Introduction to Introduction to Computer Input Devices Computer Input Devices and Their Evaluation and Their Evaluation Shumin Zhai Shumin Zhai IBM Almaden Research Center IBM Almaden Research Center
Mar 30, 2015
Introduction to Computer Input Introduction to Computer Input Devices and Their EvaluationDevices and Their Evaluation
Shumin ZhaiShumin Zhai
IBM Almaden Research CenterIBM Almaden Research Center
First Mouse (Douglas Engelbart and First Mouse (Douglas Engelbart and William English, 1964)William English, 1964)
First Mouse Patent (Engelbart)First Mouse Patent (Engelbart)
"A Research Center for Augmenting Human Intellect," "A Research Center for Augmenting Human Intellect," Douglas C. Engelbart, and William K. English, Douglas C. Engelbart, and William K. English, Proc. Proc. 1968 Fall Joint Computer Conference1968 Fall Joint Computer Conference
A Variety of Input DevicesA Variety of Input Devices
MouseMouse StylusStylus TouchscreenTouchscreen TouchpadTouchpad JoystickJoystick ......
Performance EvaluationPerformance Evaluation ““I like it!” / “It is cool!” is not enoughI like it!” / “It is cool!” is not enough
• ““Perception is not always reality”Perception is not always reality”• Conscious articulation is not always behavior Conscious articulation is not always behavior
(describe how to ride a bike)(describe how to ride a bike)
Individual differencesIndividual differences Making HCI an empirical (good) scienceMaking HCI an empirical (good) science
Iterative DesignIterative Design
Observation/ idea
Design/implementation
Product/Knowledge
PerformanceEvaluation
• Evaluation for insights• Evaluator vs. designer
QualitativeQualitative Analysis Analysis
TouchscreenTouchscreen• ProsPros• ConsCons
Stylus / light penStylus / light pen• ProsPros• ConsCons
Quantitative Performance EvaluationQuantitative Performance Evaluation
What to measure? What to measure? • Depending on the task / application scenarioDepending on the task / application scenario
Common measuresCommon measures• Trial completion timeTrial completion time• Error rateError rate• Learning speedLearning speed• Comfort / fatigueComfort / fatigue• etc.etc.
Real task: Interacting with WIMP interfaceReal task: Interacting with WIMP interface Experimental task: target acquisition Experimental task: target acquisition
• abstract, elemental, essentialabstract, elemental, essential
Performance measures: time, error ratePerformance measures: time, error rate
Pointing Device EvaluationPointing Device Evaluation
Fitts’ law Fitts’ law ((Paul Fitts, 1954)Paul Fitts, 1954)
MT MT == a a ++ b b loglog22( +1)( +1)DDWW
IDID
DD
WW
1/b - Index of Performance, Throughput, Bandwidth
Fitts’ lawFitts’ law
““The information capacity of the human The information capacity of the human motor system in controlling the amplitude of motor system in controlling the amplitude of movement”,movement”,
Journal of Experimental PsychologyJournal of Experimental Psychology, , vol 47, 381-391vol 47, 381-391
ID (bits)log2(A/W+1)
Time (sec)
***
**
***
**
***
**
***
**
Experimental DesignExperimental Design
Fairness for the given taskFairness for the given task Wide enough ID combinationsWide enough ID combinations
• W’s: from character size (10) to icon (30 W’s: from character size (10) to icon (30 pixel)pixel)
• A’s: from short (60) to cross screen (800)A’s: from short (60) to cross screen (800) Multiple individuals/subjectsMultiple individuals/subjects Balancing ordersBalancing orders Statistical analysisStatistical analysis Controlling error (about 5%)Controlling error (about 5%)
A BB A
A B CB C AC A B
Task modeling for evaluationTask modeling for evaluation
Bring task modeling to device Bring task modeling to device evaluationevaluation• Card, English, Burr, 1978Card, English, Burr, 1978
“Evaluation of mouse, rate controlled isometric “Evaluation of mouse, rate controlled isometric joystick, step keys and text keys for text selection joystick, step keys and text keys for text selection on a CRT”, on a CRT”,
ErgonomicsErgonomics, vol. 21, , vol. 21, 601-613601-613
Beyond Fitts’ lawBeyond Fitts’ law
Hick’s lawHick’s law Key stroke modelKey stroke model Control theoretic modelingControl theoretic modeling Limitations to Fitts law: pointing onlyLimitations to Fitts law: pointing only
Trajectory-based tasksTrajectory-based tasks Example: hierarchical menusExample: hierarchical menus Is there a “law” to Steering?Is there a “law” to Steering?
Thought experiment...Thought experiment...
2 goals passing2 goals passingIDID = log = log22 ( +1) ( +1)
3 goals passing3 goals passingIDID = 2 log = 2 log22 ( +1) ( +1)
N+1 goals passingN+1 goals passingIDID = = NN log log22 ( +1) ( +1)
goals passinggoals passingIDID = ? = ?
AAWW
AA
2W2W
AANWNW
AA
A/2A/2
A/NA/N
A/2A/2
A/NA/N A/NA/N
WW
AAWW
AA
WW
““Steering law”Steering law”
Steering law (Accot and Zhai 1997)Steering law (Accot and Zhai 1997)• ““Beyond Fitts’ law: Modeling trajectory based HCI tasks”, Beyond Fitts’ law: Modeling trajectory based HCI tasks”,
Proc of CHI’97Proc of CHI’97
dxdxW(x)W(x)
IDIDCC = =
CC
TTCC = a + b ID = a + b IDCC
ResultsResults
AA
WW
Device comparison in steeringDevice comparison in steering tasks tasks(Accot & Zhai, CHI’99)(Accot & Zhai, CHI’99)
Steering Index of Difficulty
Time
5 10 15 20 25 30
Trackball
Touchpad
Trackpoint
MouseStylus
Conferences and Journals Conferences and Journals
CHI: ACM Conference on Human Factors in CHI: ACM Conference on Human Factors in Computing SystemsComputing Systems
INTERACT: IFIP Conference on Human Computer INTERACT: IFIP Conference on Human Computer InteractionInteraction
UIST: ACM Symposium on User Interface Software and UIST: ACM Symposium on User Interface Software and TechnologyTechnology
HFES: Human Factors and Ergonomics Annual HFES: Human Factors and Ergonomics Annual MeetingMeeting
ACM Transactions on Computer Human Interaction ACM Transactions on Computer Human Interaction (TOCHI)(TOCHI)
Lab Assignment Lab Assignment Measure Fitts’ law index of performance with bare Measure Fitts’ law index of performance with bare
hand on paperhand on paper Measure any two devices using Fitts’ law with the Measure any two devices using Fitts’ law with the
Almaden Program Almaden Program Compare performance of the two devicesCompare performance of the two devices Compare devices with bare handCompare devices with bare hand Discuss the validity/benefits of Fitts’ law in your Discuss the validity/benefits of Fitts’ law in your
study.study. Discuss pros and cons of the devices: suggest Discuss pros and cons of the devices: suggest
improvements or new designsimprovements or new designs