title: One algorithm to rule them all? An evaluation and discussion of ten eye movement event-detection algorithms.
abstract: Almost all eye-movement researchers use algorithms to parse raw data and detect distinct types of eye movement events, such as fixations, saccades, and pursuit, and then base their results on these. Surprisingly, these algorithms are rarely evaluated. We evaluated the classifications of ten eye-movement event detection algorithms, on data from an SMI HiSpeed 1250 system, and compared them to manual ratings of two human experts. The evaluation focused on fixations, saccades, and post-saccadic oscillations. The evaluation used both event duration parameters, and sample-by-sample comparisons to rank the algorithms. The resulting event durations varied substantially as a function of what algorithm was used. This evaluation differed from previous evaluations by considering a relatively large set of algorithms, multiple events, and data from both static and dynamic stimuli. The main conclusion is that current detectors of only fixations and saccades work reasonably well for static stimuli, but barely better than chance for dynamic stimuli. Differing results across evaluation methods make it difficult to select one winner for fixation detection. For saccade detection, however, the algorithm by Larsson, Nyström and Stridh (IEEE Transaction on Biomedical Engineering, 60(9):2484-2493,2013) outperforms all algorithms in data from both static and dynamic stimuli. The data also show how improperly selected algorithms applied to dynamic data misestimate fixation and saccade properties.
authors.affiliation: Eye Information Group, IT University of Copenhagen, Copenhagen, Denmark. Richard.Andersson@lucs.lu.se.|Department of Philosophy and Cognitive Science, Lund University, Box 192, 221 00, Lund, Sweden. Richard.Andersson@lucs.lu.se.
authors.forename: Richard
authors.initials: R
authors.lastname: Andersson
authors.affiliation: Department of Biomedical Engineering, Lund University, Lund, Sweden.
authors.forename: Linnea
authors.initials: L
authors.lastname: Larsson
authors.affiliation: Humanities Laboratory, Lund University, Lund, Sweden.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Holmqvist
authors.affiliation: Department of Biomedical Engineering, Lund University, Lund, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Stridh
authors.affiliation: Humanities Laboratory, Lund University, Lund, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Nyström
mesh_terms: D000465:Algorithms; D003625:Data Collection / Q000379:methods*; D005133:Eye Movements / Q000502:physiology*; D006801:Humans
keywords: Eye-tracking; Inter-rater reliability; Parsing