Neglect base rates in bayesian reasoning?

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What do Bayesian's argue?
Probability refers to a subjective degree of confidence, and because one can express confidence that single event will occur one can express the probability of a single event
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What is base rate neglect?
Base rate neglect is a cognitive error, whereby, too little weight is placed on the base rate of possibility. A person has some own knowledge, known as individuating information, and then they have general information, base rate
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When presented with both pieces of information, what do people base their judgements on?
The individuating information and underutilize or completely ignore base rate evidence. Ignoring the base rate evidence in intuitive judgements and decision making is the base rate neglect
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What does a psychologist ask?
Whether people's reasoning about the probabilities is just normative, are asking whether the output of a system is the same that would be returned by a bayesian machine, not whether the internal process is bayesian
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What do evolutionary psychologists believe?
We can reason according to Bayes theroem, if information is presented in a format that we have evolved to process
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What was the demonstration first done by?
Tversky and Kahneman (1973)
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What is single case judgement?
People are more likely to neglect the base rate when making a single judgement of an event with only one base rate. It's the judgement of the probability of that single event and because there is nothing else to compare it to
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The base rate of the event gets what?
Overlooked compared to individuating information
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What is paragraph 1?
Representativeness Heuristic (Kahneman and Tversky, 1972)
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The better one is to fit an individualistic stereotype what?
One is more likely to neglect base rate in return for using their own individualistic information
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K and T (1973)
where there was a mixture of Lawyers and Engineers (1000 people tested and there was 5 engineers and 955 laywers). One was picked randomly and his description was read out for people to guess if he was a lawyer or engineer.
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What did people use in this?
People use their knowledge about the characteristics of engineer and lawyers
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Why is the representativeness heursitic better?
stereotype of one of the two professions, the more likely one is to assume that they are that profession. (EG: Jack is not married, likes reading science fiction, is somewhat introverted and likes to write computer programs - engineer
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If people used base rate then they would what?
estimated the chances of him being an engineer over the whole sample (5/100).
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What is the conclusion?
People fail to condition their probability estimates on provided base rates due to stronger individualistic information – thus providing base rate neglect
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What is the second paragraph?
Internal beliefs
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What are internal beliefs?
Your own beliefs are stronger and so lose out out in an internal conflict with base rate information given by someone else
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Penny cook et al?
Asked people to consider a set of base rate problems and either rely on their beliefs or on statistics. REsults showed that base rates affected posterior posibility
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What does this suggest?
This suggests that the processing of base rates has an intuitive character which does not require conscious deliberation and competes with belief for ultimate control.
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Dependeing on what?
how strong your own beliefs are in regard to the probability problem, depends on if base rates are neglected or considered
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What is the third paragraph?
Time constraints
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Under timed conditions base rate is what?
Prominent
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What did preference rehearsals lead to?
Reduce base rate neglect
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Tunny 2006?
timed conditions subjects lacked preference reversals, therefore opting for base rate neglect instead
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Goodie and Fantino
showed that base rate neglect disappears following exposure to outcomes (ie experiencing natural frequencies) but under time pressures, base rate neglect returns
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What is the paragraph 4?
Format of the problem can change what info the person chooses to use
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What is visual representation?
• Bayesian Reasoning benefits from the use of visual representations. If the problem is set out in a visual manner, than the person is more likely to use the information provided and therefore use the base rate.
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What is used?
Euler circles, frequency grids or trees
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Grgerenzer and Hoffrage?
They argued that Bayesian computations need fewer steps when presented in a frequency format. This means that fewer pieces of information are needed to be stored. Therefore, base rates are not needed in probability formats.
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For example?
You dont need to know how often the disease occurs in the population
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Cosmides and Tooby?
They found that probability problems in a particular format (frequency format) reduces base rate neglect. However, Griffin &Beuhler (1999) and Evans et al (2000) could not replicate this.
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Other cards in this set

Card 2

Front

What is base rate neglect?

Back

Base rate neglect is a cognitive error, whereby, too little weight is placed on the base rate of possibility. A person has some own knowledge, known as individuating information, and then they have general information, base rate

Card 3

Front

When presented with both pieces of information, what do people base their judgements on?

Back

Preview of the front of card 3

Card 4

Front

What does a psychologist ask?

Back

Preview of the front of card 4

Card 5

Front

What do evolutionary psychologists believe?

Back

Preview of the front of card 5
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