HCI Examinable
Definition of HCI according to ACM
"Human-computer interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them."
What is Norman's Invisible Computer?
"Personal" computer is "massive, impersonal, abrupt and rude", used mostly to do social things and not for computing A device that does everything will be convenient but will probably perform worse than specialised devices: Norman suggests technology should move towards "information appliances", i.e. many items serving specific needs: - 'Home financial centre' in right location with right connections - Displays providing weather, news, sports (compare to clock) - 'Foreview' mirror in cars for traffic, parking spots "Devices that are easy to use, not only because they will be inherently simpler, but because they fit the task so well that to learn the task is to learn the appliance."
List the 8 evaluation approaches. How to approach evaluation in each one?
* Analytical evaluation (by experts) * Cognitive walkthrough (e.g. Polson, 1992) * Heuristic evaluation (e.g. Nielsen & Molich) * Model-based evaluation (e.g. GOMS) * Usability testing (controlled conditions) * Hypothesis test * Field studies (natural conditions) * Ethnomethodology
What aspects of the interface can we use to increase the sense of interaction with an agent?
* Appearance * Natural interaction cues such as gaze, gesture, body language * High level dialogue (both content and fluency) * Expression (and perception) of emotions * Exhibiting distinctive personality * Displaying behavioural competence * Showing social competence
What is the point of deriving conceptual models?
A problem of task analysis
Name some things to integrate in website navigation
* Change colour of followed links [3*] * Don't open links in new windows [9*] * Using breadcrumbs or progress bars * Link to home or menu * Usable search [1*] - Should be tolerant to minor errors - Should return in relevant order * Informative link titles - N.B. software for blind will read list of links on page - not helpful if they all say 'click here' - * Don't overly tax short-term memory - Keep number of links in hierarchy to minimum * Support episodic memory - Allow search by history
What are the distinguishing features of a Distributed Cognition?
* Having the right representation of a task or problem can allow direct solution by our perceptual system * Cognition is not just 'in the head' but is 'distributed' between internal and external representations (Hutchins, 1995) * Re-representation is important component of task achievement (e.g. sorting a hand of cards)
What are some possible errors caused by poor mental models?
* Inaccurate mental models can propagate errors in judgement and system design. * result in errors of action, and, finally, result in poor performance. * Shifting mental models requires real work. Because so many of our mental models lie hidden beneath the fabric of corporate life, shifting course can be difficult.
List the 7 data gathering methods
* Interviews * Focus Groups (getting feedbackers together to discuss) * Questionnaires * Surveys * Observation in the field * Indirect Observation * Experiment
What are three limitations of long term memory?
* Not everything is stored * Not everything stored can be retrieved * Not everything recalled is correct
What does cognitive processing involve?
* Perception * Attention * Memory * Learning * Language * Problem Solving
Describe three issues with qualitative analysis
* Validity: how much can we generalise from a few examples; are these interactions representative? * Reliability: would another evaluator reach the same conclusions? * Lack of structure in conclusions drawn: are these more than just a random collection of issues?
List factors affecting perceived agency.
* appearance * natural interactions (verbal and nonverbal) * expression of emotion and personality * behavioural competence (intentional and human-like behaviours) * social competence -- At minimum, classify user's intentions or capabilities to interact with appropriate responses -- A richer model of users beliefs, goals and desires, and how they change over time will provide richer interaction
Provide a list of natural interaction cues
* facial expressions and head orientations * gaze direction * gestures and body movements * speech and other vocal cues
What goes in a system description?
* the (user-level) concepts to be created and manipulated, which map to: -- Objects: including both agents and passive objects -- Actions: which can be initiated by agents (need task allocation) * the relationships between concepts: -- Conceptual relations, typically taxonomic, e.g. classification (X is a Z) or hierarchical (Y is a part of X), or ordered (action A must occur before action B) -- Communicative relations, how information/data passes between objects/agents or one thing affecting another.
Outline 2nd HCI Paradigm - Classical cognitivism Information Epoc Metaphor of interaction Central goal of interaction Typical questions of interest Appropriate Disciplines for interaction Desirable methodologies Legitimate kinds of knowledge How do you know if something is true? What are its values?
+ Metaphor of interaction: Interaction Information Transfer + Central Goal for interaction: Optimise accuracy and Efficiency of Information transfer + Typical Questions of Interest: What mismatches arise in communication between humans and computers? How can we accurately model what people do? How can we improve efficiency of HCI? +Appropriate Disciplines for Interaction: Laboratory and Theoretical Behavioural Science + Desirable Methodologies: Verifiable Quantitative design and evaluation methods that can be applied regardless of context + Legitimate kinds of Knowledge: Objective facts and models with general applicability + How do you know something is true: You confirm or refute your hypothesis based on statistical analysis of evidence +Values: Optimisation Strive for Objective Abstract, Quantitative, Generalizable knowledge wherever possible Principled evaluation is a priori better than ad hoc, since design can be structured to suit this paradigm. Structured design better than unstructured Reduce ambiguity, top down view of knowledge
Outline 1st HCI Paradigm - Human Factors Engineering Epoc Metaphor of interaction Central goal of interaction Typical questions of interest Appropriate Disciplines for interaction Desirable methodologies Legitimate kinds of knowledge How do you know if something is true? What are its values?
+ Metaphor of interaction: Interaction as Machine Coupling + Central goal of interaction: Optimise fit between man and machine + Typical questions of interest: How can we fix specific problems that arise in Interaction? + Appropriate Disciplines for interaction: Engineering, programming, ergonomics + Desirable methodologies: cool hacks + Legitimate kinds of knowledge: pragmatic objective details + How do you know if something is true: You tried it out and it worked + Values Reduce errors, make it work Ad hoc is OK Cool hacks that exploit a specific instance are desired
Outline 3rd HCI Paradigm: Embodied Cognition Interaction Epoc Metaphor of interaction Central goal of interaction Typical questions of interest Appropriate Disciplines for interaction Desirable methodologies Legitimate kinds of knowledge How do you know if something is true? What are its values?
+ Metaphor of interaction: Interaction as phenomenologically situated + Central Goal for Interaction: Support of situation Action in the world + Typical Questions of Interest: What existing situated activities we should support? How do users appropriate technology? How can we support interaction with constraining it by what a computer can do/understand? What is the wider context roles, politics and values? + Appropriate Disciplines for Interaction: Ethnography, Action Research, I think I , Interaction Design, User Centered Design + Desirable Methodologies: A palette of situated design and evaluation strategies Legitimate kinds of Knowledge: Thick Description of Context and Stakeholder Concerns + How do you know if something is true: You argue about relationship between your data and what you seek to understand. + Values: * Construction of meaning is intrinsic to and unfolds from interaction. * What goes around systems is more interesting that what's happening at the interface. * "Zensign" - what you don't build is as important as what you do build * Goal is to grapple with the full complexity around the system. * Knowledge can not just be a powerful abstraction but can be embedded in the world as hidden context and tacit skill which is revealed through engagement.
What are some usability issues for websites?
- If your site is difficult to use - people leave - If it is not clear what is offered - people leave - If it is hard to read - people leave - If it is unattractive - people leave - If it is boring - people leave - If they get lost - people leave - If they get frustrated - people leave - If it doesn't work the way they are used to - people leave - If its slow to load -people leave
Explain learnability
-The ease with which new users can begin effective interaction and achieve maximal performance
What are the three distinct mental models?
1. User Model 2. Designer/Interface Model 3. System image Model They should have a clear relationship Knowledge is sometimes described as a mental model: How to use the system (what to do next) What to do with unfamiliar systems or unexpected situations (how the system works)
What is stage analysis and what are its three states?
A 'task' can be defined as the activities required to obtain a particular goal in a particular domain • Could view as description of user's procedural memory (or what should end up in their memory) * Defining purpose and scope * Obtaining data * Extracting activity lists
What is a scenario and why are scenarios needed?
A scenario is an informal narrative description of a specific interaction, usually with a real-world setting. It is needed because: * Scenarios can: -- be elaborated down to low-level interactions -- suggest desirable constraints such as response time, error behaviour * May make use of personas, prototypical users * Non-essential details help things appear real, avoid designers falling into "if it was me" trap.
Describe features of situated cognition
Activities are situated in physical and socio-cultural situations What we do at any time may reflect moment-by-moment shaping by situation more than any rational goal-oriented plan E.g. web browsing Standard cognitive models tend to assume categories ('target', 'card slot') but "what we perceive as properties and events is constructed in the course of coordinated activity" Clancey 1994 -- I.e. need physical and social experience of cards and slots to recognise a card slot
What is an Affordance?
Affordance: a relation between agent, object and task "If a door handle needs a sign, then its design is faulty" D. Norman, information about complex internal states of a computer needs to be transformed into a surface representation for the user "Things may suggest by their shape and other attributes what you can do with them" Note that affordances are not intrinsic but depends on the background and culture of users. Most computer-literate users will clock on an icon. Double clicking a button not very intuitive Helps learnability!
What is ethnography?
An ethnographer is meant to capture the "social meanings and ordinary activities"of people (informants) in "naturally occurring settings" that are commonly referred to as "the field." . Observation, field study...
What are some perceptual effects vs other factors?
Bottom up visual processing sets some constraints on optimal layouts, but must also consider top down issues: - Cultural and learned factors - familiarity Underlying domain knowledge of user - Need to reflect logical structure, e.g., placement and grouping according to function, sequence, frequency of use - Dependence on task to be carried out, e.g. getting an overview vs. seeking specific information
Describe short term capacity
Capacity of STM: 7±2 chunks of information. -- Doesn't apply to menu items!
What is rich interaction and how does it differ from conventional HCI?
Conventional HCI * One user interacting with one (simple) software system * Making a sequence of discrete interactions, following internal plan towards a predefined goal * User actions reliably change world, and user reliably knows this Most real interaction is much richer: *Involves continuous close coupled loops; users are embodied * Actions and events have real time courses; users deal with interleaving, interruptions, shifts in attention etc. * Occurs in environmental context of rich representational artifacts * Occurs in context of communication with other users * Occurs in cultural/organisational context
What is the decision formula called and what is it?
Decision making: Hick-Hyman law:T=a+b*Log₂(n+1) -- n - # of options -- T - time to make a decision
Describe declarative vs Prodedural memory
Declarative * Episodic: what happened, where and when * Semantic: factual information, general knowledge, independent of context Procedural * How-to-do-it knowledge; usually implicit, hard to put in words. HENCE non-declarative (how to ride a bicycle)
What is Distributed Cognition?
Distributed Cognition is the process in which cognition resources are spread across people, places, interfaces and representations. It is concerned with the nature of cognitive phenomena across individuals, artifacts, and internal and external representations. Information is transformed through different media in Distributed Cognition. E.g. a wizard to externalise a plan; requires the user to internalise the history
How to measure improvement of information layout?
Effects of improved web writing: - Measured: • Task time: to find answers for specific questions about the content. • Errors: percentage of incorrect answers • Memory: items recalled or recognised after using the site. • Time to recall site structure: sketch site map • Subjective satisfaction: questionnaire with rating scales for site's perceived quality, perceived ease of use, likeability and user affect.
Sketch Don Norman's 7 stage model. What is it used for?
Evaluation by designers: Cognitive walkthrough involves stepping through an interaction sequence from the user's perspective Can occur at any stage, but particularly useful early in design (e.g. can apply to mock-up, prototype or not fully functional systems)
Describe an interaction context from a Distributed Cognition perspective
Example interaction context: flying to higher altitude in a plane - coordinated activity of an air traffic controller, a co-pilot and a pilot. - The air traffic controller tells the co-pilot over the radio when it is safe to fly to a higher altitude. This is an instance of a propagation of representational state, involving verbal communication. - The co-pilot then alerts the pilot, who is flying the plane, by moving a knob on the instrument panels in front of them, indicating that it is now safe to fly. This is the next step of the propagation of representational state, but this time in terms of a physical change in the position of an instrument. - The pilot now controls the plane to fly to a higher altitude.
State Fitt's law and describe what each term is and what their relationships mean.
Fitt's Law is a model for predicting the amount of time a user will take to move to a target area based on distance and target size: Time = a + b*log₂((Distance / Width)+1) Where a & b are constants based on context (ie pointing device, environment) Time decreases with increased width Time decreases with decreased distance
What are formal methods and for what tasks are they appropriate?
Formal methods are "being able to represent things in such a way that the representation can be analyzed and manipulated without regard to the meaning. This is because the representation is chosen to encapsulate faithfully the significant features of the meaning." - Dix 2003
Describe functionality, experience and problems in terms of evaluation
Functionality: Assess the extent and accessibility of the system's functionality. (i.e. the design of the system should enable users to perform their intended tasks more easily) Experience: Assess users' experience of the interaction and its impact upon the user. (e.g. how easy the system is to learn, its usability and the user's satisfaction with it, Is the experience enjoyable) Problems: Identify any specific problems with the system. (e.g. unexpected results, confusion amongst users, bugs
List types of context cues
Gaze, gesture, body language - Time location
Formal Methods: Goms. What is it a form of?
Goms - Goals, Operators, Methods, Selection rules * Goals - what the user wants to achieve eg. find a website. * Operators - the cognitive processes & physical actions needed to attain goals, eg. decide which search engine to use. *Methods - the procedures to accomplish the goals, eg. drag mouse over field, type in keywords, press the go button. * Selection rules - decide which method to select when there is more than one. A form of task analysis!!
Define distributed cognition. Explain an interaction from the point of view of distributed cognition with its features - multiple people, artefacts etc.
Having the right representation of a task or problem can allow direct solution by our perceptual system Cognition is not just 'in the head' but is 'distributed' between internal and external representations (Hutchins, 1995) Best example: Airline co-pilot communication. Verbal + physical indicator.
What are the three paradigms of HCI?
Human Factors Engineering Epoc - Classical Cognitive Information Epoc - Embodied/Situated Interaction Epoc
What is the uncanny valley?
Human-like but not quite human systems may fall into the 'uncanny valley' (a sudden drop of familiarity when the human likeness of an agent reaches around 90%)
Computer agents: Reasons to engage anthropomorphism
Humans are already expert at social interaction * Already know the 'language' -> effortless communication * Feel competent working in this domain, reduces anxiety Can grab attention, seem more fun Provides emotional engagement * 'Affective' computing
Modes of Interaction: Give examples of Instructing, Conversing, Manipulation and Exploration
Instructing: * Shell command line interpreters for operating systems * Menu and key-driven GUI shells for OS's and applications * VCRs, hi-fis, alarm clocks, vending machines, etc. Conversing: Help facilities (Microsoft's Office Assistant paper clip, Bob) * Search engines (http://www.ask.com, although Jeeves has now retired) * Phone services (voice recognition query answering/navigation) * Virtual shopping or support assistants Manipulation: desktop files metaphor - dragging and dropping * also true manipulable objects: physical objects with sensors (e.g. Wii controller) Exploration: * 3D desktop virtual worlds where people navigate using mouse around different parts to socialize (e.g., Second Life) * physical context-aware environments, embedded with sensors, that present digital information to users at appropriate places and times (e.g. cell phone tourism, smart home)
What is interact design? How does it differ to older examples of HCI and a linear design process?
Interact Design: A Process for Creating Digital Interactive Systems for people to Interact and Communicate during their Everyday and Working Activities How does it differ: heavily focused on satisfying the needs and desires of the people who will use the product
What is KSM?
Key-Stroke Model! Measures how quick an expert system can perform a task. Depth of hierarchical goal structure reflects complexity and memory load of task Can predict likely sequence of actions (but not mistakes) Most appropriate for: • Goal-directed interactions (e.g. not browsing) • Routine skill performance (e.g. not discovery) • Sequential instructional interactions • Capturing internal procedural knowledge Can use to validate hypotheses about interaction processes Timings e.g. 100-1000ms per normal key. mousepress 100ms, release 100ms etc
What are Dix's three principles of design rule classifications?
Learnability * the ease with which new users can begin effective interaction and achieve maximal performance (e.g. familiarity, generalisability, predictability) Flexibility * the multiplicity of ways the user and system exchange information (e.g. customizability, substitutability, user control) Robustness * the level of support provided to the user in determining successful achievement and assessment of goal-directed behaviour (e.g. observability, recoverability)
State three types of limitations of reflective cognition and describe them briefly
Logical reasoning: people are poor at it Decision making: Hick-Hyman law:T=a+b*Log₂(n+1) -- n - # of options -- T - time to make a decision N.B. apparent advantage of broad shallow menus applies only if the list is logically ordered (e.g. alphabetical) For unfamiliar random order list, decision time is linear with n.! Confirmation: people tend to search for confirmation for a hypothesis rather than check for contradictions
Describe Ubiquitous Computing - beyond the desktop, embedded, input types, device types. How is this different to web interaction for example?
Making the computer part of the environment Mobile devices Implicit input Ambient output Continuous interaction Issues for design and evaluation
Outline the design process for websites
Many of the usability methods and issues discussed so far apply to website design: - Design process (and early involvement of users) - Information layout and perceptual factors - Application of modelling approaches - Development of principles, rules and standards - Evaluation methods But there are many web-specific usability issues: - Platform independence - have interface flexibility but less control - Content is as important as usability - Diverse user population and low average interaction time (minutes) - Many developers with very different kinds and levels of expertise (can these be supported towards more usable design?) - Often have dynamic open-ended development with feedback - Issues relating to networking: bandwidth, latency, broken links
How to apply familiarity to UI
Match the interface to the users' expectations.
State the features of the Model Human Processor. What are some limitations?
Models the information processes of a user interacting with a computer Perceptual, Motor and Cognitive sub-systems characterised by: - Storage capacity U - Decay time D - Processor cycle time T Predicts which cognitive processes are involved when a user interacts with a computer Enables calculations to be made of how long a user will take to carry out a task Limitations * Based on modelling mental activities that happen exclusively inside the head * does not adequately account for how people interact with computers and other devices in real world
List needs for information layout. Describe how to measure improvement
Need to include: - Informative title - Author/Owner - Date last modified - Link to home Need to: - Highlight keywords (hypertext links serve as one form of highlighting; typeface variations and color are others) - "Front-load" meaning - Use bulleted lists - Have one idea per paragraph - Use inverted pyramid style, starting with the conclusion - Halve the word count
How to adapt a website for use on mobile?
Nielsen - Cut Features - Cut Content - Enlarge Interface Features • Mobile vs Web site - css • apps • HTML5, Phone Gap • Mobile First • GPS, Touch, Near Field, pose sensors
What are state transition diagrams? When are they useful?
Nodes/circles represent states of the device - Edges/arcs represent inputs or actions - Example: Drawing Program FSMs! Graphs! Can apply graph theory, can create state charts (think ES) etc * useful for evaluating dialog designs prior to implementation/prototyping * very good at representing the sequential, choice and iterative parts of a dialog * fails badly in describing a dialog consisting of several concurrent parts, particularly a problem with direct manipulation interfaces (example in page 553, ch 16.3.3 Dix et al.)
Describe closed loop collapse of input/outputs. Think up a continuous interaction interface
Obtaining natural interaction may involve collapsing the usual input/ output distinction `Continuous interaction' emphasises the closed loop rather than stages of action * On more extended time scales, includes thinking of HCI in terms of extended, ongoing activities rather than tasks that have a clear beginning and end - Should support interruptions, concurrency etc. * example: tutoring systems (performances of the students will influence the instructions given by the auto tutor)
What are Shneiderman's 8 Golden rules? How did they come up?
Origin: Collections of experience 1. Strive for consistency in action sequences, layout, terminology, command use and so on. 2. Enable frequent users to use shortcuts such as abbreviations, special key sequences and macros to perform regular, familiar actions more quickly. 3. Offer informative feedback for every user action, at a level appropriate to the magnitude of the action. 4. Design dialogs to yield closure so that the user knows when they have completed a task. 5. Offer error prevention and simple error handling so that ideally users are prevented from making mistakes and if they do they are offered clear and informative instructions to enable them to recover. 6. Permit easy reversal of actions in order to relieve anxiety and encourage exploration, since the user knows that he can always recover to the previous state. 7. Support internal locus of control so that the user is in control of the system, which responds to his actions. 8. Reduce short-term memory load by keeping displays simple, consolidating multiple page displays and providing time for learning action sequences.
What are Nielsen's 10 usability heuristics? Where did they originate from?
Origin: The result of empirical study (e.g. Nielsen's heuristics are based on factor analysis of 249 usability problems) 1. Visibility of system status Always keep users informed about what is going on through appropriate feedback within reasonable time. For example=, if a system operation will take some time, give an indication of how long and how much is left to complete! 2. Match between system and the real world The system should speak the user's language with worlds, phrases and concepts familiar to the user rather than system-oriented terms. Follow real-world conventions, making information appear in natural and logical order. 3. User control and freedom Users often choose system functions by mistake and need a clearly marked 'emergency exit' to leave the unwanted state without having to go through an extended dialog. Support undo and redo! 4. Consistency and standards Users should not have to wonder whether words, situations or actions mean the same thing in different contexts. Follow platform conventions and accepted standards. 5. Error prevention. Make it difficult to make errors. Even better than good error messages is a careful design that prevents a problem from even occurring in the first place. 6. Recognition rather than recall. Make objects, actions and options visible. The user should not have to remember information from one part of the dialog to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate. 7. Flexibility and efficiency of use Allow users to tailor frequent actions. Accelerators - unseen by the novice user - may often speed up the interaction for the expert user to such an extent that the system can cater to both inexperience and experienced users. 8. Aesthetic and minimalist design Dialogs should not contain information that is irrelevant or rarely needed. Every extra unit of information in a dialog compete with the relevant units of information and diminishes their relative visibility. 9. Help users recognize, diagnose and recover from errors Error messages should be expressed in plain language (no codes), precisely indicate the problem and constructively suggest a solution. 10. Help and documentation Few systems can be used with no instructions so it may be necessary to provide help and documentation. Any such information should be easy to search, focussed on the user's task, list concrete steps to be carried out and not be too large.
What are Norman's 7 principles? Where did they originate from?
Origin: derived from particular characterisations of the nature of human action 1. Use both knowledge in the world and knowledge in the head. People work better when the knowledge they need to do a task is available externally - either explicitly or through the constraints imposed by the environment. But EXPERTS also need to be able to INTERNALIZE regular tasks to increase their efficiency. System should provide necessary knowledge within the environment and their operation should be transparent to support the user in building an appropriate mental model of what is going on. 2. Simplify the structure of tasks. Tasks need to be simple in order to avoid complex problem solving an excessive memory load. One way is to provide mental aids to help the user keep track of stages in a more complex task. Another is to use technology to provide the user with more information about the task and better feedback. 3. Make things visible bridge the gulfs of execution and evaluation. Clear view of what the system can do and how to achieve it. 4. Get the mapping right User intentions should map clearly onto system controls. User actions should map clearly onto system events. It should be clear what does what and by how much. E.g. choose controls, sliders and dials to reflect the task. 5. Exploit the power of constraints both natural and artificial. Constraints are things in the world that make it impossible to do anything but the correct action in the correct way. E.g. a jigsaw puzzle. 6. Design for error. To err is human, so anticipate the errors the user could make and design recovery into the system. 7. When all else fails, standardize If there are no natural mappings then arbitrary mappings should be standardized so that users only have to lean them once. Cut, copy , paste etc!
What are the three types of design rules? Give an example for each
Principles * Abstract design rules * e.g. "an interface should be easy to navigate" Guidelines * Advice on how to achieve principle * may conflict; understanding theory helps resolve * e.g. "Use colour to highlight links" Standards * Specific rules, measurable * e.g. "MondoDesktop links are RGB #1010D0"
Non-parametric vs parametric
Parametric => known distribution, can do more cool, funky stuff. Non-parametric less powerful
Describe how interfaces might become cognitively and physically invisible
Potential to 'eliminate' conscious interaction - E.g. remove ticket sales by tracking where people went and charging their accounts - Verichip implant - Identify patients in emergency situtation - Other uses...? Replaces interaction programming problems with ethical problems - Those without resources to be connected to system are disenfranchised - Removes option of anonymous interaction
What is a metaphor? How and why are they used in HCI?
Powerful (but risky) method in design is to exploit the human tendency to reason by metaphor, i.e. "X is like Y" Exploiting existing knowledge for learning * Need entity resemblance to prompt appropriate metaphor * Need relational resemblance to support correct mapping Users prefer 'learning by doing' or ('learning by observing') * Metaphor provides obvious clues for systematic investigation Mismatches prompt investigation and learning * Correspondences, non-correspondence and indeterminate correspondence
Explain predictability
Predictability - Determinism and operation visibility * the same action leads to the same result * visibility to user that the state has changed * Markov property: transition does not depend on history
Definite features of reflective cognition and describe them. How can we reason about / improve reflective cognition?
Problem solving: * Extrapolating from knowledge we do have (memory systems) * May be very simple, e.g. making a decision * Logical reasoning might supply the answer * Mental models can be used to predict outcomes * Reasoning by analogy or metaphor is powerful and natural
What are prototypes and what is their role?
Prototyping: The Creation of tangible manifestations of design ideas that users, designers and other stakeholders can interact with in a rapid and in an inexpensive way in design and analysis loop before implementation and deployment
Give examples of qualitative and quantitative data.
Quantitative - has structure of integers or real numbers, e.g. number of errors (discrete), time to complete task (continuous) • Not just "comprised of numeric values" e.g. numeric labels * How long did it take to find the required webpage? Qualitative - everything else, e.g. categories of action, preferences • But note may be able to quantify the number of people falling into a category or expressing the same preference. "disagree" - "agree" 1-5 * How much do you like this GUI?
How to ensure good questionnaire response?
Question ordering may matter! Encouraging a good response * Make sure purpose of study is clear * Promise anonymity * Ensure questionnaire is well designed * Offer a short version for those who do not have time to complete a long questionnaire * If mailed, include a stamped addressed envelope * Follow-up with emails, phone calls, letters * Provide an incentive * 40% response rate is high, 20% is often acceptable
Learning rate, what is the power law of practice? Describe some consequences. What is a criticism?
Reaction time: Tn = T₁n^(-a) a = 0.4[0.2 -- 0.6] I.e. improvement is rapid at first, and slows later •Has been found in a wide variety of tasks (pressing button sequences, reading inverted text, mental arithmetic, manufacturing, writing books...) Criticism (2000) Heathcote: Tn =T₁e^(-an) *Implies constant relative learning rate
What is hierarchical task analysis? How does it work?
Refining the HTA: check and improve the decomposition Some heuristics are: * Check for paired actions: where is "turn on gas"? * Restructure: generate task "make pot" * Balance: is "pour tea" simpler than "make pot"? * Generalise: make one cup . . . or more * Sub-operations should be mutually exclusive and collectively exhaustive • Consider possible alternatives
List the four Gestalt principles and briefly describe each.
Similarity: Similarity occurs when objects look similar to one another. People often perceive them as a group or pattern. Proximity: Proximity occurs when elements are placed close together. They tend to be perceived as a group. Common region: elements tend to be grouped together if they are located within the same closed region. Connectedness: elements tend to be grouped together if they are connected by other elements.
How does the mobile web differ from desktop web?
Smaller Screens Massive Diversity Speed of Connection Touch interaction
Explain synthesizability
Support for the user to assess the effect of past operations on the current state (if outcome is better or worse than expected) * Immediate vs. eventual honesty Advantage of WYSIWIG!
What are tangible interfaces? How do they differ from conventional interfaces and what benefits do they have?
Tangible input devices - manipulate 'ordinary' physical object Towards Seamless Interfaces Between People, Bits and Atoms Natural, not everything suited for a mouse and pointer. E.g. drawing tablet
What is cognitive load?
The 'Cognitive load' of a task is how much we have to keep "in mind" for that task
What is a cognitive walk through? (be able to apply one!)
The cognitive walkthrough method is a usability inspection method used to identify usability issues in interactive systems, focusing on how easy it is for new users to accomplish tasks with the system. Cognitive walkthrough is TASK-specific. The method is rooted in the notion that users typically prefer to learn a system by using it to accomplish tasks, rather than, for example, studying a manual. * Will the user try to achieve the effect that the subtask has? Does the user understand that this subtask is needed to reach the user's goal? * Will the user notice that the correct action is available? E.g. is the button visible? * Will the user understand that the wanted subtask can be achieved by the action? E.g. the right button is visible but the user does not understand the text and will therefore not click on it. * Does the user get feedback? Will the user know that they have done the right thing after performing the action?
Evaluation: Describe the issues of who, when, how, which, what and resources used. What is consistency in all of this?
WHO is giving this feedback? A design expert? A fellow programmer? A typical user or member of a target user group? Is it just one person or a significant proportion of your users? WHEN are you getting this feedback? On an early prototype or an established product? HOW has this evaluation been arrived at? Is it by comparison to some guidelines, or from a simulated walkthrough? Is it from use in a realistic context ('ecological validity')? WHICH Method of data gathering is being used? Interview,observation etc WHAT has been used as a measure? Quantitative (time to complete task, error rate) or qualitative (ease of use ratings)? Compared to recommendations or alternatives? Consistency? Resources What time, effort and money do you have to conduct the evaluation and make changes to the design?
Think up an example of a tangible interface and describe its affordances.
Wacom drawing tablets. Much easier, can detect things like hardness instead of having to hold down a button for longer..
How might the uncanny valley disturb an interaction and what can you do about it?
Weird to interact with agents in the 'Uncanny Valley'. Usability is badly compromised. Apparent agency can create false expectations . Avoid falling in the 'uncanny valley': - Design elements should match in human realism. - Reducing conflict and uncertainty by matching appearance, behavior, and ability. - Human facial proportions and photorealistic texture should only be used together.
Navigation: describe Where³What of communication
Where you are... Where you're going (or what will happen) Where you've been (or what has been done) What you can do now
Describe when evaluation is used within the design cycle. How is it carried out?
With respect to the Design Cycle * Pre-design * Early Prototype * Pilot * Product With respect to the user * Before Use * During Use * After Use Evaluation is iterative and adaptive. Repeated/different to suit needs of stage.
Describe the mental model of an ATM
Write down a mental model of how an ATM works: • What happens to prevent you taking out more than the limit by using several machines in turn? •What information is on the card itself, and how is it used? •Why are there pauses between steps, and why are they duration they are? •What happens to the card while in the machine? •Do you count the money? Why or why not?
What are the different types of agents?
anthropomorphic: human-like (NS-5 in "I, Robot") zoomorphic: animal-like (insect robots) cartoon (caricature): ???-like functional: just its original look (vacuum cleaner robot "Roomba")
What is between-subjects and within subjects?
between-subjcets, aka randomised design, each participant is assigned to a different condition. Experiment condition and conrol condition. Needs greater numbers but learning effect is under control Within-subjects (repeated measures) performs each under a different condition). Fewer users needed and less chance of effect of variation between participants.
Describe schemas, frames and scripts. write one for a situation.
schemas: pre-existing knowledge structures that shape our memory of new inputs schema concept has been formalised as: * Frames: knowledge is organised into data structures with fixed, default and variable slots or attributes (c.f. OOP) * Scripts: stereotypical knowledge about situations that allows interpretation of partial descriptions or cues (E.g. "We went to that restaurant you recommended. The food arrived quickly. We left about nine." Did they eat the food? Did they pay? Were there tables in the restaurant?) may develop as abstractions of specific experiences (episodic memory) memory of specific experiences may be shaped by a schema (episodic memory) if you have the correct Schema to hand, memory is greatly improved
What is the Conceptual Model?
the model the designer wants/expects the user to have in their head; starting point of interaction design, should help the user have the same model as the designer; a static model of the system. "Design the design, creates a lexicon for what is to be included" WHAT DOES THE USER NEED TO KNOW TO UNDERSTAND THE SYSTEM. Keep small! Metaphores etc
What are some examples of conceptual models? (should add more to these later)
user model designer/interface model system image model
What are the components of the scientific method?
• Choose something to study • Form a Theory of how it works • Form an Hypothesis consistent with the Theory • Devise an Experiment to test the Hypothesis • Perform the Experiment • Analyse the Data • Make an Inference • Confirm/Refute the Hypothesis • Confirm, Reject, Modify the Theory • Karl Popper - Conjectures and Refutations
List issues around experiments.
• Hypothesis • Experimental design • Variables - independent/ Dependent • Types of Variables • Subjects - Within/Between • Samples - paired/unpaired • Statistical technique • Assumptions • Parametric/Non- parametric techniques • CLT - why normal distribution is so common
List some guidelines for small devices
• Use(fulness) immediately apparent • Structure interface to task • Short cuts and flexibility • Minimise memory load • Use consistent screen templates • Provide a Back function on every screen • Selection is better than writing
List components of experimental design
• Variables - independent/Dependent • Types of Variables • Subjects - Within/Between • Samples - paired/unpaired • Statistical technique • Assumptions • Parametric/Non- parametric techniques • CLT - why normal distribution is so common
Describe what goes into a Conceptual model
✱metaphors and analogies: e.g., the information is organized as in a physical card-catalogue. ✱ concepts: e.g., item (with attributes: title, ISBN, status; with actions: check-out, check-in, reserve), subtypes of item (e.g., book, periodical issue, LP, video), periodical volume, user account (with attributes: name, items checked out), librarian; ✱ relationships: e.g., a book is one type of item, periodical volumes contain issues; ✱ mappings: e.g., each item in the system corresponds to a physical item in the library; They are supposed to be expressed in a system-neutral way, so as not to specify the design of the system. The Objects/Actions analysis, therefore, is a declaration of the concepts that are exposed to users. "If it isn't in the conceptual model, the system should not require users to be aware of it."
