HCI Cognitive Mental Model PDF

HUMAN COMPUTER INTERACTION Dr. Bassam Hammo & Ammar El- Hassan  Cognition & Mental Models Agenda √Discuss Norman’s views on HCI & design  Today Cognition & Mental Models Overview  What is the human side of HCI?  What are “Human Factors”?  What is cognitio...

HUMAN COMPUTER INTERACTION Dr. Bassam Hammo & Ammar El- Hassan  Cognition & Mental Models Agenda √Discuss Norman’s views on HCI & design  Today Cognition & Mental Models Overview  What is the human side of HCI?  What are “Human Factors”?  What is cognition?  What are users good and bad at?  Describe how cognition is applied to interaction design  Theories of cognition ◦ Mental models, theory of action ◦ Information processing ◦ External cognition, distributed cognition What is the human side of HCI?  What are the human considerations that we need to take into account when designing computer applications (and hardware)?  Put it in another way: what do you need to know about specific users (and humans in general) in order to make the interaction between humans and computers as effective as possible? Everyday Problem  We all get mad with our computers when something goes wrong or when a program is not “user friendly” in the sense that we cannot easily find the solution to a problem.  Most of you are typical users. The software you are frustrated with was probably designed with you in mind. Everyday Problem (cont.) Questions: a) What exactly did the designers have in mind when they designed that program? b) Did they consider that a typical user might be using it? Preview  We are going to examine Human Factors, a broader field of study which encompasses HCI, and looks at User Considerations for all types of tools we interact with.  Then we’ll explore what Cognitive Psychology has to contribute to the field. What are “Human Factors”?  The study of how humans accomplish work-related tasks in the context of human-machine system operation, and how behavioral and non-behavioral variables affect that accomplishment ◦ “behavioral” refers to psychological constraints - how do humans process information? ◦ “non-behavioral” refers to physical constraints - can a human physically work a control?  Emphasis in Human Factors is on design - how should a system be designed to accommodate a human operator? What are “Human Factors”?  Human factors professionals develop models of human performance that can aid designers of human-machine systems. Contributing Fields: How does “Human Factors” differ from Experimental Psychology?  Experimental Psychology is the scientific study of mind, brain, and behavior ◦ Why do humans think and behave the way they do?  Human factors is the study of human behavior in the context of technological systems ◦ How should we design a system to accommodate the way humans think and behave? Why Human Factors are important to Computer Science?  Human Factors psychology examines the capabilities of humans and how these constraints vs abilities affect design.  Therefore, it is concerned with cognitive issues and research concerning humans’ interpretation of stimuli and our abilities to deal with certain situations.  The goal is to design systems with these capabilities and limitations in mind. “Human Factors” applies principles of Cognitive Psychology:  Cognitive issues that must be considered: ◦ Memory (span, retrieval, storage capacity) ◦ Visual and auditory capabilities/interpretations ◦ Attention capacity (selective, focused, divided) ◦ Judgment of tones, size, loudness, brightness ◦ Interpretation of coding (traffic lights, error icons, info icons, etc.) Human Factors applies principles of Cognitive Psychology : (cont.)  Cognitive issues that must be considered: ◦ Response time to stimuli ◦ Problem solving abilities ◦ Decision making ◦ Language comprehension ◦ Disabilities ◦ Cognitive load Human Considerations in Software Design  What do we need to know about each user in order to make the software that s/he is using accessible?  What kinds of things do we need to consider in our designs?  What do we know about PSYCHOLOGY that will guide our designs? Human Considerations in Software Design 1. Visual perception, memory, prior knowledge 2. Cognitive load, distractions (attention), non-expert user (help!) 3. Accessible keyboards, alternative input devices 4. Bigger keys Again...why do we need to understand users?  Interacting with technology is cognitive? Not exclusively!  We need to take into account cognitive processes involved and cognitive limitations of users  We can provide knowledge about what users can and cannot be expected to do  Identify and explain the nature and causes of problems users encounter  Supply theories, modelling tools, guidance and methods that can lead to the design of better interactive products Core cognitive aspects  Attention  Perception and recognition  Memory  Reading, speaking and listening  Problem-solving, planning, reasoning and decision-making, learning  Most relevant to interaction design are attention, perception and recognition, and memory What goes on in the mind? Attention  Selecting things to concentrate on at a point in time from the mass of stimuli around us  Allows us to focus on information that is relevant to what we are doing  Involves audio and/or visual senses  Focused and divided attention enables us to be selective in terms of the mass of competing stimuli but limits our ability to keep track of all events  Information at the interface should be structured to capture users’ attention, e.g. use perceptual boundaries (windows), color, reverse video, sound and flashing lights Activity: Find the price of a double room at the Holiday Inn in Bradley Activity: Find the price for a double room at the Quality Inn in Columbia Activity  Tullis (1987) found that the two screens produced quite different results ◦ 1st screen - took an average of 5.5 seconds to search ◦ 2nd screen - took 3.2 seconds to search  Why, since both displays have the same density of information?  Spacing ◦ In the 1st screen the information is bunched up together, making it hard to search ◦ In the 2nd screen the characters are grouped into vertical categories of information making it easier Design implications for attention  Make information salient when it needs attending to  Use techniques that make things stand out like color, ordering, spacing, underlining, sequencing and animation  Avoid cluttering the interface - follow the google.com example of crisp, simple design  Avoid using too much because the software allows it Perception and recognition  How information is acquired from the world and transformed into experiences  Obvious implication is to design representations that are readily perceivable, e.g. ◦ Text should be legible ◦ Icons should be easy to distinguish and read Is color contrast good? Find Italian Are borders and white space better? Find French Activity  Weller (2004) found people took less time to locate items for information that was grouped ◦ using a border (2nd screen) compared with using color contrast (1st screen)  Some argue that too much white space on web pages is detrimental to search ◦ Makes it hard to find information Which is easiest to read and why? Design implications  Representations of information need to be designed to be perceptible and recognizable  Icons and other graphical representations should enable users to readily distinguish their meaning  Bordering and spacing are effective visual ways of grouping information  Sounds should be audible and distinguishable  Speech output should enable users to distinguish between the set of spoken words  Text should be legible and distinguishable from the background  Memory  Involves first encoding and then retrieving knowledge  We do not remember everything - involves filtering and processing what is attended to  Context is important in affecting our memory (i.e., where, when)  Well known fact that we recognize things much better than being able to recall things ◦ Better at remembering images than words ◦ Why interfaces are largely visual? Memory components  Sensory Memory < 1 second  Short-term (Working Memory) 10-15 seconds  Long-term Memory Years  [demonstrations] Sensory memory D H F G V J S A L K O P Sensory memory M R T J A F K P Z D N O Short term (working) memory  Capacity o Miller’s Magic Number 7 ± 2  Serial effects Long term memory  Semantic Memory - Concepts ◦ Recognition vs. recall  Episodic Memory - Things that happened  Procedural Memory - Skilled behavior Processing in memory  Encoding is first stage of memory ◦ determines which information is attended to in the environment and how it is interpreted  The more attention paid to something,  And the more it is processed in terms of thinking about it and comparing it with other knowledge,  The more likely it is to be remembered ◦ e.g., when learning about HCI, it is much better to reflect upon it, carry out exercises, have discussions with others about it, and write notes than just passively read a book, listen to a lecture or watch a video about it Context is important Context affects the extent to which information can be subsequently retrieved  Sometimes it can be difficult for people to recall information that was encoded in a different context Activity  Try to remember the dates of your grandparents’ birthday  Try to remember the cover of the last two DVDs you bought or rented  Which was easiest? Why?  People are very good at remembering visual cues about things ◦ e.g., the color of items, the location of objects and marks on an object  They find it more difficult to learn and remember arbitrary material ◦ e.g., birthdays and phone numbers Recognition versus recall  Command-based interfaces require users to recall from memory a name from a possible set of 100s  GUIs provide visually-based options that users need only browse through until they recognize one  Web browsers, MP3 players, etc., provide lists of visited URLs, song titles etc., that support recognition memory Miller’s Magic Number 7 ± 2  George Miller’s theory of how much information people can remember  People’s immediate memory capacity is very limited  Many designers have been led to believe that this is useful finding for interaction design What some designers get up to…  Present only 7 options on a menu  Display only 7 icons on a tool bar  Have no more than 7 bullets in a list  Place only 7 items on a pull down menu  Place only 7 tabs on the top of a website page  But this is wrong? Why? Why?  Inappropriate application of the theory  People can scan lists of bullets, tabs, menu items till they see the one they want  They do not have to recall them from memory having only briefly heard or seen them  Sometimes a small number of items is good design  But it depends on task and available screen estate Design implications  do not overload users’ memories with complicated procedures for carrying out tasks  Design interfaces that promote recognition rather than recall  Provide users with a variety of ways of encoding digital information to help them remember where they have stored them ◦ e.g., categories, color, flagging, time stamping Mental models  Users develop an understanding of a system through learning and using it  Knowledge is often 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)  People make inferences using mental models of how to carry out tasks  Everyday reasoning and mental models a) You arrive home on a cold winter’s night to a cold house. How do you get the house to warm up as quickly as possible? Set the thermostat to be at its highest or to the desired temperature? b) You arrive home starving hungry. You look in the fridge and find all that is left is an uncooked pizza. You have an electric oven. Do you warm it up to 375 degrees first and then put it in (as specified by the instructions) or turn the oven up higher to try to warm it up quicker? Heating up a room or oven that is thermostat-controlled  Many people have erroneous mental models (Kempton, 1996)  Why? ◦ General valve theory, where ‘more is more’ principle is generalised to different settings (e.g. gas pedal, gas cooker, tap, radio volume) ◦ Thermostats based on model of on-off switch model Heating up a room or oven that is thermostat-controlled  Same is often true for understanding how interactive devices and computers work: ◦ e.g. elevators and pedestrian crossings - lot of people hit the button at least twice ◦ Why? Think it will make the lights change faster or ensure the elevator arrives!  Exercise: ATMs  Write down how an ATM works ◦ How much money are you allowed to take out? ◦ What denominations? ◦ If you went to another machine and tried the same what would happen? ◦ What information is on the strip on your card? How is this used? ◦ What happens if you enter the wrong number? ◦ Why are there pauses between the steps of a transaction? What happens if you try to type during them? ◦ Why does the card stay inside the machine? ◦ Do you count the money? Why? Norman’s (1986) Theory of action  Proposes 7 stages of an activity ◦ Establish a goal ◦ Form an intention ◦ Specify an action sequence ◦ Execute an action ◦ Perceive the system state ◦ Interpret the state ◦ Evaluate the system state with respect to the goals and intentions An example: reading breaking news on the web 1. Set goal to find out about breaking news decide on news website 2. Form an intention check out BBC website 3. Specify what to do move cursor to link on browser 4. Execute action sequence click on mouse button 5. Check what happens at the interface see a new page pop up on the screen 6. Interpret it read that it is the BBC website 7. Evaluate it with respect to the goal read breaking news How realistic?  Human activity does not proceed in such an orderly and sequential manner  More usual for stages to be missed, repeated or out of order  Do not always have a clear goal in mind but react to the world  Theory is only approximation of what happens and is greatly simplified  Help designers think about how to help users monitor their actions Cognitive/User Modeling  Idea: If we can build a model of how a user works, then we can predict how s/he will interact with the interface Components  Model some aspects of user’s understanding, knowledge, intentions and processing  Vary in representation levels: high level plans and problem-solving to low level motor actions such as key-presses Differing Approaches  Many different modeling techniques exist ◦ Human as information processing machine Many subfamilies and related models ◦ Human as actor in context Situation action, Activity theory, Distributed cognition Human Information Processing  Conceptualizes human performance in metaphorical terms of information processing stages Attention Memory  Externalizing to reduce memory load  Diaries, reminders, calendars, notes, shopping lists, to-do lists - written to remind us of what to do  Post-it, piles, marked emails - where placed indicates priority of what to do  External representations: ◦ Remind us that we need to do something (e.g. to buy something for mother’s day) ◦ Remind us of what to do (e.g. buy a card) ◦ Remind us when to do something (e.g. send a card by a certain date) Next time Design with the Users