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ABSTRACT
This paper investigates the eye movement sequences of users visiting web pages repeatedly. We are interested in potential habituation due to repeated exposure. The scanpath theory posits that every person learns an idiosyncratic gaze sequence on first exposure to a stimulus and re-applies it on subsequent exposures. Josephson and Holmes (2002) tested the applicability of this hypothesis to web page revisitation but results were inconclusive. With a recurrent temporal pattern detection technique, we examine additional aspects and expose scanpaths. Results do not suggest direct applicability of the scanpath theory. While repetitive scan patterns occurred and were individually distinctive, their occurrence was variable, there were often several different patterns per person, and patterns were not primarily formed on the first exposure. However, extensive patterning occurred for some participants yet not for others which deserves further study into its determinants.

Germany 2010 HCI Usability Tobii eye tracking 1750 websites sequence repeat revisit scanpath pattern

in list: HCI & Usability

ABSTRACT
The scanpath comparison framework based on string editing is revisited. The previous method of clustering based on k-means "preevaluation" is replaced by the mean shift algorithm followed by elliptical modeling via Principal Components Analysis. Ellipse intersection determines cluster overlap, with fast nearest-neighbor search provided by the kd-tree. Subsequent construction of Y - matrices and parsing diagrams is fully automated, obviating prior interactive steps. Empirical validation is performed via analysis of eye movements collected during a variant of the Trail Making Test, where participants were asked to visually connect alphanumeric targets (letters and numbers). The observed repetitive position similarity index matches previously published results, providing ongoing support for the scanpath theory (at least in this situation). Task dependence of eye movements may be indicated by the global position index, which differs considerably from past results based on free viewing.

USA 2010 Tobii eye tracking 1750 scanpath comparison framework

in list: Eye Tracking Technology

ABSTRACT
Eye tracking specialists often need to understand and represent aggregate scanning strategies, but methods to identify similar scanpaths and aggregate multiple scanpaths have been elusive. A new method is proposed here to identify scanning strategies by aggregating groups of matching scanpaths automatically. A dataset of scanpaths is first converted to sequences of viewed area names, which are then represented in a dotplot. Matching sequences in the dotplot are found with linear regressions, and then used to cluster the scanpaths hierarchically. Aggregate scanning strategies are generated for each cluster and presented in an interactive dendrogram. While the clustering and aggregation method works in a bottom-up fashion, based on pair-wise matches, a top-down extension is also described, in which a scanning strategy is first input by cursor gesture, then matched against the dataset. The ability to discover both bottom-up and top-down strategy matches provides a powerful tool for scanpath analysis, and for understanding group scanning strategies.

USA 2010 Tobii eye tracking T60 Studio scanpath scanning pattern aggregation evaluation

in list: Eye Tracking Technology

Abstract
Visual scanning strategies have been often related to mental workload. In this study it has been investigated the relation between fixations distribution and workload on the basis of the consideration that low workload may be associated with regular patterns, indicating a regular check of the interface layout. According to this hypothesis, statistical indices providing information about the dispersion of point patterns should indicate differential patterns in the case of low and high workload. Participants were engaged in a simple visuo-motor task: the PC-based game known as "Asteroids". The game was modified to suit the experimental purposes. Participants were engaged in two experimental conditions: they were either requested to fire the randomly moving asteroids, or to avoid collision with the asteroids without shooting them. These conditions generated different amount of mental workload since collision avoidance was perceived as harder than shooting. The number of asteroids on screen was kept constant along blocks. Eye movements were recorded during the sessions and were analyzed using spatial statistics algorithms. Preliminary results showed sensitivity of spatial dispersion indices to variations in mental workload and their potential utility as triggers for adaptive automation.

HCI game scanpath visual Scanning spatial dispersion indices mental workload adaptive automation eye tracking Italy 2006 X50 Tobii

in list: Linguistics , HCI & Usability

Abstract
We investigated the influence of experimentally guided saccades and fixations on fMRI activation in brain regions specialized for face and object processing. Subjects viewed a static image of a face while a small fixation cross made a discrete jump within the image every 500 ms. Subjects were required to make a saccade and fixate the cross at its new location. Each run consisted of alternating blocks in which the subject was guided to make a series of saccades and fixations that constituted either a Typical or an Atypical face scanpath. Typical scanpaths were defined as a scanpath in which the fixation cross landed on the eyes or the mouth in 90% of all trials. Atypical scanpaths were defined as scanpaths in which the fixation cross landed on the eyes or mouth on 12% of all trials. The average saccade length was identical in both typical and atypical blocks, and both were preceded by a baseline block where the fixation cross made much smaller jumps in the middle of the screen. Within the functionally predefined face area of the ventral occipitotemporal cortex (VOTC), typical scanpaths evoked significantly more activity when compared to atypical scanpaths. A voxel-based analysis revealed a similar pattern in clusters of voxels located within VOTC, frontal eye fields, superior colliculi, intraparietal sulcus, and inferior frontal gyrus. These results demonstrate that fMRI activation is highly sensitive to the pattern of eye movements employed during face processing, and thus illustrates the potential confounding influence of uncontrolled eye movements for neuroimaging studies of face and object perception in normal and clinical populations.

fMRI face perception fusiform gyrus Controlled scanpath variation eye tracking USA 2007 Tobii 1750

in list: Cognitive & Behavioural Psychology

Abstract
To evaluate differences across viewers' visual attentional patterns, scanpath comparison has recently gained popularity in eye tracking studies, supplementing traditional objective (performance) and subjective measures (e.g., heat maps or [retrospective] talk-aloud). We introduce iComp, an open-source visualization tool that implements quantitative scanpath comparison in loci and sequence. iComp can be used to objectively compare the attentional qualities of synthetic images.

Tool Scanpath Visualization Comparison RTA compare attentional qualities images eye tracking USA 2006 Tobii 1750

in list: HCI & Usability