Transcript N-Ch 4
Norman Chapter 4 Knowing What To Do Jeff Offutt http://www.cs.gmu.edu/~offutt/ SWE 205 Software Usability and Design People Expect Simplicity • When a task is simple, people expect the device to be simple – Making a phone call is simple – Devices that do a lot of things are harder • Multi-purpose devices – The most common action should be the easiest to find – It is okay for rare actions to be harder • When we encounter a new device, either : – We transfer knowledge of how to use a similar device or – We seek instructions 1-Jul-16 © Jeff Offutt, 2010-2015 2 Syntactic Signals • The UI design must explicitly indicate what should be done – Physical or syntactic constraints limit our actions – Affordances of controls—that is, the controls look familiar • Down arrows look like drop downs • “B” looks like bold face • If the UI design matches the user’s mental model and offers good controls, users will not need help 1-Jul-16 © Jeff Offutt, 2010-2015 3 Doors & Switches • Dozens of ways to open doors • A sign on a door that tells us how to open it is a very short instruction manual – If a simple device needs an instruction manual, the UI is a failure – Doors on the Paris subway do not open automatically • Switches have two basic problems 1. Which switch controls which function (grouping) ? 2. Which switch controls which device (mapping) ? • My childhood home had 3 switches for 3 kitchen lights – Despite living there for 49 years, NOBODY remembered which switch controlled which light ! 1-Jul-16 © Jeff Offutt, 2010-2015 4 Door Opening Confusion A push bar for an emergency door … This is much clearer But which side to push ? 1-Jul-16 © Jeff Offutt, 2010-2015 When under stress, people revert to stereotypes 5 My Very Own “Norman Door” How do you open it? 1-Jul-16 © Jeff Offutt, 2010-2015 6 Light Switch Device Confusion Light arrangement on the ceiling Light switch arrangement one Light switch arrangement two Kitchen Porch 1-Jul-16 © Jeff Offutt, 2010-2015 7 Visibility and Feedback Visibility Make relevant parts visible Feedback Give each action an immediate and obvious effect 1-Jul-16 © Jeff Offutt, 2010-2015 8 Summary : Good Displays • This book was written in 1988 … how about the three suggestions he gave for adding visibility ? 1. Display the song titles for CDs • • 2012 : Nope 2015 : Sometimes 2. Display the names of TV programs • 2010 : Yes 3. Let microwaves read cooking instructions from labels • 2012 : Nope • * sigh * … I hoped Norman’s book would be a bit more out of date … 1-Jul-16 © Jeff Offutt, 2010-2015 9