MAD saccade: Statistically robust saccade threshold estimation via the median absolute deviation

Benjamin Voloh, Marcus R. Watson, Seth König, Thilo Womelsdorf

Research output: Contribution to journalArticlepeer-review

Abstract

Saccade detection is a critical step in the analysis of gaze data. A common method for saccade detection is to use a simple threshold for velocity or acceleration values, which can be estimated from the data using the mean and standard deviation. However, this method has the downside of being influenced by the very signal it is trying to detect, the outlying velocities or accelerations that occur during saccades. We propose instead to use the median absolute deviation (MAD), a robust estimator of dispersion that is not influenced by outliers. We modify an algorithm proposed by Nystrom and colleagues, and quantify saccade detection performance in both simulated and human data. Our modified algorithm shows a significant and marked improvement in saccade detection-showing both more true positives and less false negatives-especially under higher noise levels. We conclude that robust estimators can be widely adopted in other common, automatic gaze classification algorithms due to their ease of implementation.

Original languageEnglish (US)
Article number3
JournalJournal of Eye Movement Research
Volume12
Issue number8
DOIs
StatePublished - 2019
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by a grant from the Canadian Institute of Health Research CIHR Grant MOP_102482

Keywords

  • Eye tracking
  • Head-free viewing
  • MAD
  • Median absolute deviation
  • Saccades

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