2. P3
Code Submission: Submit your code, binaries and assets as a zip file on Piazza by 5pm today. This is the code that you will use to demo in your tutorial. Demos: Your demo will happen for 10 minutes in your tutorial. Remember that each member of your team needs to present. 5 minute question session: you will be evaluated on your ability to handle questions.

3. P4 - Final Report & Presentation
Already posted
Reflect back on your work in this project.
» Major discoveries
» Major design decisions & rationale
» Discoveries from heuristic evaluation
» Next steps in subsequent iteration
There is an outline -- follow it!

4. Fitts’ Law and Applications
CPSC 481: HCI I
Winter 2014
Anthony Tang

5. Learning Objectives By the end of the lecture, you should be able to:
» Describe the original Fitts' law experiments
» Provide an interpretation for Fitt's law
» Identify two ways that Fitts' Law can be used in interaction design
» Critique visual designs using Fitts' Law

6. Fitts’ Law: The Punchline
Big targets are easier to hit than small targets + Close targets are easier to hit than far targets

7. Paul Fitts’ Experiments
Reciprocal tapping task
Varying the distance between these plates
Varying also the width of the target area on the plates
Goal: understand the nature of worker effeciency, sucha s in production line and assembly task

8. In GUIs, too!
Model of human movement
Predicts time for rapid, aimed movemnet
Example: a mouse pointer over a button
Originally, one-dimensional movement, extended by varios researchers

9. Fitts’ Law as an equation
MT = movement time A = amplitude (distance to target) W = width (width of target) a,b = empirically determined constants

10. Fitts’ Law as an equation
MT = movement time A = amplitude (distance to target) W = width (width of target) a,b = empirically determined constants ID = “index of difficulty” in bits IP = 1/b = “index of performance” – bits/s
How to get a and b? let’s actually run a small experiment
What is a: how much time it takes you to realize where you need to go, how much time it takes to click
What is b: device-specific characteristics (e.g. using your arm to move, vs. using your leg to move, vs. using a mouse, vs. using a joystick, vs. using a stylus)

11. Fitts’ Law
Allows us to design navigation Allows us to evaluate input devices/techniques

12. Think about the targets on this screen
Think about the targets here
Just list a few of the targets
Which are big?
Which are easy to click?

13. Discussion Questions
Microsoft Toolbars offer the user the option of displaying a label below each tool. Give two reasons why labeled tools can be access faster. (Assume the user knows the tools, and does not need the labels to identify the tool.)
The label becomes the target, and so it is bigger.
When labels are not used, the tool icons crowd together

14. Discussion Questions
Assume you will this layout of buttons on the left edge of the screen. Without changing the size of these icons, what can you do to decrease the amount of time it takes to access the tools?
Change the array to 1x12
Ensure you can click the pixels to the left of the button, too!!

15. Discussion Questions
Explain why a Macintosh pull-down menu can be accessed at least five times faster than a typical Windows pull-down menu. Suggest why Microsoft made the decision to make their pull-downs the way they did.
Screen edge is a “mile-high” target in OS X – this means that the menus are super easy to hit, and very tall targets
One reason why MS did it is maybe b/c it’s closer to the target? Another potential reason: Mac patented the menu bar
This breaks when there is a monitor on top of another monitor

16. Swiftpoint

17. Comparing TouchPad to Swiftpoint

18. BubbleCursor
Challenge: make it so that it’s easier to click on targets Original approach: use an area cursor BubbleCursor approach: use a dynamically resizing area cursor

19. EdgeWrite
Use the corners of a boundary area for super fast text entry.

20. EdgeWrite Contexts..

21. Fitts’ Law and Touch Interfaces
Compact placement of icons
Scrollbar annoyingness
What do we do now?
Discoverability?

22. Fitts’ Law and Touch Interfaces
Notice the closeness of the comment and thumbs up fields
Think about a mouse: easy to control
Your finger: pretty honking

23. Learning Objectives You should now be able to:
» Describe the original Fitts' law experiments
» Provide an interpretation for Fitt's law
» Identify two ways that Fitts' Law can be used in interaction design
» Critique visual designs using Fitts' Law