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    Dey alexander usability_training_notes_01 Dey alexander usability_training_notes_01 Document Transcript

    • An introduction to usability Dey Alexander Usability Specialist Monash University dey.alexander@its.monash.edu.au Version 1: July 2004
    • An introduction to usabilityTable of contents Aims of this workshop .............................................................. 3 What is usability? .................................................................... 4 The history of usability ............................................................. 7 Usability problems in our daily lives ............................................. 9 Why usability is important for the web ......................................... 17 Design challenges................................................................... 18 The role of the designer........................................................... 22 Human behaviour on the web .................................................... 27 User-centred design................................................................ 30 Exercises ............................................................................. 33 References........................................................................... 41 Resources ............................................................................ 42 - Page 2 -
    • An introduction to usabilityAims of this workshopThis workshop aims to introduce participants to usability by: • Introducing some common definitions of usability • Identifying some of the experiential components of usability • Providing examples of poor usability from everyday life • Illustrating some basic human factors design principles that affect usability • Providing an overview of user-centred designThe workshop also provides an opportunity for participants to informallyevaluate the usability of several websites. Participants will play the role ofusability test observer and will be able to discuss their findings as a group. - Page 3 -
    • An introduction to usabilityWhat is usability?Consider some of the everyday experiences we have of things that are hardto use: • doors that we try to push open when we should have pulled them • VCRs that we cant program • telephone features, like “divert to voicemail” that we can never remember how to use • photocopiers or fax machines that we simply cannot fathom • computer programs that take forever to understand • websites where it takes ages to find what we are looking for.Some things are a constant struggle to use and we find ourselves repeatedlyhaving to read the manual or ask our colleagues and friends to help us figureout how to get them to work. Others work without problem, and as a result,blend into the background as we go about our daily tasks.The difference between difficult-to-use products or systems and those wedont have to think about using is usability. In other words, usability is easeof use.Jakob Nielsen, a well known advocate of usability, says “usability is themeasure of the quality of the user experience when interacting withsomething”.A formal definitionIn ISO 9241: Ergonomics requirements for office work with visual displayterminals, the International Organisation for Standardisation definesusability as “a measure of the effectiveness, efficiency and satisfaction withwhich specified users can achieve specified goals in a particularenvironment.”The key terms to note in this definition are: • effectiveness: are users able to achieve their goals, fully and in the manner expected, when using a product or system? • efficiency: how much effort is required to use the product or system? • satisfaction: was the user satisfied with the product or system? - Page 4 -
    • An introduction to usabilityBut note also the acknowledgement that systems and products are designedfor: • a specified group of users • to allow users to achieve specific goals • a specific context or environmentThis definition indicates that designers need to be aware of who the users oftheir product or system will be. They must also understand the users’ goalsin using the product or system. And designers must also be aware of thecontext in which users will use the system. There seems to be no place for a“one size fits all” approach.The 5 Es of usabilityWhitney Quesenbery has suggested that a useful way to think about usabilityis to consider the 5 Es of usability: 1. Effective 2. Efficient 3. Engaging 4. Error tolerant 5. Easy to learnEffectiveTo be effective, a product or system must enable the user to complete thetask fully and accurately. • Completeness: was the task fully completed? Were the users goals met? • Accuracy: was the task completed successfully? Did the user get the right or correct result? How well was the work done?EfficientTo be efficient, a product or system must enable the user to complete thetask without too much physical or mental effort. • Speed: was the user able to complete the task quickly? Was the physical effort involved kept to a minimum? • Effort: was the user able to complete the task without too much mental effort? - Page 5 -
    • An introduction to usabilityEngagingTo be engaging, the user must have a good and satisfying experience whenusing the product or system. • Pleasant: did the user have a pleasant experience when working on the task? • Satisfying: was the user satisfied by the way in which the application supported her work?Error tolerantTo be error tolerant, the product or system should minimise the chance oferrors and maximise the user’s ability to recover from any error that mayoccur. • Error prevention: did the user interface help users avoid making errors or did poor design features result in mistakes? When errors occurred, were they minor rather than major? • Error recovery: if the user made an error, how hard did they have to work to recover from it? Was it easy to recognise that an error had occurred and find a way around it?Easy to learnTo be easy to learn, the product or system must be predictable and behaveconsistently. • Predictability: was the user able to work with some certainty because the user interface built on her previous knowledge? • Consistency: was the interface consistent, so that once a user learnt how to use part of the application, they were able to easily learn how to use another part?How “usability” is usedThe term “usability” can be used in a variety of ways. • Usability as an outcome or goal: websites and applications that are usable • Usability as a process: a design methodology or approach • Usability as a set of techniques: usability testing, contextual enquiry, heuristic evaluation. There are many techniques whose aim is to improve usability - Page 6 -
    • An introduction to usability • Usability as a philosophy: where improved usability is a value that motivates the way in which products or systems are developedThe history of usabilityThe concept of usability comes from the field of human factors. Humanfactors—sometimes known as ergonomics—has its roots in psychology andoriginated in the United States military during World War II as a means ofensuring that military staff could use sophisticated weaponry in theconditions of war.Human factors specialists study human beings and their interaction withtheir environment. In particular, human factors is concerned with thecapabilities and limitations of the human mind and body, and how theseaffect interactions with objects and conditions in the environment.Human factors is now a multi-disciplinary field. Mark Chignall, drawing onthe work of Alphonse Chapanis, provides an overview of some of thedisciplines involved include: • Psychology: human sensory capacities, human memory and cognitive processes, and individual differences and their measurement. • Anthropometry: the measurement of the physical features of people as used in the design of seats, chairs, tables, computer consoles, car interiors, aeroplane cockpits, and other workstations. • Environmental medicine: environmental factors and their effects on health and human performance. • Engineering: electrical, mechanical, and chemical characteristics of elements and systems and principles of design, construction and operation of structures, equipment and systems. • Operation research: quantitative methods for the analysis of the performance of manpower, machinery, equipment, and policies in government, military, or commercial spheres; the development of models, such as queueing and allocation models for describing operations • Applied physiology: the vital process and the responses of these vital processes to work, stress, and environmental influences. • Statistics: used for summarising large amounts of data on human measurements and human performance; also used to design sampling schemes and experiments for human studies and performance measurements. - Page 7 -
    • An introduction to usability • Industrial design: design, colour, arrangement, and packaging to combine functionality and an aesthetically satisfying appearance. • Computing: primarily through human-computer interaction which is concerned with human factors relevant to interactions with computers and software applications.The basic goals of human factors work includes: • Meeting a range of basic operational and business objectives including the reduction of errors, improved safety and improved system performance, reduction in loss of time and equipment and increased economy of production. • Objectives bearing on reliability, maintainability, and availability (otherwise known as RMA), and integrated logistic support (also known as ILS). The goals would include increasing reliability, improving maintainability, reducing personnel requirements and reducing training requirements. • Objectives affecting users and operators. Here goals would include improving the working environment, reducing fatigue and physical stress, increasing human comfort, reducing boredom and monotony, increasing ease of use, and increasing user acceptance.Notes___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ - Page 8 -
    • An introduction to usabilityUsability problems in our daily livesLets take a closer look at the design of some ordinary, everyday objectsthat are difficult to use. These examples will help us delve into the causesof usability problems and introduce some design principles from the fieldof human factors.Trapped between the doorsThe first image shows a set of doorsconnecting two buildings. I found the image,and the story associated with it on a websitecalled “Bad Human Factors”, created byMichael Darnell.The story Michael tells is of two people whowere walking from one building to another.They pulled open the first door but could notopen the second. Assuming it was lockedthey returned to the first door, but nowcould not open that one either. For a fewminutes they tried to signal someone tocome and help get them out. After a whilethey realised they needed to push ratherthan pull the doors.The problem arose because both sets of doors have handles on each side.Handles imply or afford pulling. The problem could have been prevented ifflat plates had been used on the side of the door that required a push toopen, leaving handles on the side of the door that opened by pulling.If the designer of the doors had been aware of affordances and constraints,and used them to advantage, the design of the doors would have been moreusable.In his book, The Design of Everyday Things, Donald Norman says thataffordances are the actual or perceived properties of an object thatdetermine how the object could be used. For example: • a chair affords sitting • a button affords pushing • slots afford inserting things into them • knobs afford turningWhen affordances are taken advantage of, users know what to do just bylooking: no picture, label or instruction is required. - Page 9 -
    • An introduction to usabilityConstraints, on the other hand, are properties of an object that limit theway the object can be used in order to make its mode of use obvious.For example, the holes in the handle of a pair of scissors provide constraintsfor use. The small hole suggests only one finger will fit, while the largerhole suggests more than one.Jigsaw puzzles are also an excellent example of using constraints. The shapeof the piece, and the colours and patterns printed on it, provide constraintsfor where it can be placed.In the case of our example doors, the use of flat plates on the sides of thedoors that required pushing would have provided a constraint so that it wasobvious to users that they must push the door.How do you open the fridge?This refrigerator has no handle on the front, butrecessed handles on the side.It was purchased for use in a staff room, and newstaff members commonly had the same problemusing it. After seeing that there were no obvioushandles on the front of the fridge, they wouldlocate the recessed handles on the side and try toopen the fridge. When it didnt budge, they oftenassumed it was sealed tight and so pulled evenharder—some of the stronger ones managing tomove the fridge, but not open the door.What most people failed to notice was that thereare two sets of handles, one on each side. Theywere put there to allow the door to be hinged fromeither side, depending on the layout of the roomwhere the fridge was located.Leaving both sets of handles visible afterinstallation caused confusion. Users were able to,and often did, make mistakes when trying to openthe fridge.This is a good example of the failure to useconstraints to improve usability. While thedesigners intended to provide flexibility byallowing the door to be hinged on the side mostsuitable for its context of use, they failed toprovide constraints to ensure that users onlyattempted to open the door from the appropriateside. - Page 10 -
    • An introduction to usabilityThe case of the mistaken urinal This is a photo of a toilet in a restaurant. Can you guess what the object in the right-hand corner is? The small handmade sign over the top of it (indicated by the arrow) reads "this is a mop sink" suggesting that it has been mistakenly used as a urinal. The problem with this design is to do with its context of use.Men are accustomed to finding urinals in public toilets. Although the designof the mop sink might be perfectly suitable if it were placed in anotherlocation (in a cleaners supply room, for instance), given its location in atoilet, its intended purpose is easily mistaken. In this case, an alternativedesign that made the purpose of the object more obvious, would havesolved the problem.How do I turn on the computer?This is a rather humiliating story that I am prepared to tell to highlightanother important human factors design principle—visibility. Several years ago I started a new job. On my first morning in the office I discovered that I had the choice of using an antiquated old PC or an almost new Macintosh G3. Although Id never used a Mac before, I was more than keen to give it a try, especially as it had a beautiful 21 inch monitor attached. However, I couldnt figure out how to turn it on. There were no obvious buttons on the case, front or back. Risking damage to my yet-to-be established reputation, I knocked on the door of my colleague and asked if he could help me turn the machine on. He couldnt find the ON button either. - Page 11 -
    • An introduction to usabilityEventually, one of us accidentally hit the key on thekeyboard that brought the machine to life. We didntnotice which one it was, and had trouble finding it again asecond time. It turned out to be the apple (or command)key. Incidentally, many Windows users say they have had a similar problemwhen trying to use a Macintosh for the first time.How fast am I travelling?Here is another example of the problem of visibility. Many cars have speedometers and tachometers. There is no standard for placement of these instruments, so the speedo might be on the left side in one car and the right in another.In the case of the picture above, what makes identification of the speedomore difficult is that the same numeric scale is used for both the speedoand the tacho.Using a different scale, and/or making the speedo larger and moreprominent would make the more important of the instruments more visible.Did I send that fax?A few years back our office purchased anew multi-function printer, copier andfax machine that looked just like the oneat right. Id been using it withoutproblems for a few weeks for printingand copying, but my first experience atsending a fax was not a happy one.Id just pressed the send button when Iwas interrupted by a colleague whowalked into the room. We had a shortchat and afterwards, I had no idea ofwhether or not the fax had been sent. I couldnt recall hearing the machinedialling the number and nothing on the LCD display screen indicated whathad gone on.So I tried again. I listened for a dialling sound but there was none, and againthere was no message on the LCD screen (pictured below). - Page 12 -
    • An introduction to usabilityNot easily deterred, I tried a thirdtime. This time I noticed a smallgreen light marked COMM go on(indicated by the black arrow inthe photo). There was still nomessage to indicate that the faxhad been sent, but I was a littlemore confident that it was at leasttrying to send it.It wasn’t until I returned to myoffice a short time later that Iknew the fax had been sent. The person to whom I was trying to send it,telephoned to assure me that they had received it—they had received allthree copies, thank you very much!This incident illustrates another design problem: there was no feedbackabout what the machine was doing. Feedback tells the user about the resultof an action. For example, when we turn a car steering wheel, the carimmediately starts turning. We get immediate feedback about the results ofour action. Some other examples of feedback are: • the tone made when you push numbers on a telephone keypad • the connecting to site name that appears in your web browser status bar when you click on a hyperlink • the clicking sound and flashing dashboard light that shows youve turned on your cars turn indicator.Which knob controls the front left burner? The picture at left is of a four-burner cooktop. The controls for the burner are vertically arranged on the right. I have a cooktop with a similar layout at home. My partner and I often find that we turn on the wrong control, despite the fact that we’ve been using this same cooktop for many years.When I tell this story to other people, theyoften confess to having a similar problem.Now look at the second cooktop. Do youthink people would have the sameproblems identifying the correct knobsusing something designed like this? - Page 13 -
    • An introduction to usabilityThe problem with the first design is poor mapping. Mapping refers to therelationship between things, in this case between the layout of the controlsand the layout of the burners. The relationship is not obvious. The uppercontrol may turn on the top left burner, or the top right. Users would haveto read the labels on the controls to figure it out.In the second design, the layout of the controls matches the layout of theburners, and it is immediately obvious which control operates which burner.No labels are needed.Where designers take advantage of physical analogies or cultural standardsto provide immediate understanding of how things work, Donald Normanrefers to the mapping relationship as “natural mapping”.Steering a car is an example of the use of natural mapping. We turn thesteering wheel clockwise to the right to turn right, and anti-clockwise, or tothe left, to turn left. The mapping relationship is natural and so is easy toremember.The well-trodden path This picture shows a path worn in the grass between two paved paths at the end of a pedestrian crossing. There is a sign erected near the start of the worn path that reads "Landscape Preservation. Please use sidewalks". This is an example of a design (the original location of the paths) and a design solution (the erection of a sign) that both ignore human behaviour. Making a path in the right place instead of wasting money on a sign that is unlikely to motivate a change in human behaviour, wouldhave been a better use of resources.Can’t get a gripThe next photo shows a washbasin in a designer hotel. Thesmooth tap knobs make operatingthe taps very difficult with soapyhands.This design fails partly because ofa failure to realistically considerthe context of use, but alsoindicates a failure to design forhuman behaviour. We don’t all - Page 14 -
    • An introduction to usabilitymanage to get the water pressure and temperature right before we put soapon our hands. Some of us need to make adjustments while were washing.What happens when a heavy doorhas a handle in the middle?The next photo shows a fancy restaurant door. It ismade of heavy-duty glass, and the restaurant isvisible through the top half of the door. But, thehandle is located in the middle of the door, ratherthan on the side. This makes the door very difficultto open for some people because it is not possibleto get good leverage.There is a good reason for the design conventionfor door handles—positioning the handles on oneside makes it easier to open the door.Often, design practices become conventions simplybecause they work well. Breaking designconventions often leads to products or systems thatdont work so well.Here is another example.How do I get water from the tap?This outdoor tap works by lifting the handle. However, it looks like a pump-action device, and so many people thought that they had to pump thehandle in order to get the water to flow.Again, using a more conventional design for the tap would have made iteasier for people to figure out how to use it. - Page 15 -
    • An introduction to usabilityDiscussion:What design problems have you encountered with everyday objects?In your examples, can you identify any design principles that the designerhas not followed?Notes________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ - Page 16 -