Spring 2008 6.831 User Interface Design and Implementation 1Lecture 22: Heuristic Evaluation UI Hall of Fame or Shame?Spring 2008 6.831 User Interface Design and Implementation 2 From Shauni Deshmukh: “Kayak.com is a website that allows people to search for flights. In my mind, this site stands out from others (Travelocity, Expedia, etc.) because it makes searching for the right flight easier and faster. Kayak aggregates search results from several different sites and therefore the user gets a large amount of information all in one place.” Let’s think about Kayak with respect to all our design principles: - learnability - simplicity - visibility - user control - error handling - efficiency - graphic design Today’s Topics• Heuristic evaluationSpring 2008 6.831 User Interface Design and Implementation 3 Today’s lecture covers another technique for finding usability problems in user interfaces: heuristic evaluation. Heuristic evaluation is an inspection technique, not unlike doing a code review to find bugs in software. Usability Guidelines (“Heuristics”)• Plenty to choose from– Nielsen’s 10 principles– Norman’s rules from Design of Everyday Things– Tognazzini’s 16 principles– Shneiderman’s 8 golden rules• Help designers choose design alternatives• Help evaluators find problems in interfaces (“heuristic evaluation”)Spring 2008 6.831 User Interface Design and Implementation 4 To understand the technique, we should start by defining what we mean by heuristic. Heuristics, or usability guidelines, are rules that distill out the principles of effective user interfaces. There are plenty of sets of guidelines to choose from – sometimes it seems like every usability researcher has their own set of heuristics. Most of these guidelines overlap in important ways, however. The experts don’t disagree about what constitutes good UI. They just disagree about how to organize what we know into a small set of operational rules. Heuristics can be used in two ways: during design, to help you choose among alternative designs; and during heuristic evaluation, to find and justify problems in interfaces. 6.831 Principles• Learnability• Simplicity• Visibility• User control & freedom•Errors• Efficiency• Graphic designSpring 2008 6.831 User Interface Design and Implementation 5 To help relate these heuristics to what you already know, here are the high-level principles that have organized our lectures. L = Learnability S = Simplicity V = Visibility UC = User control & freedom ER = Error handling EF = Efficiency GD = Graphic design Nielsen Heuristics1. Match the real world (L)2. Consistency & standards (L)3. Help & documentation (L)4. User control & freedom (UC)5. Visibility of system status (V)6. Flexibility & efficiency (EF)7. Error prevention (ER)8. Recognition, not recall (ER)9. Error reporting, diagnosis, and recovery (ER)10.Aesthetic & minimalist design (GD, S)Spring 2008 6.831 User Interface Design and Implementation 6 Jakob Nielsen, who invented the technique we’re talking about, has 10 heuristics, which can be found on his web site. (An older version of the same heuristics, with different names but similar content, can be found in his Usability Engineering book, one of the recommended books for this course.) We’ve talked about all of these in previous design principles lectures (the lecture is marked by a letter, e.g. L for Learnability). Norman Principles• Affordances (L)• Natural mapping (L)• Visibility (V)• Feedback (V)Spring 2008 6.831 User Interface Design and Implementation 7 We’ve also talked about some design guidelines proposed by Don Norman: visibility, affordances, natural mapping, and feedback. Tog’s 16 Principles1. Anticipation (EF)2. Autonomy (UC)3. Color blindness (GD)4. Consistency (L)5. Defaults (EF)6. Efficiency (EF)7. Explorable interfaces (UC)8. Fitts’s Law (EF)9. Human interface objects (L)Spring 2008 6.831 User Interface Design and Implementation 810.Latency reduction (V)11. Learnability (L)12.Metaphors (L)13. Protect users’work (ER)14. Readability (GD)15. Track state (EF)16. Visible navigation (V) Another good list is Tog’s First Principles, 16 principles from Bruce Tognazzini (http://www.asktog.com/basics/firstPrinciples.html). We’ve seen most of these in previous lectures. Here are the ones we haven’t discussed (as such): Autonomy means user is in control. Human interface objects is another way of saying direct manipulation: onscreen objects should continuously perceivable, and manipulable by physical actions. Latency reduction means minimize response time and give appropriate feedback for slow operations. Shneiderman’s 8 Golden Rules1. Consistency (L)2. Shortcuts (EF)3. Feedback (V)4. Dialog closure (V)5. Simple error handling (ER)6. Reversible actions (UC)7. Put user in control (UC)8. Reduce short-term memory load (ER)Spring 2008 6.831 User Interface Design and Implementation 9 Finally we have Shneiderman’s 8 Golden Rules of UI design, which include most of the principles we’ve already discussed. Heuristic Evaluation• Performed by an expert•Steps– Inspect UI thoroughly– Compare UI against heuristics– List usability problems– Explain & justify each problem with heuristicsSpring 2008 6.831 User Interface Design and Implementation 10 Heuristic evaluation is a usability inspection process originally invented by Nielsen. Nielsen has done a number of studies to evaluate its effectiveness. Those studies have shown that heuristic evaluation’s cost-benefit ratio is quite favorable; the cost per problem of finding usability problems in an interface is generally cheaper than alternative methods. Heuristic evaluation is an inspection method. It is performed by a usability expert – someone who knows and understands the heuristics we’ve just discussed, and has used and thought about lots of interfaces. The basic steps are simple: the evaluator inspects the user interface thoroughly, judges the interface on the basis of the heuristics we’ve just discussed, and makes a list of the usability problems found – the ways in which individual elements of the interface deviate from the usability heuristics. The Hall of Fame and Hall of Shame discussions we have at the beginning of each class are informal heuristic evaluations. In particular, if you look back at previous lecture notes, you’ll see that many of the usability problems identified in the
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