Web Design 3 HCI Robert ClarksonSoutern Institute of Technology
Human Computer InteractionAttention to human-machine interaction is important, becausepoorly designed human-machine interfaces can lead to manyunexpected problems.A classic example of this is the Three Mile Island accidentwhere investigations concluded that the design of the human-machine interface was at least partially responsible for thedisaster.
Nielsens heuristicsJakob Nielsens heuristics are probably the most-used usabilityheuristics for user interface design. Nielsen developed theheuristics based on work together with Rolf Molich in 1990.The final set of heuristics that are still used today werereleased by Nielsen in 1994.The heuristics as published in Nielsens book UsabilityEngineering
Visibility of system status:The system should always keep users informed about what isgoing on, through appropriate feedback within reasonable time.
Match between system and the realworldThe system should speak the users language, with words,phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, makinginformation appear in a natural and logical order. NOT Arraylist of products Procede to payment gateway
User control and freedomUsers often choose system functions by mistake and will needa clearly marked "emergency exit" to leave the unwanted statewithout having to go through an extended dialogue. Supportundo and redo.Already supported by the browser (to a point), back andforwardEnsure navigation item consistency. The stars didnt move.
Consistency and standardsUsers should not have to wonder whether different words,situations, or actions mean the same thing. Follow platformconventions.Home = Take me to the first page of the site (index.html page)others...
What expected where on the page 1 2 3 4 5http://www.surl.org/usabilitynews/81/webobjects.asp 6 7 8 9 10 link Home Internal Links 11 12 13 14 15 Search Site Advertisements 16 17 18 19 20 Us About 21 22 23 24 25
Error preventionEven better than good error messages is a careful designwhich prevents a problem from occurring in the first place.Either eliminate error-prone conditions or check for them andpresent users with a confirmation option before they commit tothe action.Delete pic0112.jpgAre you sure?!YES NO
Recognition rather than recallMinimize the users memory load by making objects, actions,and options visible. The user should not have to rememberinformation from one part of the dialogue to another.Instructions for use of the system should be visible or easilyretrievable whenever appropriate.
Flexibility and efficiency of useAccelerators—unseen by the novice user—may often speed upthe interaction for the expert user such that the system cancater to both inexperienced and experienced users. Allow usersto tailor frequent actions.For informational websites; quick-links.More relevant when the website is the front-end to a morecomplicated web application.Delete many / Delete all
Aesthetic and minimalist designDialogues should not contain information which is irrelevant orrarely needed. Every extra unit of information in a dialoguecompetes with the relevant units of information and diminishestheir relative visibility.Deleting this file pic0110.jpg would result in the pointer to thefile contents removed from the disk and this then means thatyou wouldnt be able to retrieve them easily without the help ofa computer professional. So are you sure that you want to dothis? YES NOCart, Help, Account"See whats in your Shopping cart""Click here to get help"
Help users recognize, diagnose, andrecover from errorsError messages should be expressed in plain language (nocodes), precisely indicate the problem, and constructivelysuggest a solution.ERROR 0x0323EF02323AB232Enter Phone Number: 0210OOPS32Error, the phone number you entered is not valid please enteronly numbers, and the + symbol.
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Help and documentationEven though it is better if the system can be used withoutdocumentation, it may be necessary to provide help anddocumentation.Any such information should be easy to search, focused on theusers task, list concrete steps to be carried out, and not be toolarge.iPod with a sad face?
SatisficingSatisficing, a portmanteau "combining satisfy with suffice",is adecision-making strategy that attempts to meet criteria foradequacy, rather than to identify an optimal solution. -Wikipedia"A task is to sew a patch onto a pair of jeans. The best needleto do the threading is a 4 inch long needle with a 3 millimetereye. This needle is hidden in a haystack along with 1000 otherneedles varying in size from 1 inch to 6 inches. Satisficingclaims that the first needle that can sew on the patch is the onethat should be used. Spending time searching for that onespecific needle in the haystack is a waste of energy andresources."
Dont make me think (about anything other than the content)Users are going to click on the thing that is nearest to whateverthey are looking for.I need a phone number: i cant see one, so i look at the options,there is a "contact us" link. I click that, then i see the number.Ski field: I want to know how long the Greengates run is. I lookon the coronet peak page, i cant see it. i download the trialmap, i cant find it out there. I give up, and phone NZ ski.The principle of good enough (for evolving systems) favoursquick-and-simple (but potentially extensible) designs overelaborate systems designed by committees.
Testing• Testing one user is 100% better than testing none• Testing is an iterative process• Usability tests always produce useful results• A developer is unsuited to test his or her code