Two-part models capture the impact of gain on pointing performance

Garth Shoemaker, Takayuki Tsukitani, Yoshifumi Kitamura, Kellogg S. Booth

Research output: Contribution to journalReview articlepeer-review

29 Citations (Scopus)


We establish that two-part models of pointing performance (Welford's model) describe pointing on a computer display significantly better than traditional one-part models (Fitts's Law). We explore the space of pointing models and describe how independent contributions of movement amplitude and target width to pointing time can be captured in a parameter k. Through a reanalysis of data from related work we demonstrate that one-part formulations are fragile in describing pointing performance, and that this fragility is present for various devices and techniques. We show that this same data can be significantly better described using two-part models. Finally, we demonstrate through further analysis of previous work and new experimental data that k increases linearly with gain. Our primary contribution is the demonstration that Fitts's Law is more limited in applicability than previously appreciated, and that more robust models, such as Welford's formulation, should be adopted in many cases of practical interest.

Original languageEnglish
Article number28
JournalACM Transactions on Computer-Human Interaction
Issue number4
Publication statusPublished - 2012 Dec


  • Fitts
  • Gain
  • Interaction techniques
  • Large displays
  • Pointing
  • Welford

ASJC Scopus subject areas

  • Human-Computer Interaction


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