COAP:COAP-3150 - week 6

Interaction styles

• HCI interaction styles - based on Shneiderman

Usability testing

Heuristics and quick tests

The 5 second rule

Upon landing on a homepage a user should be able to figure out in 5 seconds - The 5 second rule

• What is it about?
• Do I care?
• Is it trustworthy?
• How do I participate?
• Is it newsworthy?

Ten Usability Heuristics by Jakob Nielsen

Reduced to five in Usability 101.

• Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
• Efficiency: Once users have learned the design, how quickly can they perform tasks?
• Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
• Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
• Satisfaction: How pleasant is it to use the design?

Borrowing from Davis' Technology acceptance model, Nielsen defines useful web design as

• Utility = whether it provides the features you need.
• Usability = how easy & pleasant these features are to use.
• Useful = usability + utility.

Ergonomic criteria for evaluating interfaces and interactions

Bastien and Scapin (1997), through studies conducted, showed usability to be based on criteria that place significantly les importance on a systems information efficiency than Nielsen. Their criteria for ergonomics of interfaces focus strictly on the system's usability (manageability):

• Guidance: incite, orient user, group information (proximity, repetition), immediate feedback, legibility
• User workload: diminish cognitive effort for user, be brief, minimal actions, reduce information density
• User explicit control: allow users explicit control of their actions
• Adaptability: flexible, environment adjusts to accommodate user preferences
• Error management: help avoid or allow for the correction of errors, meaningful error messages
• Consistency: keep interface consistent for particular context, change for change of context.
• Significance of codes: coherence between signs and the object or action to which they refer
• Compatibility: content and actions are compatible with the habits and practices of target public

Related pages

• Usability
• Interaction design
• Design and usability methods and techniques
• User interaction and user interface design - definitions and distinction

Generating authentic user tasks

See Scenario-based usability engineering

Designing the test

Three basic steps to usability testing from Nielsen's Usability 101:

• Get hold of some representative users, such as customers for an e-commerce site or employees for an intranet (in the latter case, they should work outside your department).
• Ask the users to perform representative tasks with the design.
• Observe what the users do, where they succeed, and where they have difficulties with the user interface.
• Shut up and let the users do the talking.

• Why You Only Need to Test with 5 Users - 5 users represent 80% of problems

Examples

Bad usability in (web) design

• webpagesthatsuck.com
• bad designs
• Operating system interface design between 1981-2009

Designing interaction

Webforms (self-study)

See HTML forms tutorial

Javascript (self-study)

See and Javascript tutorial - basics

Assignment 8 - Functional prototype

Described in week 6 Learning module

Links

• Usability Testing Toolkit: Resources, Articles, and Techniques

References

• NIELSEN, J., (1993) Usability engineering. Boston, Academic Press.
• SCAPIN, D.L. and BASTIEN, J.M.C. (1997). Ergonomic criteria for evaluating the ergonomic quality of interactive systems. Behavior & Information Technology, 1997, 17 (4/5), 220-231.
• SHNEIDERMAN, B. (1992). Designing the user interface : strategies for effective human-Computer-Interaction. (Chap 3, 4 and 5). 2nd ed., Addison-Whesley Publishing Company.