11 hci - lesson 5.1 heuristic inspection (nielsen’s heuristics) prof. garzotto
Post on 19-Dec-2015
219 views
TRANSCRIPT
11
HCI - Lesson 5.1
Heuristic Inspection (Nielsen’s Heuristics)
Prof. Garzotto
HEURISTIC Evaluation : an INSPECTION METHOD
Invented by J. Nielsen during mid nineties
What to do: One or more expert evaluators (usually from 3 to 5) systematically inspect a system and evaluate its compliance to a set of established guidelines (heuristics)
When: at any time during the development process
Object of evaluation Design documents Prototyper Final product
Nielsen’s Heuristic Evaluation in its inventor’s eyes
Nielsen’s 10 heuristics
Not universally recognized Other practitioners and scholars have defined their own
set of heuristics
1. Visibility of system status2. Match between system and the real world3. User control and freedom4. Consistency and standards5. Error prevention 6. Recognition rather than recall 7. Flexibility and efficiency of use 8. Aesthetic and minimalist design9. Help users recognize, diagnose and recover from errors10. Help and documentation
1. Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
Example: status bar
in web sites: site map, orientation info...
2. Match between system and the real world
The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
ExampleWhat “adds-in” means?
3. User control and freedom
Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Example: e-commerce (ticket on line)
if you do a mistake in your order, avoid to start the selection process again from the beginning – just undo some actions
4. Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Example: this symbol should always mean «close»
5. Error prevention
Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
ExampleIt is frequent in many websites to get to the wrong page – a page you are not intended to go to. Rather that offering the user a back buttom (often, the browser «back») it would have been better to explain the link destination (e.g., through a clear link label) before having the user click the link
6. Recognition rather than recall
Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Esempio: in MS, try to change the keybord language that you have changed by mistake and cause you keys to have a different symbolo (e.g., $ instead of ?): is is clear how to do so or do you have to remember, or get crazy with trial and errors?
7. Flexibility and efficiency of use
Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
Example:web accelators: landmarks
In Windows: crtl+alt+x to replace a sequence of menu items selection
8. Aesthetic and minimalist design
Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
Example: web pages with a long text that needs scrolling;
Marble like background
9. Help users recognize, diagnose and recover from errors
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
Example: user’s mistake in typing error, and related suggestion
10. Help and documentation
Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.
Example:obscure help for setting your keyboard language
References
Nielsen, J., Mack R., Usability Inspection Methods, Wiley 1994.
Nielsen, J., Designing Web Usability, New Riders, 1999.
Jakob Nielsen, www.useit.com
Nielsen’s heuristic (http://www.useit.com/papers/heuristic/heuristic_list.html)
Bruce Tognazzini, www.asktog.com