cornell psych 205: day12

8/14/2019 Cornell Psych 205: day12

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Psychology 205Perception

Day 12

27 Feb 03


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Parapsychology

mediumship -- magicians vs. physicistspsychokinesis -- Uri Geller & James Randiprecognition -- seerstelepathy -- 1975, J.B. Rhine

AAAS accepts in 1969clairvoyance -- autoganzfeld experiments

case studies vs. scientific methodreplicability

probability & statistics - a priori - chance- a posteriori - base rate

Does use of the scientific method imply that theresearch is science?


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Why is extrasensory perception (ESP) interestingtheoretically?

1. the role of belief in science (and all of academia)

2. Johannes M llers Doctine :peripheral nervous system (PNS) --> CNSESP would bypass PNS

no known receptors

direct knowledge of the world without sensory information3. relation of scientific methods to science


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Scientific Methods

null hypothesis -- H 0experimental hypothesis -- H 1

Logic: 3 steps

1. devise situation for statistical test2. test H o; that is, assess its probability

3. if improbable, assume H 1 is truecriterion --> p < .05

if not improbable, assume H o is true

criterion --> p > .05


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One can never prove the experimental hypothesis true.

Results corroborate theories;they do not prove them true or false

Proof of truth is possible only in sufficiently closed systems,such as math and logic.

Why?


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Issues:

1. many H 1s (or H 1, H 2, H 3, H 4)There are an indefinitely large number of theories that can account for any set of data.

2. occurrence of logical error in step 3

.if improbable, assume H 1 is trueif not improbable, assume H 0 is true

Type 1 error - reject H 0 when it is trueType 2 error - accept H

0when it is false


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Example of multiple H 1s:

Linear induction 1, 2, 3, 4, 5, .....

k = place in sequence

n = number in that place


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Linear induction 1, 2, 3, 4, 5, .....

k = place in sequencen = number in that place

Theory 1: n = k = 6

Theory 2: n = (k-1)(k-2)(k-3)(k-4)(k-5) + k

= 126


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How to assess hypotheses (theories)

data (generated in some systematic way)

statistics (N>>1, not case studies)

our rhetorical devices


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The sign test:z = x - 0.5 - NP__

sqrt[NP (1-P)]

z = measure of distribution on a normal (bell-shaped) curve (like a standard deviation, sameunits as measured with d)

x = number of occurrences of a particular patternof interest

0.5 = "correction for continuity" (magic)N = number of observationsP = the a priori probability of that pattern

know this


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Examples: coin flips, expectation = 0.5 Heads 6/10 ---> z = 0.31 p ~ .75Heads 12/20 ---> z = 0.67 p ~ .50


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Examples: coin flips, expectation = 0.5 Heads 6/10 ---> z = 0.31 p ~ .75Heads 12/20 ---> z = 0.67 p ~ .50Heads 60/100 ---> z = 1.90 p < .055


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Examples: coin flips, expectation = 0.5 Heads 6/10 ---> z = 0.31 p ~ .75Heads 12/20 ---> z = 0.67 p ~ .50Heads 60/100 ---> z = 1.90 p < .055Heads 600/1000 --> z = 6.29 p < .0000001

Law of Large Numbers:likely occurrences converge rapidlytowards expected probabilities


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A Sample ESP Study


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sqrt[NP (1-P)]

z = x - 0.5 - N/10__sqrt[N*.1 *.9]

z = x - 0.5 - N/10__.9 sqrt[N]


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Reject H0 : null hypothesis is (incredibly) unlikely,assume null hypothesis is not true

Accept H 1 : ESPtelepathy

or something else?


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chance vs. base rate

a priori vs. a posteriori probabilities

example: live births, male or female


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chance vs. base rate

a priori vs. a posteriori probabilities

example: live births, male or femalechance: 50%base rate: ~52%


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stacking effect


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sqrt[NP (1-P)]

z = x - 0.5 - .28N__sqrt[N*.28* .72]

z = x - 0.5 -.28N__.45 * sqrt[N]


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Pick a number between 0 and 9, like 7

15% pick 715% pick 3


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R.D. Laing Knots (1974)

They are playing a game. They are playingat not playing a game. If I show them I seethey are, I shall break the rules I must play

their game of not seeing I see the game.


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Paraphrase of Laing

Professor Cutting is playing a game [of spontaneouschoices]. And he is also playing at not playing a game.If I show him I understand his game [of spontaneity], Ishall break the rules I must choose my spontaneouspattern carefully.


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One must be wary of stacked situations inmethodologies of all experiments, not just in thoseinvestigating the paranormal. Questionnaire studiesare particularly susceptible.

Another set of studies on clairvoyance

Autoganzfeld experimentsBem and Honorton, 1994results favor the existence of some form of psianomalous information transfer


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Methodology: not flawed

Results: more than reasonable toreject the null hypotheses

chance 25%results ~30-55%

does one have to accept the

experimental hypothesis of anomalous information transfer?

A framework


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Response Yes No

Yes Hit MissStimulus

No False CorrectAlarm Rejection


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Response Yes No

Yes Hit MissStimulus No False Correct

Alarm Rejection

Experimental results

positive negative(H o rejected) (H o accepted)

Exists "progress" Type II errorPhenomenon

Does Not Exist Type I error not part of science


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Experimental resultspositive negative

(H o rejected) (H o accepted)

Exists psi exists Type II errorPhenomenon

Does Not Exist Type I error ------


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Type I error - one says the phenomenonexists, but it doesnt [false alarm]

Type II error - one says the phenomenon doesnot exist, but it does [miss]

the practice of science deplores (has a bias against)Type I errors when a result does not mesh with anexisting fabric of logic and research;

in such situations it would rather make Type II errors

Why?


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what are therelativecosts?

not settlable, yeta different venue


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How to chose among theories ?

Thomas Kuhn (1977)

Theories should be:

1. accurate in predictions(across replications)

2. relatively simple3. broad in scope4. internally consistent5. able to generate new research and

new findings


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Theories should be:

1. accurate in predictions(across replications)*2. relatively simple --> linear induction3. broad in scope4. internally consistent

*5. able to generate new research andnew findings


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We are on the verge of breakthroughs in psychical phenomena.--- William James, 1890


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We are on the verge of vast development in psychic research.--- Lord Rayleigh, 1919


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We are on the verge of vast development in psychic research.--- Lord Rayleigh, 1919

Parapsychology appears ready to make startling advances.--- Time Magazine, 1974


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Parapsychology


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Parapsychology

mediumship -- magicians vs. physicists --> not fashionablepsychokinesis -- Uri Geller & James Randi --> not fashionable precognition -- seers --> not fashionable, outside of

supermarket checkout lines telepathy -- 1975, J.B. Rhine --> not fashionable

AAAS accepts in 1969

clairvoyance -- autoganzfeld experiments --> fashionable

case studies vs. scientific methodreplicabilityprobability & statistics - a priori - chance

- a posteriori - base rate--> role of belief in science

Does use of the scientific method imply that the research is science?

cornell psych 205: day12

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