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Jan Noyes Professor of Human Factors Psychology University of Bristol http://human-factors.psy.bris.ac.uk/

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Jan Noyes Professor of Human Factors Psychology University of Bristol http://human-factors.psy.bris.ac.uk/ Integrated Uncertainty Modelling for Decision Making Workshop – PowerPoint PPT presentation

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Title: Jan Noyes Professor of Human Factors Psychology University of Bristol http://human-factors.psy.bris.ac.uk/


1
Jan NoyesProfessor of Human Factors
PsychologyUniversity of Bristolhttp//human-fac
tors.psy.bris.ac.uk/
Integrated Uncertainty Modelling for Decision
Making Workshop
2
Outline
  • Humans as information processors
  • Decision making as explained by reasoning
  • Risk perception
  • The study of human decision making over the
    decades
  • Influences on decision making
  • Summing up how do humans make decisions
  • Conclusions especially with regard to uncertainty

3
Humans as information processors
4
Our strengths
  • PerceptionThe process of receiving information
    from the outside world.
  • Note humans are furious pattern-matchers
  • Memory - an interesting paradox
  • Humans have amazing memories but also severe
    limitations on the amount of information they can
    process at any one time, for example, short term
    memory is fragile and limited, and effort is
    required to retrieve information.

5
Year Car Registration Colour
1947 Ford 8 ETA242 Black
1953 Morris Minor RTT859 Blue
1957 Morris Minor VOD236 Turquoise
1959 Ford Prefect 496FAF Blue
1961 Ford Consul 848SPH Navy Blue
1965 Morris Oxford CWV695C Navy/White
1972 Hillman Hunter KPG974K Metallic Red
1977 Renault 16 NDR697S White
1980 Talbot Alpine CAM687V Navy Blue
1982 Vauxhall Cavalier VPM495Y Green
1985 Ford Granada C708SPC Maroon Red
1986 Ford Escort D194KCV Grey
1988 Vauxhall Cavalier F413VCV Blue
1990 Mazda 323 F H896FGL Red
1993 Citroen Zantia K628PRL Blue
1997 Renault Megane P396RAF Blue
2002 Renault Clio WL51LUR Metallic Green
6
Our weaknesses
  • AttentionWe are poor at monitoring.
  • There is no such thing as voluntary attention
    sustained for more than a few seconds at a time.
  • Quote from William James (1890)
  • Higher order (cognitive) processes
  • We are not good at some types of decision
    making, for example, deductive reasoning.

7
Deductive reasoning
  • The process of reasoning from one or more
    premises with regard to what is known, and upon
    which a logically specific conclusion can be
    reached.
  • All A are B,
  • All B are C,
  • therefore, all A are C.

8
Inductive reasoning
  • Reasoning from specific facts or observations to
    a general conclusion that may explain the facts,
    that is, it is not possible to reach a logically
    certain conclusion.
  • All men are mortal,
  • therefore, Fred Bloggs is mortal.

9
Deductive versus Inductive reasoning
  • Deductive - logic, while Inductive - particular
    conclusions are drawn from more general
    principles.
  • Inductive reasoning involves an element of
    doubt/uncertainty.
  • If Alan is taller than Bill, and Bill is shorter
    than Chris, is Alan taller than Chris?

10
Common mistakes
  • Draw incorrect conclusions, for example, if I
    take my umbrella, then it will rain.
  • Reverse the propositions in the conditional
    statement, for example, if the plane will be
    diverted, then there is fog.
  • Confirmation bias (seek to confirm).

11
(No Transcript)
12
Wasons 4-card problem
  • You have four cards with a letter on one side
    and a number on the other.
  • E F 4 7
  • If a card has a vowel on one side, it will have
    an even number on the other.
  • Which two cards do you want to turn over to
    check whether this rule is valid or not?

13
Drinking age rule
  • Drinking Drinking 22 years 16
    years
  • a beer a coke of age of
    age
  • Which card or cards do you want to turn over to
    check whether the drinking age rule is valid or
    not?

14
Entering the country
  • Entering In transit Inoculated
    Inoculated
  • against
    against
  • cholera typhoid
  • hepatitis
  • The rule people entering the country have been
    inoculated against cholera.
  • Is this valid or not?

15
Explanations
  • People do not reason logically they simply
    apply their knowledge of the world helps cope
    with uncertainty.
  • Meaningful content limits of working memory.
  • If correct, not an issue,if incorrect, can lead
    to problems.
  • Difficulties representation, negation,
    language.
  • Confirmation bias search for evidence that
    confirms our beliefs.
  • For example, Three Mile Island.

16
Three Mile Island, 1979
17
Decision making
  • Early models based on Normative decision making
  • Break down decision problems.
  • Do this by identifying the alternatives.
  • Weigh the outcomes in terms of their usefulness
    (utility).
  • Select the best outcome.
  • Goal - to seek pleasure and avoid pain.
  • When decision making, we
  • seek to maximise pleasure (ve utility)
  • seek to minimise pain (-ve utility).

18
From Normative to Descriptive
  • In the 1970s, the basic UTs failed, because of
    the subjective element in the observed behaviour
    of decision makers.
  • There was seen a need to take into account human
    irrationality and biases.
  • Hence, the Descriptive models appeared.

19
The Prisoners Dilemma
  • Suppose that two men have been arrested and they
    are charged with a bank robbery. Each man is
    found to have an unregistered firearm at the time
    of the arrest. The police do not have conclusive
    evidence that the two men actually robbed the
    bank, and need a confession from at least one of
    the men in order to make a successful
    prosecution.

20
The Dilemma
  • If neither confesses, they will be charged with
    possessing an illegal firearm and jailed for a
    year.
  • If they both confess, they will each be given an
    intermediate-length term of 10 years.
  • Further, the prisoner who confesses will be let
    off, while the other will get the maximum
    sentence of 20 years.

21
Would you confess?
  • Prisoner A
  • Confess Not Confess
  • Prisoner B
  • Confess Both get A20 years
  • 10 years B0 years
  • Not A0 years Both get
    1 year
  • Confess B20 years

22
Game theory
  • Suggests that much decision making is like
    playing a game with the following features
  • Minimax loss rule - minimise possibility of
    maximum loss (20 years) - confess (possibility of
    0 or 10 years).
  • Maximin gain rule - maximise possibility of
    minimum gain (least favourable outcome 20
    years) - dont confess.
  • Maximax gain rule - maximise possibility of
    maximum gain - confess.

23
Normative and Descriptive
  • Criticism of early (normative and descriptive)
    theories -
  • they often do not use problems and scenarios
    that are realistic.
  • Solution the Prescriptive models.
  • These focus on how people should make decisions
    to conform to the normative model.
  • Still idealised, but taking into account, the
    real situation often characterised by ambiguous
    and incomplete information, limited time
    resources, and high stakes.
  • This led to the development of naturalistic
    decision making (NDM) prescriptive models in the
    1990s.

24
Insights into NDM (complex decision making)
  • Klein (1993) and Rasmussen (1993)
  • Focus on finding a course of action which works.
  • Assess situation and select course of action
    (experience helps - become quicker and more
    accurate).
  • Act without considering all contingencies. Course
    of action is not necessarily the best one - best
    one at that point in time.
  • Choice is related to evaluation and mental
    construction of problem.
  • Focus on relevant options rather than filtering
    out unacceptable ones.

25
Putting the pressure on
  • In a high workload/panic-type situation, what
    happens?
  • Resort to automatic (skilled) behaviour, for
    example, use of checklists will help to reduce
    memory load.
  • High levels of attention can be sustained.
  • Will become tunnel-visioned, for example,
    fixation in terms of problem-solving.

26
Historical perspective - decision making
  • Early decision theories based on (a) humans
    operate in ideal circumstances, and (b) make
    optimal decisions.
  • Recent work - we strive to make the best
    decisions in any given situation.
  • Naturalistic theories are a mixture of different
    models and strategies, and more suited to
    explaining decision making in operational
    environments such as the flight deck,
    fire-fighting/emergency services.

27
How do humans make decisions?
  • 1. Satisficing
  • We do not consider all the options, but opt for
    the first choice that satisfies us, for
    example, working through a long menu.

28
How do humans make decisions?
  • 1. Satisficing
  • We do not consider all the options, but opt for
    the first choice that satisfies us, for
    example, working through a long menu.
  • 2. Heuristics and Biases
  • We do not apply logic but tend to resort to
    feelings
  • For example,
  • All the families having exactly six children in
    a particular city were surveyed. In 72 of the
    families, the exact order of births of boys (B)
    and girls (G) was G B G B B G.
  • What is your estimate of the number of families
    surveyed in which the exact order of births was B
    G B B B B?

29
3. Availability (Anchoring)
  • The extent to which information is available to
    us can determine our decision making.
  • Influence of media and how available information
    is to us. Evidence when there is a health scare,
    for example, about the contraceptive pill.
  • Example
  • What percentage of African countries are in the
    United Nations?

30
3. Availability (Anchoring)
  • The extent to which information is available to
    us can determine our decision making.
  • Influence of media and how available information
    is to us.
  • Odds of dying ...
  • In a car crash 5,000 to 1
  • From surgical complications 80,000 to 1
  • In a plane crash 250,000 to 1
  • By falling out of bed 2 million to 1
  • WINNING THE LOTTERY 80 million to 1

31
4. Overconfidence
  • We tend to overvalue our judgement skills.
  • Example
  • Absinthe is a liqueur or a precious stone.

32
4. Overconfidence
  • We tend to overvalue our judgement skills.
  • Example
  • Absinthe is a liqueur or a precious stone.
  • 5. The Gamblers Fallacy
  • Luck will change, for example, have lost money
    on five horse races, therefore, will win on the
    sixth race.
  • But, probability has no memory

33
4. Overconfidence
  • We tend to overvalue our judgement skills.
  • Example
  • Absinthe is a liqueur or a precious stone.
  • 5. The Gamblers Fallacy
  • Luck will change, for example, have lost money
    on five horse races, therefore, will win on the
    sixth race.
  • But, probability has no memory
  • 6. Fallacy of Composition
  • Parts of the whole make up the whole, for
    example, the horns/halo effect.

34
More evidence of plasticity
  • Order effects
  • How questions affect answers?
  • Q.1. Do you think a Communist country like Russia
    should let American newspaper reporters come in
    and send back to America the news as they see it?
  • Q.2. Do you think the USA should let Communist
    newspaper reporters from their countries come in
    and send back to their papers the news as they
    see it?

35
Results
  • Q.1. Do you think a Communist country like Russia
    should let American newspaper reporters come in
    and send back to America the news as they see it?
  • Q.2. Do you think the USA should let Communist
    newspaper reporters from their countries come in
    and send back to their papers the news as they
    see it?
  • Counterbalanced design - 50 had Q.1 first.
  • Q.1 82 agreed when 1 first, 64 agreed when 2
    first.
  • Q.2 55 agreed when 1 first, 75 agreed when 2
    first.

36
Pseudo-opinions
  • Which of the following statements most closely
    coincides with your opinion of the Metallic
    Metals Act?
  • 1. It would be a good move on the part of the
    USA.
  • 2. It would be a good thing, but should be left
    to individual states.
  • 3. It is all right for foreign countries, but
    should not be required here.
  • 4. It is of no value at all.

37
Results
  • 1. It would be a good move on the part of the
    USA. (15)
  • 2. It would be a good thing, but should be left
    to individual states. (41)
  • 3. It is all right for foreign countries, but
    should not be required here. (11)
  • 4. It is of no value at all. (3)
  • No opinion (30).

38
Inconsistency
  • Principles
  • Public officials should be chosen by majority
    vote.
  • Every citizen should have an equal chance to
    influence government policy.
  • The minority should be free to criticize majority
    decisions.
  • Derived statementIn a city referendum, only
    people who are well informed about the problem
    being voted on should be allowed to vote.

39
Results
  • It was found that
  • 51 agreed with anti-democratic idea that only
    well-informed should vote.
  • Similar study with taxpayers.
  • It was found that
  • 79 agreed that only taxpayers should vote.

40
Problems
  • Integration of information problematic for us
    (attention deficit).
  • Resource limitations (memory) perhaps cannot
    cope with all the aspects involved.
  • Prediction outcomes create uncertainty,
    possibly because of difficulties associated with
    integration.
  • Language, for example, negatives, conditional
    clauses, use of probability poor understanding.
  • Simple manipulations can change our decision
    making, for example, switching the order of
    questions can influence the answers.
  • People when asked will often give answers.
  • Generally, people exhibit inconsistency.

41
Summary Making decisions
  • Construction of a mental representation (story)
    an integration of available information,
    knowledge and personal beliefs about the world.
  • Assessment of the situation.
  • Realistic settings uncertain situations,
    incomplete, and often, contradictory information,
    time pressure, delay in feedback, shifting, and
    competing, goals, and changing conditions.
  • In terms of strategy, experiments at Bristol have
    shown differences in how people perceive levels
    of risk according to how information is
    presented.

42
Conclusions
  • We excel in situations which demand the use of
    inductive reasoning (unlike machines/computers
    that can programmed to carry out deductive
    reasoning).
  • It could be concluded that we do not use
    knowledge optimally - we use short cuts which
    guarantee solutions (which are not necessarily
    the best) the fast but frugal heuristic.
  • In this sense, uncertainty is not a problem,
    because we are not very efficient decision makers
    anyway.

43
Finally
  • Many people would sooner die than think. In
    fact they do.
  • Bertrand Russell
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