W2016 Test 2 Marking Guide

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University of Waterloo *

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162

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Mechanical Engineering

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Jan 9, 2024

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BME 162 Winter 2017 Test 2 Marking Guide

1. (2marks, 1 for the correct term and 1 for the explanation) Most people can understand the sentence below: I hpe yo do wel on your tst toay. Why? • Solution: • Mark 1 - This is explained by top down processing . Mark 2 - The context of the situation is used to determine what the missing letters are. attention: Feature detection is used to identify the characters but is not adequate to determine the words.

2.(2 marks, 1 for the correct term and 1 for the explanation) Your favourite hockey team is the Toronto Maple Leafs but your friend’s favourite team is the Montreal Canadians. Whenever you watch hockey with your friend, he keeps complaining that the game is biased and they don’t call enough penalties on Toronto. To you it seems the other way around; the referees do not call enough penalties on Montreal. Explain what is happening here. • Solution: • Mark 1 - this is explained by selective perception Mark 2 – in selective perception your goals and objectives influence what you perceive ** possible solution (but probably not as good as you are not likely attending to infractions) Mark 1 – this is explained by selective attention Mark 2 – each of you are paying more attention and looking for the infractions of the other team.

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3.(2 marks) A nurse is working on a calculation of a drug infusion. The calculation requires her to use several numbers and make several different calculations. While she is doing this, a colleague comes up to her and says “Can you call Dr. X at x39516?”. Immediately she finds she needs to restart the calculation. She also doesn’t remember the extension of the doctor. What has happened? • Solution: Mark 1 – a mention of resource use(mark 0.5) , in this case numbers and auditory(mark 0.5) are being used. Mark 2 – an explanation that the resource is being used heavily for the calculation so she cannot put enough resources on the phone number to remember it. In her attempt to do this, she loses her memory of her calculation.

4.(2 marks) Anne is sitting in front of the TV doing her homework. Anne has wanted to watch this television show all week but feels she also needs to do her homework. She is working hard on a problem that she found challenging in class. When Anne finishes the problem, she realizes that the television show has ended and she did not see how it ended. Use theories of attention to explain what was happening to Anne? • Solution: Mark 1 – a mention of multiple resource theory Mark 2 – an explanation that the visual and auditory resource pools were taken up by the homework, which was the more challenging problem. • Attention: could also say that it was a case of selective attention, but this should probably receive 1 mark deduction (assuming a good explanation) since it is Anne’s intention to both do her homework and watch the tv show.

5.Name the cognitive bias You are trying to sell a bicycle. You think it is worth $200 but everyone who comes to see it will only offer you $50. _____endowment________________________________ You really want to buy a certain cell phone so you read every good review you can find on that phone and dismiss the bad reviews. __________confirmation bias_____ You continue programming a video game you’ve been working on for months, despite the fact that you’ve just heard that something very similar was just released. ______sunk cost_______________________________ You’ve lived with the same three roommates for the last two years. There are a lot of things you don’t agree on, but you’d rather stay with them than trying to find new roommates. ________status quo or comfort bias______________________ You get into a heated argument with your classmate that your solution on the last assignment is more correct than hers was. Unfortunately when the assignment is returned, your classmate did better on the question than you did. __________overconfidence _______________________

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6.(10 marks) Solve the crossword 1.Wizardofoz 2.Trust 3.chunking 4.Affinity (4) 5.Script (5) 6.Projection (6) 7.Gorilla 8.Persona 9.mapping 10.Stroop (10)

Question 7 Identify 3 biases (1 mark for each correct term) and connect it to the case (1 mark for each connection). Solution Many biases and heuristics would work. Anchoring, cognitive tunnelling, confirmation bias, etc. You could also approach this problem by looking at input related, hypothesis generation related, and action choice related biases. I took 0.5-1 mark off if you state the term incorrectly such as satisficing bias. Satisficing is a cognitive strategy that people use in decision-making but is not a specific bias.

Question 8 Solution • Seniors with low level of tech experience and cognitive difficulties – Novice Users (1 Mark) • Their children) with moderate/high levels of computer and tech experience – Expert Users (1Mark) • Any sensible recommendation would work (1 mark per recommendation) E.g. low memory demands, error reduction techniques, easy to learn NOTE. Some of you have identified both user groups as novice. That is fine as long as you provide your reasoning. Just stating that this app is for seniors and their children is not enough (-1 mark for that).

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Question 9 • Solution – 5 Marks • Overtrust in automation – Jack trusted the automated aid more than its reliability (1 Mark) • Jack is experiencing “automation complacency”, he stopped monitoring the automation over time. (1 Mark) • This automated system is dumb and dutiful. It fills prescriptions and doesn’t check whether it is appropriate (1 Mark) • Levels of Automation • Current level of automation is execution without notification (1 Mark) • A better system is either execute and inform , or confirm before execute (1 Mark)

10.(7 marks) An automated skin cancer detection program has been developed. It works by taking a photograph of the suspected cancer lesion, then uses sophisticated algorithms to determine whether the lesion is likely cancerous. The sensitivity of the test is 83% and the specificity of the test is 62%. If your population has an underlying prevalence of skin cancer of 23 people in 10, 000, if you test 500 people how many people will receive positive test results and how many will receive negative test results? Discuss whether or not this is a good test. • Solution: Calculate how many people in the test population likely have cancer. If 23/10, 000 have cancer, likely x/500 have cancer. X=1. (1 mark) If the sensitivity is 83%, then 83% of the people with cancer are detected. .83x1= .83 (or essentially 1 person). (1 mark) If the specificity is 62%, then .62x499=309 . 309 people without cancer will be properly classified as not having cancer. (1 mark) The number of people with positive results will be 1+(499-309)= 191 (1 mark) The number of people with negative results will be 309 . (1 mark) The test is a good test in that it does not miss many people who have cancer. (low misses in signal detection theory language) but the test is a bad test in that it generates many false positives (false alarms in signal detection theory). (2 marks for 2 points).

11.(4 marks) The company with the skin detection software in the previous question is considering releasing the software to two markets, dermatologists who regularly diagnose skin cancer, and as an online service that patients could access on their own. Use the concepts of human interaction with automation to explain what the effect of the software might be on these two different populations. • Solution: Dermatologists. (1 mark) We would expect this population to be relatively well calibrated to the prevalence of cancer in the population, and should be calibrate fairly well to the reliability of the automation. They should be able to interact with the automation well. (1 mark) Patients. (1 mark) This population is not likely to calibrate as well to the automation so there are likely to be cases of overtrust and undertrust. Either situation could lead to the patients making the wrong medical decision – either not following up appropriately with their doctor, or becoming overly concerned about their situation. (1 mark)

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12. (6 marks) Explain three ways, at three different stages of a human factors design process, that personas could be used effectively and outline how they would be used at these stages. Solution. Stage 1. Early Prototyping: Personas can be used in developing storyboards / Use cases can be created for each persona. Stage 2. User Research: Interviews can be made with the user groups modeled in personas / Task analysis can be conducted for each persona. Stage 3. Testing: User groups can be selected based on personas. / Walkthroughs can be conducted using personas. Other sensible answers were also accepted. You need to show how specifically personas are used at different stages. Weak answers: Personas help identify user needs (Yes, but how?).

13.(3 marks) A cyclist hits a pothole on her bike and falls down. Explain what happened, using the concepts of controls and control order. • Solution: A bicycle is an example of a second order control system (discussed as an example in class). (1 mark). The pothole causes an input to the bicycle that causes it to accelerate (most likely in angular momentum side to side) (1 mark). This is a very difficult problem for a human to control. A bicycle is inherently unstable, which is what makes the pothole so disruptive that the cyclist can regain control. (1 mark).