Characterizing user performance with assisted direct off-screen pointing

Barrett Ens, David Ahlström, Andy Cockburn, Pourang Irani

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

13 Citations (Scopus)

Abstract

The limited viewport size of mobile devices requires that users continuously acquire information that lies beyond the edge of the screen. Recent hardware solutions are capable of continually tracking a user's finger around the device. This has created new opportunities for interactive solutions, such as direct off-screen pointing: the ability to directly point at objects that are outside the viewport. We empirically characterize user performance with direct off-screen pointing when assisted by target cues. We predict time and accuracy outcomes for direct off-screen pointing with existing and derived models. We validate the models with good results (R2 ≥ 0.9) and reveal that direct off-screen pointing takes up to four times longer than pointing at visible targets, depending on the desired accuracy tradeoff. Pointing accuracy degrades logarithmically with target distance. We discuss design implications in the context of several real-world applications.

Original languageEnglish
Title of host publicationMobile HCI 2011 - 13th International Conference on Human-Computer Interaction with Mobile Devices and Services
Pages485-494
Number of pages10
DOIs
Publication statusPublished - 27 Oct 2011
Externally publishedYes
EventInternational Conference on Human-Computer Interaction with Mobile Devices and Services 2011 - Stockholm, Sweden
Duration: 30 Aug 20112 Sep 2011
Conference number: 13th

Conference

ConferenceInternational Conference on Human-Computer Interaction with Mobile Devices and Services 2011
Abbreviated titleMobileHCI 2011
CountrySweden
CityStockholm
Period30/08/112/09/11

Keywords

  • direct off-screen pointing
  • Fitts' law
  • off-screen target visualizations
  • performance models
  • steering law

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