The pupil-size artefact (PSA) across time, viewing direction, and different eye trackers

Ignace T.C. Hooge; Diederick C. Niehorster; Roy S. Hessels; Dixon Cleveland; Marcus Nyström

doi:10.3758/s13428-020-01512-2

The pupil-size artefact (PSA) across time, viewing direction, and different eye trackers

Ignace T.C. Hooge^*, Diederick C. Niehorster, Roy S. Hessels, Dixon Cleveland, Marcus Nyström

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

The pupil size artefact (PSA) is the gaze deviation reported by an eye tracker during pupil size changes if the eye does not rotate. In the present study, we ask three questions: 1) how stable is the PSA over time, 2) does the PSA depend on properties of the eye tracker set up, and 3) does the PSA depend on the participants’ viewing direction? We found that the PSA is very stable over time for periods as long as 1 year, but may differ between participants. When comparing the magnitude of the PSA between eye trackers, we found the magnitude of the obtained PSA to be related to the direction of the eye-tracker-camera axis, suggesting that the angle between the participants’ viewing direction and the camera axis affects the PSA. We then investigated the PSA as a function of the participants’ viewing direction. The PSA was non-zero for viewing direction 0^∘ and depended on the viewing direction. These findings corroborate the suggestion by Choe et al. (Vision Research 118(6755):48–59, 2016), that the PSA can be described by an idiosyncratic and a viewing direction-dependent component. Based on a simulation, we cannot claim that the viewing direction-dependent component of the PSA is caused by the optics of the cornea.

Original language	English
Pages (from-to)	1986-2006
Number of pages	21
Journal	Behavior Research Methods
Volume	53
Issue number	5
DOIs	https://doi.org/10.3758/s13428-020-01512-2
Publication status	Published - Oct 2021

Keywords

Accuracy
Eye tracking
Gaze estimation
Monocular
Pupil-size artefact

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title = "The pupil-size artefact (PSA) across time, viewing direction, and different eye trackers",

abstract = "The pupil size artefact (PSA) is the gaze deviation reported by an eye tracker during pupil size changes if the eye does not rotate. In the present study, we ask three questions: 1) how stable is the PSA over time, 2) does the PSA depend on properties of the eye tracker set up, and 3) does the PSA depend on the participants{\textquoteright} viewing direction? We found that the PSA is very stable over time for periods as long as 1 year, but may differ between participants. When comparing the magnitude of the PSA between eye trackers, we found the magnitude of the obtained PSA to be related to the direction of the eye-tracker-camera axis, suggesting that the angle between the participants{\textquoteright} viewing direction and the camera axis affects the PSA. We then investigated the PSA as a function of the participants{\textquoteright} viewing direction. The PSA was non-zero for viewing direction 0∘ and depended on the viewing direction. These findings corroborate the suggestion by Choe et al. (Vision Research 118(6755):48–59, 2016), that the PSA can be described by an idiosyncratic and a viewing direction-dependent component. Based on a simulation, we cannot claim that the viewing direction-dependent component of the PSA is caused by the optics of the cornea.",

keywords = "Accuracy, Eye tracking, Gaze estimation, Monocular, Pupil-size artefact",

author = "Hooge, {Ignace T.C.} and Niehorster, {Diederick C.} and Hessels, {Roy S.} and Dixon Cleveland and Marcus Nystr{\"o}m",

note = "Funding Information: The authors thank Lund University Humanities Lab for the use of the laboratory, the EL1000p and the Spectrum. IH is also grateful to the Lund University Humanities Lab for their hospitality during a very pleasant stay in Lund. Author RH was supported by the Consortium on Individual Development (CID). CID is funded through the Gravitation program of the Dutch Ministry of Education, Culture, and Science and the NWO (Grant No. 024.001.003). The authors thank Annemiek Barsingerhorn (Barsingerhorn et al., 2018 ) for the inspiration to start DIY eye tracking, the software and the hardware advice. The eye tracking data and the Matlab implementation of eye model are available here: ?https://doi.org/10.5281/zenodo.4399125 ?. None of the experiments was preregistered. Publisher Copyright: {\textcopyright} 2021, The Author(s).",

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doi = "10.3758/s13428-020-01512-2",

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AU - Cleveland, Dixon

AU - Nyström, Marcus

N1 - Funding Information: The authors thank Lund University Humanities Lab for the use of the laboratory, the EL1000p and the Spectrum. IH is also grateful to the Lund University Humanities Lab for their hospitality during a very pleasant stay in Lund. Author RH was supported by the Consortium on Individual Development (CID). CID is funded through the Gravitation program of the Dutch Ministry of Education, Culture, and Science and the NWO (Grant No. 024.001.003). The authors thank Annemiek Barsingerhorn (Barsingerhorn et al., 2018 ) for the inspiration to start DIY eye tracking, the software and the hardware advice. The eye tracking data and the Matlab implementation of eye model are available here: ?https://doi.org/10.5281/zenodo.4399125 ?. None of the experiments was preregistered. Publisher Copyright: © 2021, The Author(s).

PY - 2021/10

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N2 - The pupil size artefact (PSA) is the gaze deviation reported by an eye tracker during pupil size changes if the eye does not rotate. In the present study, we ask three questions: 1) how stable is the PSA over time, 2) does the PSA depend on properties of the eye tracker set up, and 3) does the PSA depend on the participants’ viewing direction? We found that the PSA is very stable over time for periods as long as 1 year, but may differ between participants. When comparing the magnitude of the PSA between eye trackers, we found the magnitude of the obtained PSA to be related to the direction of the eye-tracker-camera axis, suggesting that the angle between the participants’ viewing direction and the camera axis affects the PSA. We then investigated the PSA as a function of the participants’ viewing direction. The PSA was non-zero for viewing direction 0∘ and depended on the viewing direction. These findings corroborate the suggestion by Choe et al. (Vision Research 118(6755):48–59, 2016), that the PSA can be described by an idiosyncratic and a viewing direction-dependent component. Based on a simulation, we cannot claim that the viewing direction-dependent component of the PSA is caused by the optics of the cornea.

AB - The pupil size artefact (PSA) is the gaze deviation reported by an eye tracker during pupil size changes if the eye does not rotate. In the present study, we ask three questions: 1) how stable is the PSA over time, 2) does the PSA depend on properties of the eye tracker set up, and 3) does the PSA depend on the participants’ viewing direction? We found that the PSA is very stable over time for periods as long as 1 year, but may differ between participants. When comparing the magnitude of the PSA between eye trackers, we found the magnitude of the obtained PSA to be related to the direction of the eye-tracker-camera axis, suggesting that the angle between the participants’ viewing direction and the camera axis affects the PSA. We then investigated the PSA as a function of the participants’ viewing direction. The PSA was non-zero for viewing direction 0∘ and depended on the viewing direction. These findings corroborate the suggestion by Choe et al. (Vision Research 118(6755):48–59, 2016), that the PSA can be described by an idiosyncratic and a viewing direction-dependent component. Based on a simulation, we cannot claim that the viewing direction-dependent component of the PSA is caused by the optics of the cornea.

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KW - Gaze estimation

KW - Monocular

KW - Pupil-size artefact

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SN - 1554-351X

VL - 53

SP - 1986

EP - 2006

JO - Behavior Research Methods

JF - Behavior Research Methods

IS - 5

ER -

The pupil-size artefact (PSA) across time, viewing direction, and different eye trackers

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Keywords

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