How do people make decisions?
What is the decision making complex made up from?
People have little awareness of how they make decisions
Mental representations are made up from conscious and unconscious processes
How does the brain judge what information it should attend to?
The brain has limited capacity for conscious attention
It makes unconscious judgements about what to attend to
What focuses attention of the brain?
Attention is focused through external and internal cues
e.g. other people, experience, sensation, value
How do people choose what to pay attention to?
People have very little insight into what influences attention
What is significant about whether someone believes they have made a good choice?
How they think they made the decision bears no relation to how the decision was actually made
What are multi-attribute decisions?
What types of decision tend to be made this way?
There are many factors which influence the final decision
Many health decisions are made this way
How does whether the outcome of a decision is ‘good’ relate to how well the decision was made?
If the outcome of a decision is good, this does not mean the decision was made well
A decision may be made well, even if the outcome is not what was wanted
How are goals achieved?
To achieve goals, we make decisions and act
What is a decision?
It is a choice of action between options
Why is decision making a complex process?
It involves many attributes including:
What are the 2 possible decision outcomes?
- satisfactory (good/happy)
2. unsatisfactory (bad/regret)
What are the 3 different types of decision?
What is a certain decision?
There is no risk and a guarantee of an outcome
What is an uncertain decision?
There is a chance that you may or may not get the outcome
The risk is unknown
What is a risky decision?
There is a chance that you may or may not get the outcome
The risk is known
What is the Expected Utility Theory (EUT)?
What is it based on?
It links choice with values and the probability of each option happening
It is based on mathematic axioms/rules of logic
Why is the EUT described as a ‘normative theory’?
A normative theory describes how people SHOULD make decisions
What is meant by expectations and utility in the EUT?
Expectations are the risks
Utility describes the values
What equation is used to calculate the expected utility of an option?
EU = [ p(i) - u(i) ] / i
i = all the expected outcomes of an option
p(i) = probability of the ith outcome
u(i) = utility (non-money value) of the ith outcome
p(i) - u(i) = product of the probabilty x utility of the ith outcome
EU = expected utility
What is the maximum expected utility choice?
A choice based on evaluating the expected utility of all the options
You choose the option with the greatest/maximum value for EU
What is the equation for maximum expected utility?
MEU = EU of a - EU of b
What is significant about the MEU choice?
The MEU option is the ‘correct’ or ‘rational’ choice
Why are decision trees sometimes used in clinical circumstances?
For some people, visually seeing the decision helps them to make it
What is meant by a ‘lumped decision’?
Two factors which are closely linked
e.g. choose to have a diagnostic test for Down’s syndrome
choose whether to continue with the pregnancy or not
What is the problem with the Expected Utility Theory?
People do not always make decisions rationally
What assumptions are made for rational decision making?
- people are motivated to follow rules or axioms
- people have complete knowledge of all options
- people’s representations of options, risk and benefits are accurate
- people know what their values are
- people’s values are stable
Realistically, how do people tend to make decisions?
Sometimes they think hard about a decision, but sometimes it is a gut reaction
Decisions are made in different ways and sometimes they don’t know why they made a choice
What is meant by ‘Bounded Rationality’?
People do not have the processing capacity to calculate EUT
They use simpler, less effortful strategies
What are the 3 less effortful strategies in bounded rationality?
- satisficing (Simon)
- elimination by aspects (Tversky)
- Heuristic (Chaiken)
What is involved in the satisficing strategy?
Choosing a satisfactory criterion and the first matching option
e.g. need 5 rooms, choose 1st house with 5 rooms
What is involved in the elimination by aspects strategy?
Choosing an attribute, and making ‘trade-offs’
e.g. comparing all houses with 5 rooms
What is involved in the heuristic strategy?
using ‘rule of thumb’ and not option/attribute facts
e.g. friend’s advice
What is ‘System 1’ as an information processing strategy?
This is an intuitive-experience strategy and it is fast
What type of information is focused on when using System 1?
You attend to a small part of the decision problem
This depends on the context of the decision problem
How is a choice made when using System 1?
What type of strategy is this?
The choice is made on a rule of thumb triggered by a ‘bit’ of information
This is heuristic
How are decisions using System 1 informed?
They are informed by experience or beliefs
e.g. trusting someone who gave advice
What kind of effort and emotion is involved in System 1?
It is sub-conscious and quick
It involves very little effort or emotion
What is the usual outcome of a System 1 decision?
You are more likely to regret or make the ‘wrong’ choice
What is ‘System 2’ as an information processing strategy?
It is a deliberative-analytic strategy and is slow
What type of information is attended to when using system 2?
All of the details of the decision problem are attended to
What forms a major part of the decision making process in System 2?
Evaluating the pros and cons of all options
How is the final decision made using System 2?
The choice is made based on trade-offs between evaluations of the risks and outcomes
What is the usual outcome of a System 2 decision?
People are happier with the choice made and less likely to regret it
It results in more stable values
What are the emotions involved in making a System 2 decision?
It is conscious, time-consuming and emotionally demanding
How are biases in decision making presented?
The way in which facts are presented biases how a decision is made
How does context lead to biases and affect decision making?
Context ‘leaks information; and provides cues-to-action
People pick up on cues, and this impacts decision representation and judgement
What are the two ways in which cues can impact decision representation and judgement?
- framing (direct)
- perceptions of risk and values (indirect)
Judgements are always changing and are not stable
If people are given the options to:
take part in a trial (opt-in)
opt out of a trial (opt-out)
the standard treatment of take part in the trial (choice)
How many people will choose the trial?
Opt-in: 45% opt to have trial
Opt-out: 61% opt to have trial
Choice: 38% opt to have trial
Based on the trial example, what is this an example of?
What does it show?
It is a nudge
The way in which information is presented influences the way in which decisions are made
How do people give meaning to risk?
What do perceptions of risk influence?
People are ‘hardwired’ to use context to give meaning to risk
Perceptions of risk influence choice, not actual figures
If humans saw a fair coin being tossed:
H H H H H
What would they bet to be the next outcome?
Even though the probability of H or T is the same
Humans like to see patterns in things, so will think the outcome of H is more likely
What is the anchoring hypothesis relating to risk?
Decisions are not influenced by the risk figure presented, it depends on the information surrounding it
What is meant by ‘availability’ in decision making?
Perceptions may be influenced by media, which may not be accurate
e.g. people think tornedoes are more likely to kill than asthma, but this is not true
How do people make informed/reasoned decisions?
What are the 3 steps?
- looking at the disadvantages and advantages of all options and consequences
- evaluating options with their own values
- trade-off their evaluations to make a choice and act on it
What are patient decision aids and what are they used for?
They present information in a fair, balanced way to help patients make informed decisions well
e.g. leaflets, decision guidance
What is the main reason why decision making goes wrong?
Information is missed in our search as we are over-confident after a limited search of information
What other 2 reasons mean that decision making goes wrong?
- our judgements or inferences are biased
2. we think too much and find counter-evidence that does not add more to the decision representation
What are the three types of errors in diagnosis, described by Graber et al?
- No fault
What are examples of ‘no fault’ errors in diagnosis?
- silent disease/not known
2. poor quality data from the patient, e.g. did not talk about all the symptoms
What are examples of ‘system’ errors in diagnosis?
- culture left too long
- patient missed an appointment
- delays in x-rays
- unsupervised junior doctor
How can system errors be fixed?
By identifying weaknesses in the system and making sure it doesn’t happen again
What are examples of ‘cognitive’ errors in diagnosis?
- misdiagnosis from poor data collection
- flawed reasoning
- incompetent knowledge
The doctor’s errors due to being human
What are ways to minimise cognitive errors?
- asking questions and gathering evidence
- looking at pattern recognition
- decision making
- integration of prior clinical expertise
- judgement and evaluation
What was the name of Croskerry’s model?
The Dual Process Model of Diagnostic Reasoning