Chapter 7 Human Computer Interaction “Many tasks we use computers for take less time without.” (Landauer 1995) Copyright (c) 2025 P. Neumann, BSc, MSc, LicEng, PhD, LEL, Eur.Erg – this teaching material is not for resale or commercial use. Note that attribution errors and missing acknowledgements may exist in this material; forHelander which the author apologises 2006 Land Acknowledgement Toronto is in the 'Dish With One Spoon Territory’. The Dish With One Spoon is a treaty between the Anishinaabe, Mississaugas and Haudenosaunee that bound them to share the territory and protect the land. Subsequent Indigenous Nations and peoples, Europeans and all newcomers have been invited into this treaty in the spirit of peace, friendship and respect. Human Variation F 8.2 Median Helander 2006 bizarrebytes.com (Sanders & McCormick 1993) Inclusive design = Better design Product Experience The impact of age How many people have less than “Full ability”? Source: 1996/97 Disability follow-up survey Design Change Cost Miles & Swift 1998 Human Capability Varies REMEMBER! FIGURE 1.1 Analysis of the human-machine interface requires interdisciplinary knowledge of biomechanics, cognitive psychology, and systems design methodology. Helander 2006 HF design – front loaded costs, back-end savings Chapter 7 Human Computer Interaction Usability • ISO definition 1995: “Usability is the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.” • Fun? Why not? • User experience is not decomposed • Do not confuse with functionality! Helander 2006 Good Design? Can I use it? www.geek.com/wp-content/uploads/2015/10/magic_mouse_2_charging-590x330.jpg Human-Design Interaction • More than just “usability” • What experience does the user have? – Frustration – Sense of accomplishment (self efficacy) – Satisfaction – Fun / Joy – Alienation, embarrassment – Injury & Death +++ Human-Design Interaction • More than just “usability” • What experience do users have? • What is “USABILITY” ? • Qualitative or Quantitative? trhicks.com What Does Usability Measure? - the quality of a user's experience when interacting with a product or system - Usability is not a single, one-dimensional property of a user interface. Usability is a combination of factors including: Ease of learning - How fast can a user who has never seen the user interface before learn it sufficiently well to accomplish basic tasks? Efficiency of use - How fast can experienced users accomplish tasks? Memorability – How well can a user remember to use the system (without re-learning)? Error frequency and severity - How often do users make errors while using the system, how serious are these errors, and how do users recover from these errors? Subjective satisfaction - How much does the user like using the system? www.usability.gov Cost Effectiveness of Usability Why is usability testing so cost effective? Helander 2006 (Sanders & McCormick 1993) Cost Effectiveness of Usability Contributions: • • • • • • • • • • • • Better look and feel to interface Increased customer satisfaction Less documentation needed Decreased help desk costs Decreased training time Includes user requirements Decreased development time and costs Decreased maintenance costs Increased work process control Increased sales and revenue Post release changes too expensive 10 times return on usability design efforts Helander 2006 Cost Effectiveness of Usability uservision.co.uk USABILITY METHODS See also: www.usability.gov Usability Testing When? • Testing in Software Lifecycle – Start early and test repeatedly HOW? • Early: Formative Evaluation – To influence design • Late: Summative Evaluation HOW? – To evaluate effectiveness of interface (Sophie Quigley , 2009) Usability Testing What? • Early: Formative Evaluation – Design documents – Paper prototypes – Early prototypes • Late: Summative Evaluation – Alpha and Beta versions – Finished product • GET QUALITATIVE AND QUANTIATIVE INFO (Sophie Quigley , 2009) Usability Testing Who? • Users – Target users – Representative subjects • Experimenters – Developers – Usability professionals (Sophie Quigley , 2009) Usability Testing Where? • Field – More realistic environment • Usability Lab – Fewer distractions – More scientific measurements (Sophie Quigley , 2009) Usability Testing How? • Representative Tasks • Protocols – Think aloud – Co-discovery • Measurements – Rate of learning – Efficiency – Effectiveness • Discussions (Sophie Quigley , 2009) DESIGN PRINCIPLES? • List 5 design principles that would support good product usability… Design Principles (heuristics) 1. Do not violate users expectations (mental models) 2. Increase Consistency 3. Decrease Memory Requirements 4. Increase Feedback 5. Consider Individual Differences 6. Direct Manipulation >>> Helander 2006 Point of Sale Machines… Principle 1. Don’t Violate Users’ Expectations • Need to understand how user thinks • Don’t let code structure dictate • See tips – Table 7.1 Helander 2006 Principle 2. Consistency • Can be a major problem • Abbreviations: – Four main strategies – Be consistent (check: fig 7.2) • Location of info Helander 2006 Principle 3. Decrease Memory Requirements • STM = 7 +/- 2 chunks • Limit menu length • Chunk Info e.g. Figure 2.3 Helander 2006 F.2.3 Chunking Information • Recognition time decreased by 40% w new layout. Helander 2006 Principle 4. Increase Feedback • Give as much as possible • Feedback allows learning • “Please wait” / not informative • Can utilize any of the sensory channels – Q: name sensory channels Helander 2006 Principle 5. Consider Individual Differences • Big ranges! • Time • Skill • Cognitive ability Helander 2006 Principle 6. Direct Manipulation • E.g. Xerox Star from late 60’s (Windows) A) Directness through visibility B) Semantic directness • simple icons or text if icon is unclear C) Directness through fluid action • e.g.click and drag Feature creep Helander 2006 Autopilot Design Pilot in deadly Canadian military helicopter crash unaware of flight-control software conflict, says report A CH-148 Cyclone maritime helicopter such as this crashed in the Ionian Sea last year, killing six. (Andrew Vaughan/Canadian Press) https://www.cbc.ca/news/politics/cyclone-crash-report-greece-1.6082716 Killed by Design Clockwise from top left: Capt. Kevin Hagen, Sub-Lt. Abbigail Cowbrough, Capt. Brenden Ian MacDonald, Master Cpl. Matthew Cousins, Sub-Lt. Matthew Pyke, Capt. Maxime MironMorin. (Department of National Defence) F 5.6 Main Features of Situation Awareness •Difficult to evaluate •need simulator, lab Helander 2006 Situation Awareness 1. Perception 2. Comprehension 3. Projection (Anticipation) Figure 5.6 Helander 2006 BOEING 737 MAX Distasters Boeing CEO admits faulty sensor triggered automatic flight control system in deadly crashes PILOTS not aware MCAS control over-ride system even existed https://abcnews.go.com/International/boeing-ceo-admits-faulty-sensor-triggered-automatic-flight/story?id=62191006 https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-crashes.html Developing Usable Design • Design tools – eraser and sledgehammer (Frank Lloyd Wright) • Use concurrent design – interface along with all else • Cases: Google, ipod – simple and effective interfaces • Usability sells • Cheap to integrate usability early in design • Table 7.3 - Checklist for Early User Testing Helander 2006 T 7.3 Early User Testing Checklist □ Sketch user scenarios w user & system messages □ Show sketches to a few prospective users □ Begin writing user manual □ Use simulations to test functions & org. of user interface □ Use mockups □ Invite comments on usability components □ Ask users to think aloud while using sims & prototypes □ Use hallway and storefront methods □ Do formal prototype user testing □ Meet behavioral benchmarking □ Do field studies □ Do follow-up studies on people who use the system Helander 2006 UE Usability Evaluation Methods • Heuristics Evaluation • Cognitive Walkthrough • GOMS (GMSO) • Usability Testing • User Participatory Design • Think Aloud Protocols • Questionnaires & Interviews theletter.co.uk >>> Helander 2006 Heuristic Evaluations UE • Refer to given rules/goals • A quick check • ‘Expert’ or designer based examination of rule compliance • Example of Usability Rule Checklists: • Shneiderman's Eight Golden Rules. figure 7.4 • Nielsen's Ten Usability Heuristics. figure 7.5 Helander 2006 • What ’RULES’ or heuristics would you make for software/systems design? UE T 7.4 Shneiderman's Eight Golden Rules 1. Strive for consistency 2. Enable frequent users to use shortcuts 3. Offer informative feedback 4. Design dialogues to yield closure 5. Offer error prevention and simple error handling 6. Permit easy reversal of actions 7. Support internal locus of control (user in control of the system) 8. Reduce short-term memory load Helander 2006 UE T 7.5 Nielsen's Ten Usability Heuristics 1. Visibility of system status 2. Match between system and the real world 3. User control and freedom 4. Consistency and standards 5. Error prevention 6. Recognition rather than recall 7. Flexibility and efficiency of use 8. Aesthetic and minimalist design 9. Help users recognize, diagnose, and recover from errors 10. Help and documentation >>> Helander 2006 1. Visibility of system status UE • The system should always keep users informed about what is going on, through appropriate feedback within reasonable time. Helander 2006 UE 2. Match System and the Real World • The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. • Follow real-world conventions, making information appear in a natural and logical order. Helander 2006 3. User control and freedom UE • Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. • Support undo and redo. Helander 2006 UE 4. Consistency and standards • Users should not have to wonder whether different words, situations, or actions mean the same thing. • Follow platform conventions. Helander 2006 5. Error prevention UE • Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Helander 2006 UE 6. Recognition rather than recall • Make objects, actions, and options visible. • The user should not have to remember information from one part of the dialogue to another. • Instructions for use of the system should be visible or easily retrievable whenever appropriate. Helander 2006 UE 7. Flexibility and efficiency of use • Accelerators-unseen by the novice user may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. • Allow users to tailor frequent actions. Helander 2006 UE 8. Aesthetic and minimalist design • Dialogues should not contain information which is irrelevant or rarely needed. • Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. (what law applies here?) Helander 2006 UE 9. Help users recognize, diagnose, recover from errors • Error messages should be expressed in plain language (no codes) • Precisely indicate the problem, and constructively suggest a solution Helander 2006 10. Help & documentation UE • Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. • Any such information should be easy to search, should focus on the user's task, should list concrete steps to he carried out, and should not be too large. Helander 2006 T 7.7 Usability Evaluation Methods Compared Characteristic Test users Cognitive Walkthrough No Heuristics Evaluation No User Thinking GOMS Testing Aloud No Yes Yes Task specific Yes No Yes Yes Traces correct paths Yes No Yes Maybe Maybe Assigns reasons for errors Yes Maybe No Maybe Yes Analyses user mental Processes Yes No Yes No Estimates learning time Maybe Maybe Yes Maybe Maybe Estimates performance No Yes Yes Helander 2006 No Yes Maybe Maybe time Cognitive Walkthrough UE • At any design stage 1. Performed by analyst – analyst judgment 2. Examines specific tasks 3. Analyst investigates correct action sequences 4. Identify possible trouble spots 5. Analyst reproduces mental process of imagined user (user centered) (Similar to ‘Scenario analysis’ discussed in labs) Helander 2006 Steps of a Cognitive Walkthrough UE I. Prepare your SCENARIO • • Define user knowledge Specify task and action sequence (via Task analysis) II. Analysis • Construct and check on success story (+ p.133) III. Record problems • • Identify failure stories Attend to assumptions about the ‘user’ Helander 2006 Use ’Personas’ in Scenarios • A persona is a fictional person who represents a major user group • Personas help you identify major user groups and their relevant characteristics • Companies using persona’s report: – a better understanding of customers – shorter design cycles – improved product quality • Use Personas with Task Analysis & Scenarios http://www.usability.gov Usability Testing UE • Focus on usability • Participant is (potential) end user • valid sample? • May use ‘think aloud’ • Data recorded and analyzed • How to analyze? Measures? • Efficiency, effectiveness, satisfaction (definition usability) • Deficit Severity >> Helander 2006 >> Deficit Severity UE 1. Fail to complete task 2. Delayed completion 3. Minor effect 4. Possible enhancement Consider also: • • • • • Helander 2006 frequency impact persistence market effect differences between users F 7.4 Usability Lab at Nanyang U Helander 2006 UE Usability Testing - Four Things to Keep in Mind 1. Testing the Site NOT the Users 2. Performance vs. Subjective Measures 1. Don’t always coincide 3. Make Use of What You Learn 4. Find the Best Solution Helander 2006 UE User Participatory Design • Muller et al 1997 • 61 methods for PD Design phases: • Requirements definition • Conceptual design • Detailed design Helander 2006 UE Participatory Design Pros & Cons Helander 2006 UE Participatory Design Pros & Cons Pros Cons Accurate Task Info Time consuming Democratic Decision Making Designer forced to compromise design goals Users don’t understand HCI Users don’t understand consequences of poor design Sense of participation Possible better user acceptance Helander 2006 Participation in design Participation is crucial to get insights and support for the design YOU as the DESIGNER need to bring other skills and perspectives to human centred design. People have knowledge and insights you lack in the system and use of the design – consult broadly and listen carefully Think Aloud Protocols UE • Follow users thoughts while using device • Some load from secondary task (talking) • Useful! Helander 2006 Questionnaires UE • Evaluate subjective impressions • Choose questions and scales carefully – test Q’s • Example: Figure 7.5 Helander 2006 F 7.5 Using Scale Rating • Test first on a few users! • Think about appropriate wording! • Consider a scale of 1 – 7 Helander 2006 Comparison of Methodologies Types of Problems: • Skill-based performance • Rule-based performance • Knowledge-based performance Different methods tap into different problems Helander 2006 Cost Effectiveness of Usability • Fewer Errors • Greater Satisfaction – users & co-users • Faster Maintenance • Fewer Accidents • Competitive Advantage Helander 2006 Airline seating: User Experience? F 7.3 Interface of Saab Cockpit Helander 2006
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