Abstract
Eye movement sequences—or scanpaths—vary
depending on the stimulus characteristics and the task
(Foulsham & Underwood Journal of Vision, 8(2), 6:1–17,
2008; Land, Mennie, & Rusted, Perception, 28, 1311–1328,
1999). Common methods for comparing scanpaths, however,
are limited in their ability to capture both the spatial and
temporal properties of which a scanpath consists. Here, we
validated a new method for scanpath comparison based on
geometric vectors, which compares scanpaths over multiple
dimensions while retaining positional and sequential information
(Jarodzka, Holmqvist, & Nyström, Symposium on
Eye-Tracking Research and Applications (pp. 211–218),
2010). “MultiMatch” was tested in two experiments and pitted
against ScanMatch (Cristino, Mathôt, Theeuwes, & Gilchrist,
Behavior Research Methods, 42, 692–700, 2010), the most
comprehensive adaptation of the popular Levenshtein method.
In Experiment 1, we used synthetic data, demonstrating the
greater sensitivity of MultiMatch to variations in spatial position.
In Experiment 2, real eye movement recordings were
taken from participants viewing sequences of dots, designed
to elicit scanpath pairs with commonalities known to be problematic
for algorithms (e.g., when one scanpath is shifted in
locus orwhen fixations fall on either side of anAOI boundary).
The results illustrate the advantages of a multidimensional
approach, revealing how two scanpaths differ. For instance, if
one scanpath is the reverse copy of another, the difference is in
the direction but not the positions of fixations; or if a scanpath
is scaled down, the difference is in the length of the saccadic
vectors but not in the overall shape. As well as having enormous
potential for any task in which consistency in eye movements
is important (e.g., learning), MultiMatch is particularly
relevant for “eye movements to nothing” in mental imagery
and embodiment-of-cognition research, where satisfactory
scanpath comparison algorithms are lacking.
Original language | English |
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Publication status | Published - May 2012 |
Event | Scandinavian Workshop on Applied Eye Tracking 2012 - Stockholm, Sweden Duration: 2 May 2012 → 5 May 2012 |
Workshop
Workshop | Scandinavian Workshop on Applied Eye Tracking 2012 |
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Abbreviated title | SWAET 2012 |
Country/Territory | Sweden |
City | Stockholm |
Period | 2/05/12 → 5/05/12 |
Keywords
- scanpaths
- eye tracking
- similarity