CHAP: Open-source software for processing and analyzing pupillometry data

Ronen Hershman, Avishai Henik, Noga Cohen

Research output: Contribution to journalArticlepeer-review


Pupil dilation is an effective indicator of cognitive and affective processes. Although several eyetracker systems on the market can provide effective solutions for pupil dilation measurement, there is a lack of tools for processing and analyzing the data provided by these systems. For this reason, we developed CHAP: open-source software written in MATLAB. This software provides a user-friendly graphical user interface for processing and analyzing pupillometry data. Our software creates uniform conventions for the preprocessing and analysis of pupillometry data and provides a quick and easy-to-use tool for researchers interested in pupillometry. To download CHAP or join our mailing list, please visit CHAP’s website:

Original languageEnglish
Pages (from-to)1059-1074
Number of pages16
JournalBehavior Research Methods
Issue number3
StatePublished - 15 Jun 2019

Bibliographical note

Funding Information:
Author note This work was supported by funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC Grant Agreement no. 295644. We thank Desiree Meloul for helpful comments and useful input on this article. We also thank Yoav Kessler and Joseph Tzelgov for their advice regarding statistical analysis, and Stuart Steinhauer for his helpful input on pupil parameters. In addition, we thank Sam Hutton for his help with the adaptation of CHAP to EyeLink data, Reem Mulla for her help with the adaptation of CHAP to ASL data, Leah Fostick for her help with the adaptation of CHAP to Tobii data, and Nicole Amichetti for her help with the adaptation of CHAP for Mac users. Finally, we thank all present CHAP users for their helpful feedback and advice, especially Dina Devyatko and Dalit Milshtein, who also provided feedback on this article.

Publisher Copyright:
© 2019, The Psychonomic Society, Inc.


  • Bayesian analysis
  • GUI
  • Open-source code
  • Pupillometry

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Developmental and Educational Psychology
  • Arts and Humanities (miscellaneous)
  • Psychology (miscellaneous)
  • General Psychology


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