Measuring the effective parameters of steering motions

ABSTRACT

The steering law model describes pointing device motion through constrained paths. Previous uses of the model are deficient because they are built using only error-free responses, ignoring altogether the path of the cursor. We correct this by proposing and validating a technique to include spatial variability, including errors. The technique is a variant of the well-known "effective target width" used in Fitts' law models. An experiment designed to test our technique demonstrates the improvement: Correlations are consistently higher when spatial variability is included in building the model. Suggestions to aid further development of the steering law model are included.

REFERENCES

• 1: Johnny Accot , Shumin Zhai, Beyond Fitts' law: models for trajectory-based HCI tasks, Proceedings of the SIGCHI conference on Human factors in computing systems, p.295-302, March 22-27, 1997, Atlanta, Georgia, United States [doi>10.1145/258549.258760]
• 2: Johnny Accot , Shumin Zhai, Scale effects in steering law tasks, Proceedings of the SIGCHI conference on Human factors in computing systems, p.1-8, March 2001, Seattle, Washington, United States [doi>10.1145/365024.365027]
• 3: Johnny Accot , Shumin Zhai, More than dotting the i's --- foundations for crossing-based interfaces, Proceedings of the SIGCHI conference on Human factors in computing systems: Changing our world, changing ourselves, April 20-25, 2002, Minneapolis, Minnesota, USA [doi>10.1145/503376.503390]
• 4: Johnny Accot , Shumin Zhai, Performance evaluation of input devices in trajectory-based tasks: an application of the steering law, Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit, p.466-472, May 15-20, 1999, Pittsburgh, Pennsylvania, United States [doi>10.1145/302979.303133]
• 5: Fitts, P, M. The information capacity of the human motor system in controlling the amplitude of movement, Journal of Experimental Psychology 47, 1954, 381--391.
• 6: MacKenzie, I. S. Fitts' law as a research and design tool in human-computer interaction. Human Computer Interaction 7, 1992, 91--139.

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.1 MODELS AND PRINCIPLES
      H.1.2 User/Machine Systems
          Subjects: Human factors

Additional Classification:
  H. Information Systems
  H.1 MODELS AND PRINCIPLES
      H.1.2 User/Machine Systems
          Subjects: Human information processing

General Terms:
Human Factors

Keywords:
Fitts' law, effective width, error rate, steering law