Enhancing KLM (Keystroke-Level Model) to fit touch screen mobile devices

Karim Mohsen Mahmoud El Batran, Mark Dunlop

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

21 Citations (Scopus)
896 Downloads (Pure)


This short paper introduces an enhancement to the Keystroke-Level Model (KLM) by extending it with three new operators to describe interactions on mobile touchscreen devices. Based on Fitts’s Law we modelled a performance measure estimate equation for each common touch screen interaction. Three prototypes were developed to serve as a test environment in which to validate Fitts’s equations and estimate the parameters for these interactions. A total of 3090 observations were made with a total of 51 users. While the studies confirmed each interaction fitted well to Fitts’s Law for most interactions, it was noticed that Fitts’s Law does not fit well for interactions with an Index of Difficulty exceeding 4 bits, highlighting a possible maximum comfortable stretch. Based on results, the following approximate movement times for KLM are suggested: 70ms for a short untargeted swipe, 200ms for a half-screen sized zoom, and 80ms for an icon pointing from a home position. These results could be used by developers of mobile phone and tablet applications to describe tasks as a sequence of the operators used and to predict user interaction times prior to creating prototypes.
Original languageEnglish
Title of host publicationProceedings of the 16th International Conference on Human-Computer Interaction with Mobile Devices and Services
Number of pages4
Publication statusPublished - Sep 2014
EventMobileHCI 2014 - Human-computer interaction with mobile devices & services - Toronto, Canada
Duration: 23 Sep 2014 → …


ConferenceMobileHCI 2014 - Human-computer interaction with mobile devices & services
Period23/09/14 → …


  • HCI
  • interaction modelling .
  • touch screen interaction
  • mobile devices


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