Psych 494 Midterm

Pheasant did a survey asking why people don't bother with ergonomics. 5 findings

1. I know how to use the product so everyone else will too 2. I made it for average people to understand (but this leaves out half the population) 3. People will adapt to the product 4. Ergonomics is a thing but I would have to hire the person and it would be expensive 5. I'm going to rely on common sense. An ergonomist would tell me things I already know.

6 common themes

1. The Systems Approach: every event has determinants at multiple levels 2. Error: errors are possible to avoid so systems should be made to accommodate errors 3. Design: You have to know how something works in order to know how to use it 4. Consider the User: designers need to consider who is using their product 5. Trade-offs Always Exist: enhancing one feature of a system will change other features. This needs to be balanced 6.Feedback: critical in refining the performance of humans, machines etc.

Fredrick W. Taylor's case study on Bethlehem Steel

Coal company. Men would stand outside the building with their shovels and those who had a shovel were hired for the day. -The company later wanted to find what type of shovel allowed maximum efficiency and hired Taylor. -Once they found the most productive shovel, they provided the shovels to the workers and productivity increased. -This led to the development of time-study methods

Sinclair's study based on the butterfly ballot

Did the same kind of ballot along with a written one and gave it to university students. All students got 100% on both the whole punching and writing out the persons name they wanted. BUT when they went to bonneydoon mall. $ in 53 ballots were mistakenly punched. Which is significant in a real vote.

What is ergonomics? and what are the 3 schools of thought on "human factors" and "ergonomics"?

Ergonomics how things work and how they're used. The study of human work 1. human factors and ergonomics are the same thing 2. Ergonomics is the physical design (like a chair) whereas human factors is more about cognition 3. ergonomics is a subset of human factors

Zimbardo's experiment and what did it lead to?

Experiment #1: He took a car and parked in near an upper class university for a week. No one touched it. Experiment #2: He bought the exact same car and parked it by a lower class university, took the license plate off and put the hood up. Within a day, the car had been stripped over tires, radio etc. Experiment #3: He went back to the upper class university and smashed the windows of the car. This led others to continue vandalizing the car. This led to Broken Windows Theory.

Keizer and Colleagues test of the broken windows theory

Experiment #1: they put junk mail on peoples bike handles by a sign that says no graffiti. 1 in 3 people dropped the flyer on the ground Experiment #2: they again put junk mail on peoples bikes but also vandalized the wall. This led to double the amount of people dropping the flyers on the ground. Experiment #3: they put an develop sticking out of a mailbox with money in it. 13% of people took the envelop. Experiment #4: they did the envelop again but also vandalized the mailbox. This led to twice as many people taking the envelop.

Absolute Threshold

Faintest weakest stimulation that people are still consciously aware of. ????

Broken Windows Theory

Fix the small things in society to avoid the bigger problems. This leads to 2 outcomes: 1. vandalism and petty crime will be deterred 2. major crimes will be prevented.

Understanding User's mental models

Gillian -Measure mental models -best methods -stimuli -procedure -results -conclusions

Example of Weber's law and good vs bad design

Give people weights and ask them if they notice a difference between the weights. OR turn on a TV and put it at 1 bar for volume then change it between 1 and 2 bars. You should notice a different. But then if you put the TV as loud as it can go and change it to one less you won't notice a difference. This is because our human ears need a bigger change when listening to loud things compared to quiet.

After WW2, human factors became a profession around the world. The one that the prof is involved in is?

Human Factors and Ergonomics Society, also changed it's name. -They focus on making advances in technology to make life easier and make the technology easier to use.

What is human factors and Ergonomics?

Human factors discovers and applies information about human behavior, abilities, limitations, and other characteristics to the design of tools, machines, systems for productive, safe and effective human use. -Basically studies how people use things and finds and better and easier way for them to use it. -relates to cognitive engineering (workplace environment)

revenge effect

IRONIC unintended consequences of mechanical, chemical, biological or medical systems. The designer hasn't thought of everything and as a result it prevents people from using it. eg. people will arthritis are given pain relievers but the bottle to open the pain relievers is so hard to open. Which is IRONIC.

Human Factors and Ergonomics is found mostly in what type of workplace?

Industry 39% government 20%

Fitt's Law *KNOW

Intended to measure the information capacity of the human motor system. He wanted to know how much information we could act on. T= log(2) (D/W+1) T=reaction time D=distance of target W=width/size of target

Theory of Affordance *KNOW

J.J.Gibson Stress the importance of stimulus array: is the light rays that have entered your eye which produce the image on your retina.

Situation Awareness (SA

Knowing what's going on around you. What is your situation and how well are you aware of what's happening around you? -main precursor for decision making and performance. -Perception (info) is sent to your brain which helps you figure out what it is and what to do with that information.

Where did the origins of Gibsons theory come from?

Kurt Lewin = "valence" and Koffka Valence: combining power of elements. a mailbox only has valence is you want to mail a letter.

3 stages/ levels of situation awareness

Level 1 SA: perception of elements in the environment. Includes attention because you will not be aware of something if you're not paying attention to it. Level 2 SA: comprehension of the current situation. -encompasses how people combine, interpret, store and retain info. e.g. combining maybe sight and sound. Level 3 SA: projection of future status: determines decisions made and actions performed. What comes next?

Who influenced Ludwig's theory and what did that person invent?

Norbert Wiener who invented the cybernetics theory

Feedback: Fundamental Principles of Interaction

Norman This can be a type of signifier. Feedback allows us to fix our actions. If something didn't work, do it differently next time. eg. taking medication action: take pills action location: pill bottle cue to action: time to take medication problem: can't remember if you already took them or not. They created GlowCap which is a bottle connected to the internet where the lid lights up if you have not taken that medication.

Mapping: Fundamental Principles of Interaction

Norman. You have a desired goal, how do you get that goal? relates desired goal to (apparent) means of accomplishing goal. -based on the concept of stimulus-response compatibility and control-display relationship eg. recording something: there's a rewind, fast forward, stop etc buttons. What do you press to record? Contains 3 things 1. spatial analogies 2. cultural conventions 3. natural mapping

Applying the systems approach at a macroergonomic level

big picture things -task design: transform how tasks and hobs are accomplished -training: change workers behaviour by providing skills and teaching procedures -selecting/ organizational design: recognize individual differences in ability to accomplish work. (who's in charge of what?)

What are the top 3 specific fields in Human Factors and Ergonomics?

computers 22% aerospace 22% industrial processes 17%

Spatial analogies: mapping

e.g. to turn up the volume you might have a slider switch. When you slide it up, you will get more.

Natural Mapping: Mapping

exists if there is similarity of layout, behaviour or meaning. Layout: locations of stovetop controls correspond to the arrangement of burners Behaviour: turning the steering wheel left turns the car left Meaning: emergency stop button is coloured red.

Results of the Clearview Hwy

-nighttime sign reading distance improved 16% at 70km an hour -upper/lower care Clearview letter gave 14% improvement over all CAPS (people are worse at reading all caps) -greater improvement came in older adults.

People with a career in human factors and ergonomics have training in what?

-psychology 36% -engineering 24%

Things they did not consider in Elton Mayo's study

-the productivity may have increased because it was the great depression and these people were grateful they had jobs so they worked harder -because they were constantly changing things it may have been due to uncertainty.

Norman and Natural Design: 6 Fundamental Principles of Interaction

1. Affordance 2. Constraint 3. Signifier 4. Feedback 5. Mapping 6. Designer's Conceptual Model

What causes are attributed to behaviour? Why do people do what they do?

1. Dispositional: action seen as caused by personality (implies it's your personality, something stable within you) 2. situational: action seen as influenced by environment (your subject to your current situation. eg. are there people around you?)

What education do you need to be an ergonomist?

1. Highest designation requires master's degree, 3 years of experience and a written exam. This allows you to become a certified professional ergonomist (CPE), Certified Human Factors Professional (CHFP), Certified User Experience Professional (CUXP). 2. Bachelors degree and 2 years of experience to be a certified Ergonomics Associate (CEA)

Cognitive capacities and mental workload

feeling of mental effort or level of use of human operator's limited resources. -When attentional resources are exceeded, further increases in task demand will reduce performance. -If you get someone to mentally juggle too many things, they won'r be able to do it. This is not our goal, we want people to be at their peak of performance. eg. how much are we forcing pilots to do at once while taking off? Are we making them think of 18 different things or only 4?

The systems approach

focused on arrangement of and relations between the parts which form a whole

Implications for design: Bottom-up

information that catches a person's attention Maximize bottom-up processing: -increase visual legibility -avoid easily confusable stimuli eg. acetazolamide vs. acetohexamide are confusing

Shape coding

intuitive relationship between control shape and function. Changing the shape of things.

Weber's Law

is the difference threshold the same for all standard stimuli? We know a lot about human perceptual abilities, but designers don't always know. k= JND/S k=constant ("Weber fraction") S=stimulus intensity

Research evidence of affordance by Eleanor J. Gibson (Gibsons wife)

visual cliff experiment. Mom would try and get child to walk across the visual cliff. The majority of kids wouldn't. Conclusion: infants already have depth perception. Meaning affordances don't require much learning.

2. requisite memory trap

working memory is limited. There's only a number of things we can remember at once. eg. forgetting you already told an aircraft they can land, and now you have 2 planes that are going to land at the same time.

Elton Mayo

-During the great depression, an electrical company wanted to cut costs of production without firing people. Study #1: the make the room darker to save on electricity Study #2: they studied 6 women changing their work hours, the temperature of the room, lighting etc In both studies they found the level of productivity increased and they wanted to know why. -This led to the Hawthorne effect.

Attribution Theory

-Fundamental Attribution Error -Actor-Observer Discrepancy

example of measuring workload

-Get pilots to drive a plane and drop a bomb at a specific location - THIS IS PRIMARY TASK. -Then get them to do the same task again but this time counting down from 100. SECONDARY MEASURE -Then get them to do it again and get them to say what they're doing. They found this a lot harder then counting down. SECONDARY MEASURE

The 2003 Blackout

-Hot day so lots of people using AC. -there was a software problem at MISO which the operator fixed but forgot to restart the program -There was a mechanical failure at one of the units but the alarm system failed so no now knew. -There was another software fail and no one bothered to tell anyone about it while they fixed it -When it's hot outside power lines start drooping and they were hitting trees so they would turn off, this led to other power lines having to take over for the ones that stopped working. -These other power lines were getting overload and shut off automatically once they reached their max capacity. -One of the most important lines shut down because of this. -biggest blackout in US history where 50 million people in eight states and Canada blacked out. ONLY ALL OF THESE PROBLEMS TOGETHER LED TO THE BLACKOUT. A SINGLE PROBLEM STATED ABOVE WOULD NOT HAVE LED TO THE BLACKOUT.

PARI (Jonassen et al)

-consists of dyad of two experts: one poses problem, the other attempts to solve the problem -at each step, problem solvers draw a diagram to represent their mental model of the state of the system. e.g.. you have a pilot and a flight instructor. It's a dyad (only the two of them). The flight instructor might give the pilot problems and the pilot has to describe what he is going to do about it and why.

Cognitive Task Analysis (CTA) + assumptions

-describes cognitive processes required to perform a task. -models internal representations and mental processing of users Assumptions: -some actions are physical (eg. push button A) -some actions are mental/cognitive operations (eg. decide which button to push). You want to know how they pushed the button (physical) and then why they pushed that button (cognitive).

Frank Bunker Gilbreth & Lillian Gilbreth (Taylor's colleges)

-developed motion studies -They studied the movements that are done to complete a specific task and then find an easier more productive and time consuming way to do so.

What are some benefits of hiring an ergonomist before releasing a product?

-increased product sales -increased user satisfaction -increased user productivity -decreased customer support costs -decreased development costs -decreased employee turnover/ illness -decreased training costs to teach employees how to use the product -decreased maintenance costs

Gibsons 4 affordances of the terrestrial environment (earth)

1. The media: the air - the atmosphere affords breathing, seeing, hearing etc. 2. The substances: solids and liquids. - water affords drinking, washing. vs. solids afford shaping, moulding etc. 3. The surfaces and their layouts. -horizontal, rigid, flat surfaces afford support. Vertical surfaces afford barriers. 4. The objects: may be attached or detached. - a handle affords carrying the object. Objects can have several affordances. SPECIAL TYPE OF OBJECT AFFORDANCE: people. People afford certain behaviours called SOCIAL BEHAVIOUR which is based on the stimuli in the environment. Buildings afford privacy etc..

8 situation awareness "demons"

1. attentional tunnelling: 2. requisite memory trap: 3. workload, anxiety, fatigue, and other stressors 4. data overload 5. misplaced salience 6. Complexity creep 7. errant mental models 8. Out-of-the-loop syndrome

What are the common things you do if you have a job in human factors and ergonomics?

1. communication: write reports, give presentations 2. Management: schedule activities, supervise others 3. System development: determine system requirements, verify system design meets human factors standards 4. research

Basic Principles of the theory of affordance

1. consider perception for the point of view of moving observers (like in real life) 2. consider info in dynamic, not just static image on screen 3. optic array is rich with information, mental processing unnecessary, perception is direct

3 ways to measure mental models - Gillan

1. content-base methods: ask user directly about how she thinks the system works 2. performance- based methods: put user into different situations and se how he reacts, to reveal mental model 3. Indirect methods: ask user to judge similarity (or distance) between several things.

7 stages of action

1. form goal to be achieved (I want the best mark possibly in this course) 2. form intention/ plan action: (I will do well by writing the term paper) 3. specifying action sequence: (first choose a topic, then get articles to read) 4. perform action sequence: (pick topic, get articles, read articles, make a plan, write.) 5. perceive state of the system: (has to be typed 12 pages) 6. interpret state of the system as an outcome (have a reached 12 pages yet or do I have to continue to write?) 7. compare outcome to original goal (it's not good enough, revise draft) STAGE 1: GOALS STAGE 2-4: EXECUTION STAGE 5-7: EVALUATION

How power works: 3 components

1. generation: power plants generate electricity ie. natural gas, combines etc 2. transmission: high-voltage lines carry electricity: carries the electricity to where it needs to go. ie. Power lines 3. Distribution: substations, transformers "step down". Power has to be steeped down to appropriate voltages for the technology using it.

Cognitive Task Analysis typically consists of 3 things.

1. knowledge elicitation: extracting info via in-depth interviews and observations about cognitive events, structures or models. (Trying to get knowledge out of peoples heads.) -Subjects are often subject matter experts: they have high levels of skill and knowledge in the domain studied. 2. analysis of data to develop explanations, extract meaning -a range of quantitative and qualitative analyses are used. 3. knowledge representation: displaying data and relationships, explanations, and meaning derived from analysis. eg. How can you get the relative information on the screen.

Results of attribution theory

1. learned helplessness: if you try to do something and whatever your doing keeps failing, eventually your going to stop doing it. 2. Taught helplessness: the designers causes person to generalize instances of failure to other things. eg. I can't work my laptop, I suck at technology.

Systems Engineering's 4 components

1. requirements: when you're building a building you have requirements (ie. i need this many classrooms). 2. Design, development, production and operation 3. coordination of teams (you aren't going to have a plumber put the windows in 4. automatic control of machinery By having these 4 things it aids in management of complex projects.

User's mental models are constructed by 4 things

1. system image: what information is given, and how is it presented? 2. affordances (and signifiers): what do you think you can do with an object? 3. constraints: inverse of affordances: How does the system restrict your choice of action? 4. Everything else: past experiences, training, instruction: forms of top-down processing.

Measuring workload

1. timeline analysis: measure amount of time spent on task relative to time available; shows how time use changes during course of task. How much can you do given the amount of time? 2. Primary task measure: change nature of main task; record performance changes. You might measure how well a person does on a "primary" task. 3. Secondary task measure: give secondary task; measure performance as primary task changes. LATER, THEY ADDED THESE 4. Subject measures: self-reports of users. Checking how people are after the task. Did they find it hard? stressful? 5. Physiological measures: monitor EEG or use brain imaging to determine physiological correlates of mental work. Monitor brain during the experiment.

Difference Threshold

???

example of the 3 stages of situation awareness

CF-18 Hornet pilot in combat zone. Level 1: aircraft noticed on radar as well as a surface missile Level 2: they recognize the aircraft to be the enemy and that it is slower then their aircraft. but the missile can not be identified. Level 3: pilot predicts that lighting afterburners will allow him to outrun the enemy aircraft; since they can't decide what kind of missile it is, they drop both chaff and flares. -Then the pilot performs the actions necessary to carry out his plan.

B-17 controls in WW2

Chapanis. -The pilots hit the button for the landing gear instead of for the flaps so when they went to land they put up the wheels thinking they put away the flaps which led to a crash. -This is not due entirely to human error but to the design of the plane. -They had the two buttons side by side and they looked the same -Chapanis came in and modified the switches by making one round and putting a flap on the other. This made it easier to differentiate the two.

Application of psychophysics: Highway signs

ClearviewHwy: spent 10 years developing highway sign letters that were more accurate then the current ones. -The old signs, when the highbeams hit the letters they would have too much reflection and it would be hard to see.

Signifiers: Fundamental Principles of Interaction

Norman. -Indicators that communicate appropriate behaviour. eg. opening doors action: push, pull, slide action location: door moves left, right, in, out cue to action: is there a door handle? meaning I pull? problem: doors can be poorly designed and therefore don't reveal signifiers. e.g. salt and pepper: how do you know which one is which? Make them see through. If affordance can not be perceived, a signifier may signal its presence. eg. if there's a block in front of a set of stairs, that's signifying you can't use those stairs.

Affordance: Fundamental Principle of Interaction

Norman. -It's the relationship between a physical object and a given person. -defines what actions are possible. -If things are poorly designed, they should tell us what to do. eg. when you get to a door, a handle is naturally suppose to be pulled.

Constraints: Fundamental Principles of Interaction

Norman. -Opposite of affordance. -Restriction on your choice of actions to a limited subset which contains the correct one, thus reducing error. You want to limit your choices because it narrows down your options of what the right action is. eg. scissors force you to put your thumb in the smaller whole and your fingers in the bigger one leading you to use to scissors properly.

Study of TiVo

ONE OF THE BEST CASES OF DESIGN TV was accessible through the remote instead of pushing buttons on the actual TV. It also gives feedback to tell you if you did something right or wrong. -It records shows based on your likings. THere's a thumbs up or down to tell TiVo if you liked the show it recorded or not. -They tested it on everyday people that didn't have knowledge of how the thing worked. -most of it's features have been ripped off by other companies. If you see a remote similar to the one of the screen, that company took it from TiVo. MOST PEOPLE LOVE THEIR TIVO.

What does each letter of PARI represent?

P= precursor: why are you taking this action? How does this relate to acquiring the info you need or goals you're attempting to reach? -Before you do an action, take a step back. What's your goal, what's relevant, what's not? A= action: what would your first action be in solving this problem? What steps are you required before performing the action? -Break it down. what are your the steps you should follow? R= result: what does the info or feedback tell you about your actions? -Feedback. Did your action work? How does that relate to your goal? I= interpretation: based on your results, what conclusions are you drawing? What needs to be done next? -Did you reach your goal? If not, you have to start over at p.

Fundamental attribution error (aka. person bias or correspondence bias)

Part of attribution theory. -in judgement of other people's actions, people tend to 1. overestimate contribution of dispositional factors & 2. underestimate effect of the situation.

Fredrick W. Taylor

Principles of scientific management 1. apply scientific method to determine more efficient ways to do work 2. scientifically select, and train workers based on their ability 3. monitor the performance and cooperation of workers to ensure that scientific methods are applied 4. locate workers and managers to where they are best suited.

Pros and Cons to broken window theory

Pros: 1. environment is likely contribution to crime. eg. if you have a lot of trees by a bus stop, it is more likely someone is hiding behind the trees making people an easy target. 2. In New York, the president got people to clean up the streets, this is possibly a factor leading to less crime. Cons 1. many other factors contribute to criminal behaviour 2. evidence is equivocal/confounded.

Pros and Cons to PARI

Pros: directed at describing (and relating) cognitions and actions Cons: requires good verbal skills on subject's part

Real affordances vs. perceived affordances

Real: what are the actions you can actually do? received: what are the actions you think you can do?

Norman: Principles of Design for Understandability and Usability.

Sometimes things are made that give off the impression it's used a certain way when in reality it's used a different way. For this reason he suggests designers should use PERCEIVED AFFORDANCES -He brings up the concept of natural design

Case Study: The Butterfly Ballot

The butterfly ballot is a 2 page ballot and you punch a whole i the vote you want. Why was this a poor design?: it was confusing that there was 2 pages, the words were far away from the punch whole, some people couldn't even punch the whole because of arthritis etc.

Designer's conceptual model: Fundamental Principles of Interaction *KNOW

The structure and functions of a system, and how they are interrelated. eg. it's cold in your house so you turn the heat on. It won't heat up faster if you turn it up to 25 vs. 20. That just means the furnace will stay on longer. Design Model: System designer has a concept model representing knowledge of how a system is designed and functions. System Imaging: provides information to user (how to use the product) mental modal: represents the users belief about the system. Ideally you want the designer's concept to by the same as the user's belief although this is not always the case.

Frank and Lillian Gilbreth described 18 kinds of elemental motions called?? *KNOW

Therbligs - almost Gilbreths spelt backwards

Research method of the Clearview Hwy

Took a range of aged people and put them in the passengers seat and tested when they could see the sign and how well. experimental design: test of recognition (looking at street names); recognition distances are up to twice as much as legibility distances. Recognition procedure: particular word appeared on a panel with two other words, reaction time was measured Legibility procedure: read a sign from moving vehicle on test track, record maximum distance for identification

Errors in perceiving affordances

Warren says we are perfect judges of what we see. Gibson comes and says people make mistakes so we can't be 100% correct eg. if there's a lake that partially freezes and then it snows, you might tell yourself it's frozen and go walk over the lake and immediately fall in.

Cultural conventions: mapping

Why do clocks move clockwise? because they made them based on sun dials (the knowledge they knew back in the day).

Cybernetics Theory

a theory of the communication and control of regulatory FEEDBACK. If you get poor feedback, you will change the way you did that thing to try and get a better outcome.

implications for design: top-down

maximize top-down processing in information-poor environments. certain goals help determine which elements to pay attention to. Do you watch the truck coming up behind you on an icy day or do you watch if the light turned green? 1. reduce confusions/maximize discriminating features. eg. acetaZOLAMIDE vs. acetaHEXAMIDE 2. use a smaller vocabulary: improves guess rate under degraded conditions, and encourages highly discriminable word choices. e.g.. for 29,000ft say "flight level two nine zero" 3. create context: eg. "your fuel is low" is more effective then saying "fuel low" 4. exploit context: e.g.. using the phonetic alphabet. alpha, beta etc. 5. ***Test stimuli in the real world e.g.. ClearviewHwy experiment 6. be ware of potential perceptual errors. eg. when you're coming up to a runway that is just off of water or in a dessert, pilots find it hard to know their altitude and exactly where the runway is

Actor- observer discrepancy (aka. situation bias)

part of attribution theory. in judgements of one's own actions, people tend to 1. underestimate disposition & 2. overestimate the situation

Hawthorne effect *KNOW

people work faster and harder when they know someone is watching them.

Application of Fitts's law: Computers with pointing systems

poor design: menus that are not on the edge of the screen take longer to correctly activate. (By reducing the size and place of the target, it's harder to hit and takes longer) good design: menus that are at the extreme edges of a screen such as on microsoft. OR when you click a button that gives you lots of options, they all come up as a circle around the mouse so it's easy to move to and close proximity to the mouse. EVEN better design: you don't need to click anything. You shake the mouse and it means go back or using your fingers to zoom in and out.

Ergonomics

practice of designing products, systems, or processes to take proper account of the interaction between them and the people who use them.

Pros and cons to the 7 stages of action

pros: -separates cognition and action -can aid design (where is user having difficulty) cons: -has discrete serial stages (once you finish one thing, you move to the next. Your life is only writing the paper)- but people have so many other things going on in their lives. -neglect that fact that people get tired -individual differences/ expertise is not taken into account -good for understanding simple tasks, not complex tasks in complex systems.

General System(s) Theory - Ludwig von Bertalanffy

reacted against reductionism (taking organisms that are hard to understand and breaking them into tinny pieces to see the little details) Ludwig says when you do this, you fail to see the big picture such as where the organism lives etc.

Canadarm

read the readings for chapter 3.

Affordance

real(or perceived) set of actions that a specific object or environmental situation makes available to the perceiver. What you do with an object defines the object. -what the object affords depends on the person using it eg. cups-drinking

The tipping point: Morton Grdzins

referring to white flight. After WW2, black people started moving int to white neighbourhoods and white people would move out of the neighbourhoods as a result.

System Engineering: Holistic in nature

requires consideration of all system components, everything that interacts with the system, as well as the environment in which the system operates. i.e. we need doors, windows, computer plug-ins etc

Research evidence of affordance: Warren

stair climbing. They would show people images of stairs and ask them how hard it would be to climb the stairs based on how steep they were etc. Then they did physical studies measuring the people body lengths and then got them to walk up each set of stairs. They found the length of the peoples legs were the most important factor to how difficult it would be to climb the stairs. Conclusion: they found that most people were very accurate in saying whether it would be hard or easy for them to climb the stairs.

Experiment of who to determine a mental model:

stimuli: 13 universities across 12 US cities. procedure : - content method: draw location of items on map & label OR - indirect method: rate distance between items on 6-point scale (10 if the buildings are far apart) -participants took part in 2 sessions and data was then collected Results: those that drew where all the buildings were in both test 1 and test 2 did the best with a 92% accuracy between both. Those who did rate-rate for both tests did second best... etc. Conclusion: -drawing was more reliable than rating -for a mental model to produce a response, it apparently goes through a transformation -different transformations applied for different actions (drawing vs. rating)

Fitts's experiment

the time to acquire (move to) a target is a function of the distance to and size of the target. Touch one metal strip then go across and touch the other. They wanted accuracy more thens speed and wanted to know how fast they could get from one strip the the other. He manipulated variables by making strips farther apart or closer apart.

Applying the systems approach at a micro level

things that you can touch. -environment: adjusting features of the work environment such as temperature, lighting, sound etc. -equipment: modify physical design of tools -interface: alter means of interaction with equipments

1. attention tunnelling

under stress, attention becomes focused on a single stimulus (the amount of things you can pay attention to is narrowed). eg. there was a flight that was landing and they dropped there wheels, one light didn't come on indicating that the wheels didn't lower, so they opened the hatch to see if the tires lowered, meanwhile not paying attention to their altitude leading them to crash.

Implications for design : automaticy and unitization

unitization: things fall into unity. eg. You're getting someones phone and they say (780), we have clustered that into one. automaticy: when a persons behaviours and reactions become somewhat automatic. you can do something without conscious thought. It's easy to do. eg. having words rather than abbreviations etc.

Time-study methods

using a stopwatch to record the time taken to accomplish a task. Someone would stand behind the worker and time them to see how fast they could perform a task. -This was later banned.