Impact Activation Improves Rapid Button Pressing

In Proceedings of the ACM Conference on Human Factors in Computing Systems, CHI 2018.
What is the right moment to activate a keystroke?
  • An impact point (when a key hits its bottom) produces the most salient tactile sensation.
  • Activating a key at its impact point is better aligned with users' intended timing.
  • The technique was 94% better than the regular activation method for a push- button (Cherry MX switch) and 37% for a touch button (capacitive touch sensor).

Impact Activation Concept

The activation point of a button is defined as the depth at which it invokes a make signal. Regular buttons are activated during the downward stroke, which occurs within the first 20 ms of a press. The remaining portion, which can be as long as 80 ms, has not been examined for button activation for reason of mechanical limitations. The paper presents a technique and empirical evidence for an activation technique called Impact Activation, where the button is activated at its maximal impact point. We argue that this technique is advantageous particularly in rapid, repetitive button pressing, which is common in gaming and music applications. We report on a study of rapid button pressing, wherein users’ timing accuracy improved significantly with use of Impact Activation. The technique can be implemented for modern push-buttons and capacitive sensors that generate a continuous signal.


All code and data are open for anyone to use.

  • Data
    • Experimental data reported in the paper
      In the excel document, 'participant' tap contains metatdata of participants, and 'TallTable' tap contains averaged success rate and asynchronies for each condition. Find descriptions at the right side of the table.
  • Data
Press Releases

PDF, 1.4 MB
Kim, S., Lee. B., & Oulasvirta, A. 2018. Impact Activation Improves Rapid Button Pressing In Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems (CHI ’18).

author = {Kim, Sunjun and Lee, Byungjoo and Oulasvirta, Antti},
booktitle = {Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems (CHI '18)},
title = {{Impact Activation Improves Rapid Button Pressing}},
year = {2018}
publisher = {ACM}
doi = {}
keywords = {impact activation, button design, activation point, temporal pointing, rapid tapping}

For questions and further information, please contact:

Sunjun Kim

Email: (at)

Acknowledgements: This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement 637991) and the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (NRF-2017R1C1B2002101). We also thank Jong-In Lee for help with the experiment and Jussi Jokinen for advice on statistical-test reporting.