Instructor: Vincent Duffy, Ph.D.Instructor: Vincent Duffy, Ph.D.

Associate Professor of IE Associate Professor of IE

Lecture 6 – Decision Making & UncertaintyLecture 6 – Decision Making & Uncertainty

Thurs. Feb. 1, 2007Thurs. Feb. 1, 2007

IE 486 Work Analysis & Design IIIE 486 Work Analysis & Design II

An introduction to human decision makingAn introduction to human decision making

First review end of cognition (lecture 5) and First review end of cognition (lecture 5) and relationship to decision making (lecture 6)relationship to decision making (lecture 6)

Re-introduce QOTD as part of lecture todayRe-introduce QOTD as part of lecture today

Then briefly discuss plan for tomorrow in lab Then briefly discuss plan for tomorrow in lab

6. Long term memory6. Long term memory

Design implicationsThe user is unlikely to develop the same level

of detail (recall) in the use of a product compared to the designer

Therefore, when possible, it is a good idea to:Encourage frequent use of information –

Take advantage of frequency and recency then over time, the task may become more automatic

Standardize and use memory aidsEg. Give list of instructions for sending fax

Carefully design information to be remembered

Make it meaningful and avoid the use of technical jargon when possible

7. Attention and mental resources7. Attention and mental resources

If we devote cognitive resources to one activity, others are likely to sufferEg. Study of the use of cell phones and

driving suggests that accidents are 5x more likely

The rate is roughly equivalent to driving drunk Consider multiple resources

Eg. One can not read a book and watch tv at the same time.

However, one can listen to the spoken version of the book while watching tv.

Visual and auditory processing requires separate resources.

8. Conclusions8. Conclusions

Some general design implications Consider: issues related to

Divided attention, controlled vs. automatic processing & multiple resources

Make the input mode ‘dissimilar’ when possible eg. Take advantage of different pools of resources.

Automation (or more automatic processing of information) allows better time-sharing of mental resources.

Convey Priority - Let the user know the importance of each task to better allocate (mental) resources.

Overview of human decision makingOverview of human decision making

1. Overview of human decision making 1. Overview of human decision making

2. An example: anesthesiology team in hospital2. An example: anesthesiology team in hospital

3. What is the problem with heuristics for 3. What is the problem with heuristics for decision making? decision making?

4. Naturalistic decision making 4. Naturalistic decision making

5. Skill rule and knowledge based task 5. Skill rule and knowledge based task performanceperformance

6. Improving human decision making6. Improving human decision making

IE 486 - Lecture 6 - QOTDIE 486 - Lecture 6 - QOTD

QOTD 1. What are ‘heuristics’?QOTD 1. What are ‘heuristics’?

QOTD 2. How can we model task QOTD 2. How can we model task performance considering the cognitive performance considering the cognitive aspects of tasks?aspects of tasks?

QOTD 3. What are some ways to improve QOTD 3. What are some ways to improve human decision making through human human decision making through human factors engineering design?factors engineering design?

1. Overview of human decision making1. Overview of human decision making

According to Wickens (ch.7)According to Wickens (ch.7)

Decisions are made either Decisions are made either – intuitively - quick and relatively automatic orintuitively - quick and relatively automatic or

– analytically - slow, deliberate and controlledanalytically - slow, deliberate and controlled

1. Overview of human decision making1. Overview of human decision making

QOTD 1. What are ‘heuristics’?QOTD 1. What are ‘heuristics’?– Simplifications in decision makingSimplifications in decision making

– do not always guarantee best solution due to biases or do not always guarantee best solution due to biases or misperceptionsmisperceptions

– eg. ‘satisficing’ (Simon, a psychologist 1957)eg. ‘satisficing’ (Simon, a psychologist 1957)

– suggests a decision maker generates alternatives until an suggests a decision maker generates alternatives until an ‘acceptable’ (not necessarily optimal) solution is found‘acceptable’ (not necessarily optimal) solution is found

it is believed that many people will judge that ‘going beyond this to it is believed that many people will judge that ‘going beyond this to identify something better has ‘too little advantage to make it worth identify something better has ‘too little advantage to make it worth the effort’.the effort’.

Why?Why?– People have limited cognitive capacity and limited timePeople have limited cognitive capacity and limited time

1. Overview of human decision making1. Overview of human decision making

How do economists believe we make decisions?How do economists believe we make decisions?– Rational decision making - it is expected that the Rational decision making - it is expected that the

decision maker will find the ‘optimal’ solutiondecision maker will find the ‘optimal’ solution

– ……based on our concept of what is useful (utility) and based on our concept of what is useful (utility) and willingness to accept riskwillingness to accept risk

2. An example: anesthesiology team in 2. An example: anesthesiology team in hospitalhospital

5 medical procedures are to be performed 5 medical procedures are to be performed urgently on 5 different patients in two different urgently on 5 different patients in two different buildingsbuildings– there are only 3 anesthesiologists plus the ‘one in there are only 3 anesthesiologists plus the ‘one in

charge’ who is supposed to be ‘available’ in case of charge’ who is supposed to be ‘available’ in case of incoming unexpected ‘emergency’incoming unexpected ‘emergency’

– classical or ‘normative’ decision making theory classical or ‘normative’ decision making theory suggests there are different alternatives with different suggests there are different alternatives with different likelihood of outcome …and each has an expected likelihood of outcome …and each has an expected ‘utility’ (good/bad payoff)‘utility’ (good/bad payoff)

2. anesthesiology team in hospital2. anesthesiology team in hospital

4 possible alternatives4 possible alternatives– the ‘one in charge’ begins a procedure and no the ‘one in charge’ begins a procedure and no

emergency occursemergency occurs– or the ‘one in charge’ begins a procedure and an or the ‘one in charge’ begins a procedure and an

emergency occursemergency occurs– or she doesn’t begin a procedure and an emergency or she doesn’t begin a procedure and an emergency

comes in comes in – or she doesn’t begin a procedure and an emergency or she doesn’t begin a procedure and an emergency

doesn’t come in doesn’t come in – see p. 160 for expected outcomes based on likelihood see p. 160 for expected outcomes based on likelihood

and utility/payoffs and utility/payoffs

3. What is the problem with heuristics for 3. What is the problem with heuristics for decision making?decision making?

The decisions are subject to biasesThe decisions are subject to biases– 1. A limited number of hypotheses is generated1. A limited number of hypotheses is generated– 2. ‘memory’ research suggests people will recall what 2. ‘memory’ research suggests people will recall what

was most ‘frequently’ or most ‘recently’ considered - was most ‘frequently’ or most ‘recently’ considered - most readily available.most readily available.

– 3. Certain cues may lead to a conclusion - then not 3. Certain cues may lead to a conclusion - then not enough is then done to eliminate other possibilitiesenough is then done to eliminate other possibilities

– 4. Overconfidence - people tend to believe they are 4. Overconfidence - people tend to believe they are right more often than they really areright more often than they really are

– 5. Cognitive fixation - people tend to ignore cues that 5. Cognitive fixation - people tend to ignore cues that are contrary to their original beliefare contrary to their original belief

4. Naturalistic decision making4. Naturalistic decision making

Decisions in ‘the field’Decisions in ‘the field’– these ideas are considered outside the ‘experimental’ these ideas are considered outside the ‘experimental’

worldworld

It is suggested by some that this is more useful It is suggested by some that this is more useful that ‘experimental studies done in labs’.that ‘experimental studies done in labs’.However, Wickens suggests that these are However, Wickens suggests that these are complementary to experimental evidencecomplementary to experimental evidence– For ill structured problems For ill structured problems – under time constraints and time stressunder time constraints and time stress– high risk and multiple people involvedhigh risk and multiple people involved

5. Skill, rule and knowledge based task 5. Skill, rule and knowledge based task performanceperformance

QOTD 2QOTD 2Q. How can we model task performance considering the cognitive Q. How can we model task performance considering the cognitive

aspects of tasks?aspects of tasks?Rasmussen suggests 3 levels of ‘cognitive’ control and that people Rasmussen suggests 3 levels of ‘cognitive’ control and that people operate at one of the levels depending on the nature of the task and operate at one of the levels depending on the nature of the task and their ‘experience’their ‘experience’

– skill based - reacting to perceptual elements in an skill based - reacting to perceptual elements in an automatic, subconscious levelautomatic, subconscious level

– rule based - rely on if-then associations between cues rule based - rely on if-then associations between cues and actions and actions

typical of those with familiarity but not extensive experiencetypical of those with familiarity but not extensive experience

– knowledge based- when the situation is novel and knowledge based- when the situation is novel and there is no rule or previous experience to draw onthere is no rule or previous experience to draw on

6. Improving human decision making6. Improving human decision making

QOTD 3QOTD 3Q. What are some ways to improve human decision Q. What are some ways to improve human decision making through human factors engineering design.making through human factors engineering design.Eg. Parachutist has a chute that fails to open properlyEg. Parachutist has a chute that fails to open properly– after trying to untangle the cords, they deploy the reserve chute after trying to untangle the cords, they deploy the reserve chute

too late - at 200 ft. too late - at 200 ft.

To reduce chance of an accidentTo reduce chance of an accident– a redesign could have helped recognition of the trouble and a redesign could have helped recognition of the trouble and

awareness of the critical ‘time’ issue awareness of the critical ‘time’ issue

different colors for cloth and cords could have helped different colors for cloth and cords could have helped diagnosis and diagnosis and an altitude sensor (with auditory alarm) could have given an altitude sensor (with auditory alarm) could have given awareness about time running outawareness about time running out

6. Improving human decision making6. Improving human decision making

in complex environments can be helped by trainingin complex environments can be helped by training– using computer supportusing computer support

– to teach pattern recognitionto teach pattern recognition

– break the process into different cognitive stepsbreak the process into different cognitive steps

‘‘People overrely on rapid, intuitive decisions rather than People overrely on rapid, intuitive decisions rather than perform the more difficult analyses’ (Pierce, 1996)perform the more difficult analyses’ (Pierce, 1996)– This suggests that decision aids can support decision making if This suggests that decision aids can support decision making if

they can help ‘counteract’ this tendency to take ‘shortcuts’ (or they can help ‘counteract’ this tendency to take ‘shortcuts’ (or satisficing) tendencysatisficing) tendency

especially when the decision is important, and when there is enough especially when the decision is important, and when there is enough time to do the analysistime to do the analysis

Tomorrow in labTomorrow in lab

Review lab 1, part 1Review lab 1, part 1

Turn in reportsTurn in reports

Demonstrate quantitative aspects related Demonstrate quantitative aspects related to decision making & uncertainty (tutorial)to decision making & uncertainty (tutorial)

Introduce Lab 2Introduce Lab 2