1. Class Presentation An Ordering of Secondary Task Display Attributes David Tessendorf, Christa Chewar, Ali Ndiwalana, Jon Pryor CS5984: Information Visualization Show me the data!

2. Presentation Overview Background Problem Statement Experimental design –Attribute encoding –Latin square –Demo Results –General Results –Results by Question Type –Results by Acceptable Degradation Conclusions –Inferences –Further work Questions

3. Background Cleveland and McGill’s ordering of graph attributes Limited research about secondary tasks in a dual task system Position, common scale Position, nonaligned scale Length Direction Angle Area Volume Curvature Shading Color saturation 10 5 0 10 5 0 10 5 0

4. Research Objective Does it apply to computer displays? Does it apply to communication of secondary tasks? 10 5 0 10 5 0 10 5 0 Cleveland and McGill’s experiments establish an ordering of perceptual tasks for print-based media in the FOCUS

5. Graphs and scales used to test attribute effectiveness Three different questions are used on each graph –identify min/max value –count matched comparison –determine ratio Questions and answers are constant throughout all six versions; only the attribute encoding varies –“what is the minimum value?” -- Answer does not vary Experimental Design (Attribute Encoding) 10 5 0

6. Experimental Design (Latin Square) 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 10 5 0 Each block = 3 rounds, one for each question type Version 1 23456 With Game No Game With Game Always: 9 dual-task rounds 9 focus rounds 6 rounds w/ each attribute Same round question regardless of version or attribute Goal: 15 subjects per version 90 total subjects No colorblind

7. Demo

8. p=0.61 p=0.31 p=0.13 p=0.07 p=0.47 p=0.01 Ordering: p=0.00046 p=0.001 p=0.102 p=0.093 General Results

9. Results by Question Type

10. Area: Color: Position: Min/MaxCountRatio

11. Ordering significance p < 0.05 Min/Max Count Ratio Position Color Area Search Task Compare Task

12. Results by Acceptable Degradation Show me the significance!!! Pink & blue lines/points are p-values for cumulated performance data Dark lines are 6th order regression trendlines Demonstrates confidence in attribute relationships

13. Confirmed Cleveland’s ordering in the focus, i.e. position, area, and then color (F(2,277)=7.91, MSE=.409, p=.00046) Empirically extended Cleveland’s ordering to digital display design Established different orderings for search & computation tasks performed as a dual task Established an ordering for the secondary tasks, –3% to 22% degradation = position, color, then area –Past 23% = position then color, uncertain about area Conclusions

14. How do other attributes fit in the ordering? How do color hue differences order? How do multi-attribute encodings order? Differences between male & female? Do real people perform differently? Further Research 10 5 0 10 5 0 10 5 0 ? ? ? 10 5 0 10 5 0?

15. Many thanks to……. Questions….? Dr. Scott McCrickard for his advice and encouragement Jacob Somervell for his advice, encouragement, and use of his highly specialized Tcl/Tk program, which served as our base experimental platform