Human Computer Interaction - HCI Understanding Users PDF

HUMAN COMPUTER INTERACTION Dr. Bassam Hammo & Dr. Ammar El- Hassan Understanding Users Agenda  Discuss Norman’s views on HCI & design  Next Chapter Cognition Donald Norman  Currently with Nielsen Norman group  Previously Professor at UCSD, at Apple, HP, etc....

HUMAN COMPUTER INTERACTION Dr. Bassam Hammo & Dr. Ammar El- Hassan Understanding Users Agenda  Discuss Norman’s views on HCI & design  Next Chapter Cognition Donald Norman  Currently with Nielsen Norman group  Previously Professor at UCSD, at Apple, HP, etc. Material drawn from Norman’s book “The Psychology of Everyday Things" The Psychology of Everyday Things  “Well designed objects are easy to interpret and understand. They contain visible clues to their operation. Poorly designed objects can sometimes be difficult and frustrating to use. They provide no clues – or sometimes false clues.” -- Donald A. Norman Material drawn from Norman’s book “The Psychology of Everyday Things" Daily Challenges  How many people can use all the functionality in their ◦ VCRs & DVD players? ◦ Digital watches? ◦ Copy machines? ◦ Washers & dryers? ◦ Stereo systems? ◦ Cell phones? Typical Frustration What happens when you get frustrated? Fun Examples “Hit any key to continue”  I do not have an “any” key on my keyboard, do you?  This instruction is not correct - try ◦ shift ◦ caps lock ◦ control ◦ print screen Fun Examples Doors Push or Pull? Which side? Push or Pull? Can only push, side Which side? of push is clearly visible Fun Examples Phones How do you - transfer a call - change volume - store a number - etc. Psychology of Everyday Things  Many so-called human errors and “machine misuse” are actually errors in design  Designers help things work by providing a good conceptual model  Designers decide on a range of users as the design audience  But design is difficult for a variety of reasons that go beyond design Two Lessons Lesson 1  Most failures of human-machine system are due to poor designs that do not recognize peoples’ capabilities and limitations  This leads to apparent machine misuse and “human error” Lesson 2  Good design always accounts for human capabilities. Lost Sales  People return products as “broken” when often they simply are not being used correctly.  People return products when they are missing” a feature as in their previous unit. While sometimes true, sometimes the feature is there, it’s that the controls have been changed or moved. Important Design Principles  Affordances  Visibility  Constraints  Mapping  Feedback  Consistency Affordances  The perceived and actual properties of an object that determine how it could possible be used  Appearance indicates how the object should be used  chair for sitting  table for placing things on  knobs for turning  slots for inserting things into  buttons for pushing  computers for ???  Complex things may need explaining, but simple things should not ◦ when simple things need pictures, labels, instructions, then the design has failed! Affordance vs Mappings  Affordances are what an object/product/site can do. Perceived affordances are what we think it can do, which may be correct or incorrect.  The way to make sure the affordances are clear (that is, the perceived affordances match the real affordances) is to use signifiers, which are signs indicating what you can do. Affordance vs Mappings  In the context of Human-Computer Interaction, mappings connect elements of computing artefacts to the real world.  They are the link between what you want to do and what is perceived possible. It is the relationship between moving a control, and the results in the real world. Visibility  Visibility ◦ “The correct parts must be visible, and they must convey the correct message.” ◦ Should indicate:  only necessary things  what parts operate and how  mapping between intended actions and actual operations  crucial distinctions  visibility of the effects – Feedback, BTW Visibility  When functionality is hidden, problems in use occur, e.g., when number of functions is greater than number of controls – Tesla!  When capabilities are visible, it does not require memory of how to use ◦ Remind person how to use something Constraints  Physical constraints ◦ physical characteristics that limit the functionality of an object ◦ limitations of the actions possible perceived from object’s appearance ◦ provides people with a range of usage possibilities Simple Example (I) Electric plugs What if both sides were “big” and you had to remember which side the “small” one went into? Simple Example (II)  Bathroom faucets ◦ Two functions  Hot/cold  Pressure Bathroom Faucets 1 Can you figure out how to use it? Are functions clear and independent? Bathroom Faucets 2 Can you figure out how to use it? Are functions clear and independent? Bathroom Faucets 3 Can you figure out how to use it? Are functions clear and independent? Mappings  Mappings ◦ A relationship between two things  A relationship between what you want to do and what appears possible  Relationship between controls and their effect on the system Stove Example Which controls which? Remote Example Vs Samsung Curved Remote Feedback  “Sending back to the user information about what action has actually been done and what result has been accomplished” Causality – 3 Timelapse bands  The thing that happens right after an action is assumed by people to be caused by that action ◦ Interpretation of “feedback” False causality ◦ incorrect effect  starting up an unfamiliar application just as computer crashes  causes “superstitious” behaviors ◦ invisible effect  command with no apparent result often re-entered repeatedly  e.g., mouse click to raise menu on unresponsive system Other Clues …  Transfer of learning effects  Population stereotypes / cultural standards Transfer effects  People transfer their learning/expectations of similar objects to the current objects ◦ positive transfer: previous learning apply to new situation ◦ negative transfer: previous learning conflict with new situation Population stereotypes  People learn stereotypes that work in a certain way  red means danger  green means safe ◦ but stereotypes vary in different cultures!  light switches  America: down is off  Britain: down is on ◦ Faucets  America: anti-clockwise on  Britain: anti-clockwise off ◦ ignoring/changing stereotypes?  home handyman: light switches installed upside down  calculators vs. phone number pads: which should computer keypads follow? Cultural Associations Car Model Names  Because a trashcan in Thailand may look like this: a Thai user is likely to be confused by this image popular in Apple interfaces:  Sun found their email icon problematic for some American urban dwellers who are unfamiliar with rural mail boxes. Designing for People  Norman’s 2 main principles ◦ Provide a good conceptual model ◦ Make things visible Conceptual Model  An understanding of how something works that allows us to predict the effects of our actions  Describes the ways in which systems are understood by different people  Often based on users previous experiences  Clues can also be provided from affordances, constraints, and mappings Conceptual model  People have “mental models” of how things work  Conceptual models built from: ◦ Affordances ◦ Causality ◦ Constraints ◦ Mapping ◦ Population stereotypes/cultural standards ◦ Instructions ◦ Interactions ◦ Familiarity with similar devices (positive transfer)  Models may be wrong, particularly if above attributes are misleading  Models allow people to mentally simulate operation of a device Two Guidelines for Design 1. Provide a good conceptual model  allows user to predict the effects of our actions  problem: ◦ designer’s conceptual model communicated to user through system image incl: appearance, written instructions, system behavior through interaction, transfer, idioms and stereotypes ◦ if system image does not make model clear and consistent, user will develop wrong conceptual model Two Guidelines for Design 2. Make things visible  relations between user’s intentions, required actions, and results are ◦ Sensible ◦ non arbitrary ◦ Meaningful  visible affordances, mappings, and constraints  use visible cultural idioms  reminds person of what can be done and how to do it Conceptual Model Fundamental Design Goal Ultimate goal: Use should be driven by the design, hopefully without any need for words or symbols, and definitely without any need for trial and error. Can this be done for all users and all tasks? Who Do You Design for? The person of medium height is able to see the mirror. The taller person must slouch. The shorter person is out of luck. Who Do You Design for? The person of medium height is easily able to walk through. The taller person better slouch. The shorter person is easily able to walk through. Who Do You Design for? Who do we Design for? People are different  It is rarely possible to accommodate all people perfectly ◦ design often a compromise  e.g. ceiling height: 8'  but tallest man: 8' 11"!  Rule of thumb: ◦ design should cater for 95% of audience (i.e. for 5th or 95th percentile)  but means 5% of population may be (seriously!) compromised ◦ designing specifically for the average is generally a mistake  may exclude half the audience  Examples: ◦ cars and height: headroom, seat size ◦ computers and visibility:  font size, line thickness, color for color blind people? Why design is hard (I)  Over the last century ◦ the number of things to control has increased dramatically  car radio: AM, FM1, FM2, 5 pre-sets, station selection, balance, fader, bass, treble, distance, mono/stereo, Dolby, tape/CD eject, fast forward and reverse, etc (while driving at night!) ◦ display is increasingly artificial  red lights in car indicate problems vs. flames for fire ◦ feedback more complex, subtle, and less natural  is your digital watch alarm on and set correctly? ◦ errors increasing serious and/or costly  airplane crashes, losing days of work... Litigation Why design is hard (II)  Marketplace pressures ◦ adding functionality (complexity) now easy and cheap  computers, cell phones, cameras, etc. ◦ adding controls/feedback expensive  physical buttons, LEDs, display resolution  menus, descriptions, feedback consume screen real estate ◦ design usually requires several iterations before success  product can be pulled if not immediately successful ◦ people often consider cost and/or appearance over human factors design ◦ design is an art - usability testing does not replace design! Individual Differences  Designers are not representative of the user population for whom they are designing  do not expect users to think or act like you  People vary in both physical attributes and mental/cognitive attributes What is your initial impression of this item? Comfort /Learning the Technology  People are often intimidated by technology  Users are often afraid of breaking the system or losing data  Given these two issues, how do people learn the technology? Examples: ◦ Support rapid, incremental, reversible actions ◦ do not use dialogs to report normalcy ◦ If it’s worth asking the user, it’s worth storing their choices  Implemented through “Direct Manipulation”, or at least “Undo”  Encourages experimentation, increases comfort Try and Try Again  Norman thinks that it often takes 5 or 6 tries to get something “right”  Simply may not have that luxury in a competitive business environment What You Now Know  There are several basic cognitive principles to be aware of while designing interfaces: ◦ Affordances => Visibility ◦ Constraints ◦ Mappings ◦ Causality => Feedback ◦ Transfer effects ◦ Consistency / Cultural standards ◦ Mental Models / Conceptual Models ◦ Comfort => Undo