TY  - THES
A1  - Rothe, Colleen
T1  - Evaluation of Scanpath Comparison Metrics for Static and Dynamic Tasks
N2  - Purpose
Automated scanpath comparison metrics should deliver an objective method to
evaluate the similarity of scanpaths. The aim of this thesis is an evaluation of
seven existing scanpath comparison metrics in static and dynamic tasks in order
to provide a guidline that helps to decide which algorithm has to be chosen for a
special kind of task.
Methods
The applicability of the algorithms for a static, visual search task and a dynamic,
interactive video game task as well as their constraints and limitations were tested.
Therefore, binocular gaze data were recorded by using the eye tracking system The
Eye Tribe (The Eye Tribe ApS, Copenhagen/ Denmark). Objective task performance
measures from 21 subjects were used in order to create scanpath groupings
for which a relevant effect of dissimilarity was to be expected. Objective task performance
measures such as task performance time were statistically evaluated and
compared to the results gained by the comparison metrics.
Results
Four of the algorithms being used successfully identified differences for static and
dynamic tasks: MultiMatch, iComp, SubsMatch and the Hidden Markov Model.
ScanMatch was very sensitive for the static task but not applicable to the dynamic
task whereas FuncSim was suitable for dynamic but not for static tasks. Eyenalysis
failed to detect any effect.
Conclusion
The applicability of scanpath comparison metrics depends on the state of the task,
respectively on the kind of experimental set up. In future, the application area for
eye tracking will expand and an improvement of automated scanpath comparison
metrics is therefore required.
KW  - Eye tracking
KW  - Scanpath
KW  - Comparison metrics
KW  - Visual search
KW  - Fixation
KW  - Mustererkennung
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:944-opus4-1633
ER  - 
TY  - THES
A1  - Ungewiss, Judith
T1  - Parameters for Vigilance, Attention and Cognitive Workload within Eye Tracking Recordings
N2  - Purpose: Usually, a theory of attention upon gazed-at locations is applied. More parameters than gaze location can be derived to improve the theory of attention allocation. The aim of this study was to identify parameters related to eye tracking, that are suitable indicators of attention.
Methods: Binocular eye tracking data was collected with the Eye Tribe tracking system (The Eye Tribe Aps, Copenhagen, Denmark) for the task of visual exploration of the painting “Unexpected Visitors” by Ilya Repin. 20 subjects (valid data: 19/20) had to look at this painting for about two and a half minutes in order to generate fatigue and inattention. In a second step, suitable parameters of attention were transferred to a data set (8 subjects, valid data: 6/8) on a perimetric task executed with the OCTOPUS 900 perimeter (Haag-Streit, Köniz, Switzerland). Monocular parameters could be applied on the perimetric task, the error rate (false positive and false negative catch trials, 5 % each) were taken as additional parameter.
Results: For the image viewing task, the only parameter showing significance was the average level (a10) of fatigue waves (p = 0.00024, ANOVA, ∆ = -0.8316 px). Blink duration (∆ =-270.4 ms), pupil variability (∆ = -0.17868), saccade length (∆ =-0.3135 px) and fixation duration (∆ = 186.5 ms) did not change significantly, but showed relevant trends by differences ∆ of their median between the first and last tenth of the recording time. Blink rate and the Index of Cognitive Activity (ICA) did neither show significant changes nor relevant trends. Vergence accuracy failed to indicate fatigue due to variability between subjects and comparatively small effect size. For the perimetric data, in 3 of 6 subjects fatigue waves over a limited time window could be observed. Only for one subject, a relevant increase in false negative responses to catch trials (50 percentage points) could be observed.
Conclusion: Pupil diameter variability, saccade length, fixation duration and fatigue waves were the parameters indicating fatigue. Only the latter parameter has the potential to be applied to perimetric data.
N2  - Ziel: Aufmerksamkeit lässt sich nicht nur anhand von Blickzuwendungen beschreiben. Deutlich mehr Parameter können abgeleitet werden, um die Theorie der Aufmerksamkeitszuwendung zu verbessern. Diese Masterarbeit zielt auf die Identifikation von Parametern, die bei Eye Tracking Experimenten aufgezeichnet, aber teils nur selten ausgewertet werden, ab.
Methode: Bildbetrachtungsdaten für das Gemälde „Unexpected Visitors“ von Ilya Repin wurden mit einem binokularen Eye Tracker (The Eye Tribe Aps, Kopenhagen, Dänemark) bei 20 Probanden (gültige Daten: 19/20) für einen Zeitraum von zweieinhalb Minuten aufgenommen.
Geeignete Parameter wurden auf einen Datensatz zur Perimetrie (8 Probanden, gültige Daten: 6/8), aufgenommen mit einem OCTOPUS 900 Perimeter (Haag-Streit, Köniz, Schweiz), transferiert. Die Fehlerrate (falsch positive/falsch negative Fangfragen, je 5 %) wurde eruiert.
Ergebnisse: Aufmerksamkeits-Indikatoren zeigten signifikante Werte für Schläfrigkeitswellen (Average-Level 10, p = 0.00024, ANOVA, ∆ = -0.8316 px). Pupillenvariabilität (∆ = -0.17868), Saccadenlänge (∆ = -0.3135 px), Fixationsdauer (∆ = 186.5 ms) und Lidschlussdauer (∆ = -270.4 ms) zeigten keine signifikanten Änderungen, jedoch waren relevante Trends zu sehen, da die Mediane des jeweils ersten und letzten Zehntels der Aufnahmen sich um den Differenzbetrag ∆ unterschieden. Die Lidschlussfrequenz und der Index kognitiver Aktivität zeigten keine relevanten Trends. Die Vergenzgenauigkeit eignete sich aufgrund zu hoher Variabilität und zu geringer Effektgröße ebenfalls nicht als Indikator. Während der perimetrischen Untersuchung konnten nur bei 3 von 6 Probanden zeitlich begrenzte Schläfrigkeitswellen festgestellt werden. Nur ein Proband zeigte mit dem Einsetzen von Müdigkeit einen relevanten Anstieg falsch negativer Antworten auf Fangfragen (50 Prozentpunkte).
Fazit: Aufmerksamkeits-Indikatoren sind Pupillenvariabilität, Saccadenlänge, Fixationsdauer und Schläfrigkeitswellen. Lediglich der letztgenannte Parameter kann potenziell auf perimetrische Daten übertragen werden.
KW  - eye tracking, vigilance, attention, cognitive workload, visual exploration, perimetry
KW  - Eye Tracking, Vigilanz, Aufmerksamkeit, visuelle Exploration, Perimetrie
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:944-opus4-1396
ER  -