Identifying fixations and saccades in eye-tracking protocols

The process of fixation identification—separating and labeling fixations and saccades in eye-tracking protocols—is an essential part of eye-movement data analysis and can have a dramatic impact on higher-level analyses. However, algorithms for performing fixation identification are often described informally and rarely compared in a meaningful way. In this paper we propose a taxonomy of fixation identification algorithms that classifies algorithms in terms of how they utilize spatial and temporal information in eye-tracking protocols. Using this taxonomy, we describe five algorithms that are representative of different classes in the taxonomy and are based on commonly employed techniques. We then evaluate and compare these algorithms with respect to a number of qualitative characteristics. The results of these comparisons offer interesting implications for the use of the various algorithms in future work.

[1]  Rudy Den Buurman,et al.  Eye Movements and the Perceptual Span in Reading. , 1981 .

[2]  John R. Anderson,et al.  Integrating analogical mapping and general problem solving: the path-mapping theory , 2001, Cogn. Sci..

[3]  Joseph H. Goldberg,et al.  Eye-gaze-contingent control of the computer interface: Methodology and example for zoom detection , 1995 .

[4]  Tayyar Sen,et al.  The Effects of Task Variables and Prolonged Performance on Saccadic Eye Movement Parameters , 1984 .

[5]  Lawrence R. Rabiner,et al.  A tutorial on hidden Markov models and selected applications in speech recognition , 1989, Proc. IEEE.

[6]  P Suppes,et al.  Eye-movement models for arithmetic and reading performance. , 1990, Reviews of oculomotor research.

[7]  Albert F. Fuchs,et al.  THE SACCADIC SYSTEM , 1971 .

[8]  Casper J. Erkelens,et al.  The Initial Direction and Landing Position of Saccades , 1995 .

[9]  J. Stern.  Theoretical and applied aspects of eye movement research A. G. Gale and F. Johnson, (Elsevier Science Publishers B.V., Amsterdam, 1984) pp. xiii + 565, Dfl. 185 , 1985, Biological Psychology.

[10]  John R. Anderson,et al.  Mapping eye movements to cognitive processes , 1999 .

[11]  K. Rayner.  Eye Movements and Cognitive Processes in Reading, Visual Search, and Scene Perception , 1995 .

[12]  John R. Anderson,et al.  Tracing Eye Movement Protocols with Cognitive Process Models , 1998 .

[13]  H. Widdel.  Operational Problems in Analysing Eye Movements , 1984 .

[14]  David N. Lee,et al.  Where we look when we steer , 1994, Nature.

[15]  Francesco Maffioli,et al.  Algorithms for finding optimum trees: Description, use and evaluation , 1988 .

[16]  Robert W. Kentridge,et al.  Eye movement research : mechanisms, processes and applications , 1995 .

[17]  D. F. Fisher,et al.  Eye movements : cognition and visual perception , 1982 .

[18]  John A. Hartigan,et al.  Clustering Algorithms , 1975 .

[19]  L. Stark,et al.  Scanpaths in saccadic eye movements while viewing and recognizing patterns. , 1971, Vision research.

[20]  R. W. Ditchburn.  The function of small saccades , 1980, Vision Research.

[21]  Eileen Kowler.  Eye movements and their role in visual and cognitive processes. , 1990, Reviews of oculomotor research.