has a vowel on one side then it has an even number on the other

How do you determine the most effective means for deciding whether the hypothesis is correct or incorrect?

How do you determine the most effective means for deciding whether the hypothesis is correct or incorrect?

AA DD 44 77

Most subjects thought that only the A and 4 cards needed to be turned over.

Hypothesis: If a card has a vowel on one side then it has an even number on the other.Hypothesis: If a card has a vowel on one side then it has an even number on the other.

AA DD 44 77

22

Hypothesis: If a card has a vowel on one side then it has an even number on the other.Hypothesis: If a card has a vowel on one side then it has an even number on the other.

AA DD 44 77

22 EE

Hypothesis: If a card has a vowel on one side then it has an even number on the other.Hypothesis: If a card has a vowel on one side then it has an even number on the other.

AA DD 44 77

22 66 EE

Hypothesis: If a card has a vowel on one side then it has an even number on the other.Hypothesis: If a card has a vowel on one side then it has an even number on the other.

AA DD 44 77

22 66 EE II

Hypothesis: If a card has a vowel on one side then it has an even number on the other.Hypothesis: If a card has a vowel on one side then it has an even number on the other.

A D 4 7

An evennumber

supports thehypothesis

Turning thiscard is

completelypointless!

A vowelis consistent

with thehypothesis

A vowelfalsifies thehypothesis

conclusively

For future reference . . .For future reference . . .

The hypothesis we were testing was a CONDITIONAL--an if-then statement.

In a conditional the “if” clause is called the antecedent and the “then” clause is called the consequent, e.g.

If a card has a vowel on one side then it has an even number on the other.

A conditional is conclusively shown to be false if its antecedent is true and its consequent is false!

Representativeness Heuristic (stereotyping)

Representativeness Heuristic (stereotyping)

The Linda Problem: Linda is 31, single, outspoken and very bright. She majored in philosophy. As a student she was deeply concerned with issues of discrimination and social justice and also participated in antinuclear demonstrations.

Rank the following in order of likelihood:–Linda is an insurance salesperson–Linda is a bank teller–Linda is a bank teller and is active in the feminist movement

Bank Tellers Feminist Activists

Bank tellers who are feminist activists

Where’s Linda?Where’s Linda?

A and B can’t be more likelyA and B can’t be more likely

• Predicting A leaves it open whether it is or isn’t a B too.

• Predicting that it’s an A and B is riskier!

A’s B’s

Things that are both A and B

The Conjunction FallacyThe Conjunction Fallacy

1. Linda is a bank teller and Linda is active in the feminist

movement.

2. Linda is a bank teller

(1) can’t be more probable than (2) because it is “stronger,” i.e. conveys more information, than (2)

A conjunction (“and” statement) can never be more probable than one of its conjuncts!

Moral: In weakness there is strength!

Implicit BiasImplicit Bias

• Many cognitive processes that affect behavior are unconscious in nature and are inaccessible to observation by the actor.

• These implicit processes affect perception, influence behavior, and color interpretation of past events.

The Implicit Association TestThe Implicit Association Test

The IAT requires the rapid categorization of various stimulus objects, such that easier pairings (and faster responses) are interpreted as being more strongly associated in memory than more difficult pairings (slower responses).

The Implicit Association TestThe Implicit Association Test

• The IAT “measures the thumbprint of culture on our minds.”

– 88 percent of white people had a pro-white or anti-black implicit bias

– Nearly 83 percent of heterosexuals showed implicit biases for straight people over gays and lesbians

– More than two-thirds of non-Arab, non-Muslim volunteers displayed implicit biases against Arab Muslims.

The Implicit Association TestThe Implicit Association Test

• We all have the thumbprint of culture on our minds

– 48 percent of blacks showed a pro-white or anti-black bias

– 36 percent of Arab Muslims showed an anti-Muslim bias.

– 38 percent of gays and lesbians showed a bias for straight people over homosexuals.

Real World ConsequencesReal World Consequences

• The results of the IAT are confirmed by “real world” tests of biased behavior

• Economists at the Massachusetts Institute of Technology and the University of Chicago recently sent out 5,000 résumés to 1,250 employers who had help-wanted ads…Some applicants were given stereotypically white-sounding names such as Greg; others were given black-sounding names such as Tyrone…Every employer got four résumés: an average white applicant, an average black applicant, a highly skilled white applicant and a highly skilled black applicant.

Employers wanted minorities!Employers wanted minorities!

• Interviews beforehand with human resources managers at many companies in Boston and Chicago had led the economists to believe that black applicants would be more likely to get interview calls.

• Employers said they were hungry for qualified minorities and were aggressively seeking diversity.

Results of the ExperimentResults of the Experiment

• Résumés with white-sounding names triggered 50 percent more callbacks than résumés with black-sounding names.

• High-quality black résumés drew no more calls than the average black résumés.

• Highly skilled candidates with white names got more calls than average white candidates, but lower-skilled candidates with white names got many more callbacks than even highly skilled black applicants.

"Mind bugs operate without us being conscious of them. They are not special things that happen in our heart because we are evil."

Philosophy kills mind-bugs!Philosophy kills mind-bugs!

If we understand the “pecularities of our minds at work” we can factor them out and make correct judgments.

Don’t go with your gut!

Perceptual IllusionsPerceptual Illusions

Should we trust the evidence of the senses?

Things are not always as they seem…

Trust me--I’ma politician.

The morals to be drawn from the discussion that follows:

The morals to be drawn from the discussion that follows:

• Perception (and memory) are reliable but not infallible.

• Knowledge doesn’t require certainty--but we should know when to be careful.

• If we know what’s going on we can avoid being fooled.

Perception is constructivePerception is constructiveWhat we perceive is determined not only by the senses but by– What we know– What we expect– What we believe– What our psychological state is

When we should be carefulWhen we should be careful

• Our conclusions are at odds with all

known past experience

• Our experience is uncorroborated

• Peculiarities of our minds could be at

work

I never sawa purple cow

There’s is a first time for everythingThere’s is a first time for everything

Deceptive IllusionsDeceptive Illusions

ChecksChecks

…and more scintillating grids

Parallel lines?Parallel lines?

The Café Wall Illusion in motion

Poggendorff InteractivePoggendorff Interactive

The Poggendorff IllusionThe Poggendorff Illusion

What’s the illusion here?What’s the illusion here?

Here’s some more of the same…Here’s some more of the same…

Maybe you don’t believe me so

Munker-White IllusionMunker-White Illusion

Another color illusion…Another color illusion…

We see what we expect to seeWe see what we expect to see

We expect to see facesWe expect to see faces

Face on Mars,

Face in beans,

...and more faces

Ambiguity IllusionsAmbiguity Illusions

What animal?What animal?

Figure-ground ambiguityFigure-ground ambiguity

Rubin vaseRubin vase

Escher Face(s)Escher Face(s)

How old is she?How old is she?

Young Woman/Old WomanYoung Woman/Old Woman

Another young/old womanAnother young/old woman

So big…

size and size constancy

So big…

size and size constancy

Look familiar?Look familiar?

Müller-Lyer Illusion (interactive)

I’m not paranoid…I’m not paranoid…

Someone really is out to get meSomeone really is out to get me

Autokinetic effect:illusions of motionAutokinetic effect:illusions of motion

• UFOs

• The Rotating Snake (nausea

warning)

• Stepping Feet

Totally mad illusions!Totally mad illusions!

Close upClose up

The Greek versionThe Greek version

Impossible triangleImpossible triangle

Another impossible triangleAnother impossible triangle

Going nowhere fast…Going nowhere fast…

Escher stairsEscher stairs

Simpson StairsSimpson Stairs

Sim

pso

n S

tair

sS

imp

son

Sta

irs

TheEnd