An Investigation of Usability Issues with

Mobile Systems Using a Mobile Eye Tracker

thesis byMarie Norlien

International University in GermanyThesis supervisors:

Prof. Dr. Anthony Jameson & Prof. Dr. Karl Rohr

Outline Introduction Mobile eye tracker Study performed of mobile

systems with a mobile eye tracker Conclusion

What is left to do Acknowledgements

Introduction Mobile systems raise many usability

issues that are not yet well understood. One technique for acquiring data relevant

to these issues is the use of a head-mounted mobile eye tracker

The goals of this thesis are To explore the potential and limitations of an

eye tracker in example studies of one or more typical mobile systems

To contribute some insights into particular usability problems that arise with those systems.

Outline Introduction Mobile eye tracker Study performed of mobile

systems with a mobile eye tracker Conclusion

What is left to do Acknowledgements

Eye tracker ASL Model 501 mobile eye tracker

Worn on users body One camera records the scene the

user is looking at; the other camera records the user’s eye movements

Eye tracker Strengths

Subject is free to move without losing accuracy of calibration

Mobile, within the range of the video receiver Subject can wear glasses

Limitations Subject is wearing many pieces of equipment,

which can be uncomfortable Difficult to calibrate and set up initially Viewing plane is restricted to the view of the

scene camera Cannot use outside

Eye tracker Calibration process

Subjects must be in a fixed position during calibration for the best recording of accurate data

The subject’s eye must not be obstructed by the subject’s eyelid

For example, the eyelid mostly covers the eye when a subject is looking down at a Pocket PC

Eye tracker Potential barriers to accurate calibration

Physical movement of the subject Even slight movement unnoticed by the subject

Excessive overhead light, sunlight, or spot lighting

Inadequate pupil and/or corneal reflection Solutions

Good Calibration methodology Subject should be fixed during calibration

Preventing light with the use of a sun-umbrella, dark walls, and anti-glare calibration surfaces

Outline Introduction Mobile eye tracker Study performed of mobile

systems with a mobile eye tracker Conclusion

What is left to do Acknowledgements

Study performed We analyzed two types of systems

Xybernaut – a small handheld PC with a basic indoor navigation system based on infrared sensors

REAL software developed by the Department of Computer Science, Saarbrücken University

The Compaq Ipaq or Hewlett-Packard (HP) Jornada pocket PC installed with market Global Positioning System (GPS) hardware and software

Study performed Xybernaut

Functionality includes indoor navigation via maps visible to the user from the system screen

The system is configured for a planned route in the Computer Science department at Saarbrücken University

Investigate how a user can manage multi-tasking with a mobile system

Study performed Xybernaut

Xybernaut hardware with REAL software

Study performed Pocket PC

Functionality includes outdoor navigation via a map visible to the user from the pocket PC screen, which the user can manipulate via menus and icons

Compared the functionality of two already existing market GPS navigation systems

World Navigator by Teletype GPS Destinator Personal Navigation System by RACO

Industries Investigate how user-friendly and intuitive

each interface is

Study performed Pocket PC

Compaq Ipaq hardware with

Destinator software

HP Jornada hardware with Teletype software

Study performed Results analyzed

Interview with subject while viewing each video recording

Targeted Questions Event Tables

From the videos, each event was logged systematically (begin & end time)

PERT diagrams From videos and Event Tables the following were

derived 3 diagrams to describe general case behaviors 2 diagrams to describe multi-tasking

Pocket PC evaluation

Study performed Event table example

Study performed Event Tables Summary

Main difference in subjects “Event-driven”

Interested in starting to perform the task Once there was an event, the user adjusted

their plan to solve the task “Plan-driven”

Developing a strategy for each task through map dragging

Having an understanding how they are positioned on the map relative to the environment

Study performed PERT diagram example

Study performed PERT diagrams summary

3 possible answers why users perform tasks sequentially vs. Multi-tasking

The user may find it too hard to perform the actions with the system

The user finds the task so demanding cognitively that the user must focus on one behavior at a time in order to manage the demands

The user needs further information from the system before it makes sense to move forward.

Study performed Pocket PC summary

How the menus should appear and work (4 Usability principles; Dix, et al., 1997)

Familiarity Generalizability Predictability Task Migratability

General comments regarding problems encountered while walking

Outline Introduction Mobile eye tracker Study performed of mobile

systems with a mobile eye tracker Conclusion

What is left to do Acknowledgements

Conclusion To understand the concepts of

multitasking applied to a mobile system There are three basic guidelines

Consider possible uses in the environment of the system in combination with various user behaviors

Consider including the possibility of extraordinary events occurring with the system

Consider situations were the user should not focus their attention on using the system

Jameson, A. (2002). User Multitasking as a Design Challenge for Mobile Multimodal Systems. ITRW on Multi-Modal Dialogue in Mobile Environments

Kloster Irsee, 17-19 June 2002

Conclusion Eye tracking can provide additional

valuable information to a well designed usability study in various structured environments leading to important usability discoveries regarding a given mobile system Despite its limitations User interfaces – PocketPC Navigation

Software Identifies the complexity of user Multi-tasking

while using a mobile system

Conclusion What is left to do

Find the link to Multi-modal systems Struck from thesis title Multi-tasking?

Conclusion Acknowledgements

Thank you to everyone, it would not have been possible without you.

Prof. Dr. Anthony Jameson, DFKI GmbH (German Research Center for Artificial Intelligence)

Prof. Dr. Karl Rohr, International University in Germany

Kerstin Klöckner, DFKI GmbH, Researcher The department of computer science,

Saarbrücken University. Christoph Stahl, Rainer Wasinger, and Christian

Müller

Questions ?