Master of Science / Psychological Sciences / Lester C. Loschky / A fundamental issue in visual attention is the relationship between the useful field of view (UFOV), the region of visual space where information is encoded within a single fixation, and eccentricity. A common assumption is that impairing attentional resources reduces the size of the UFOV (i.e. “tunnel vision”). However, most research has not accounted for eccentricity-dependent changes in spatial resolution, potentially conflating fixed visual properties with flexible changes in visual attention. Williams (1988; 1989) argued that foveal loads are necessary to reduce the size of the UFOV, producing "tunnel vision". Without a foveal load, it is argued that the attentional decrement is constant across the visual field (i.e. "general interference"). However, other research asserts that auditory working memory (WM) loads produce tunnel vision. To date, foveal versus auditory WM loads have not been compared to determine if they differentially change the size of the UFOV. In two experiments, we tested the effects of a foveal (rotated L vs. T discrimination) task, and an auditory WM (N-back) task on an extrafoveal (Gabor) discrimination task. Gabor patches were scaled for size and processing time to produce equal performance across the visual field under single task conditions, thus removing the confound of eccentricity-dependent differences in visual sensitivity. The results showed that while both foveal and auditory loads reduced Gabor orientation sensitivity, only the foveal load interacted with retinal eccentricity to produce tunnel vision, clearly demonstrating task-specific changes to the form of the UFOV. This has theoretical implications for understanding the UFOV.

Using eyes as an input modality for different control environments is a great area of interest for enhancing the bandwidth of human machine interaction and providing interaction functions when the use of hands is not possible. Interface design requirements in such implementations are quite different from conventional application areas. Both command-execution and feedback observation tasks may be performed by human eyes simultaneously. In order to control the motion of a mobile robot by operator gaze interaction, gaze contingent regions in the operator interface are used to execute robot movement commands, with different screen areas controlling specific directions. Dwell time is one of the most established techniques to perform an eye-click analogous to a mouse click. But repeated dwell time while switching between gaze-contingent regions and feedback-regions decreases the performance of the application. We have developed a dynamic gaze-contingent interface in which we merge gaze-contingent regions with feedback-regions dynamically. This technique has two advantages: Firstly it improves the overall performance of the system by eliminating repeated dwell time. Secondly it reduces fatigue of the operator by providing a bigger area to fixate in. The operator can monitor feedback with more ease while sending commands at the same time.

Interactive 3D computer graphics requires a lot of computational resources to render a high quality frame. Typically the process of rendering a frame assumes a naïve approach that the whole frame can be perceived by the user in uniform detail. This is often not true, within 2° horizontal eccentricity from point of gaze is where one can primarily perceive details. Adjusting the quality of a frame based on the visual acuity can increase rendering performance by a factor of five to six at the resolution 1920x1080 without sacrificing perceived quality (Guenter et al., 2012a). Doing so without the user being aware of the manipulation requires a highly sophisticated system with low system latency able to update the display fast enough. The current study aims to answer what system latency is required to support passive gaze-contingent techniques that requires close to real-time gaze data. A unique experiment design was developed exposing test subjects to different system latencies by varying eye-tracker and monitor frequency. The outcome from the current study with 20 participants indicates a configuration with the estimated worst case system latency of 60ms is capable of hiding manipulation for 55% of the participants. Lowering the worst case system latency to 42ms and 95% of the participants reported that they could not detect any change. The study concludes that the configuration with estimated worst case system latency of 42ms is able to support passive gaze-contingent techniques. / Interaktiv 3D datorgrafik kräver mycket dataresurser för att producera en högkvalitativ bildruta. Den typiska processen att producera en bildruta antar det naiva antagandet att hela bildrutan kan uppfattas av användaren i enhetlig detalj. Detta antagande är ofta inte sant. Mänskliga ögat kan uppfatta detaljer i 2° horisontell vinkel från blickfokus med minskande detaljrikedom i ökande vinkel. Att anpassa kvaliteten på en bildruta baserat på detta kan öka renderingsprestanda med en faktor 5-6 vid upplösningen 1920x1080, utan att minska på den subjektivt upplevda kvaliteten (Guenter et al., 2012a). Att kunna göra det utan att användaren är medveten om manipulation kräver ett mycket sofistikerat system med låg system latens för att uppdatera displayen tillräckligt snabbt. Denna studie syftar till att svara på vad för system latens som krävs för att stödja tekniker som kräver nära realtid blick uppgifter. Studien presenterar ett unikt experiment där testpersoner exponeras för olika system latenser genom att variera både skärm och ögonspårnings frekvenser. Resultatet från studien som baseras på 20 deltagare visar att en konfiguration med estimerad värsta fall system latens på 60ms kan dölja manipulation för 55% av deltagarna. Vid 42ms system latens i värsta fall uppgav 95% av deltagarna att de inte kunde upptäcka någon förändring. Studien drar slutsatsen att konfigurationen med beräknade värsta fall systemet latens på 42ms kan stödja passiva blickberoende tekniker. / <p>Mobile: 073-2420226 Email: robin@thunstroem.com</p>

Yes / Purpose: To demonstrate methods that enable visual field sensitivities to be compared with normative data without restriction to a fixed test pattern. Methods: Healthy participants (n = 60, age 19–50) undertook microperimetry (MAIA-2) using 237 spatially dense locations up to 13° eccentricity. Surfaces were fit to the mean, variance, and 5th percentile sensitivities. Goodness-of-fit was assessed by refitting the surfaces 1000 times to the dataset and comparing estimated and measured sensitivities at 50 randomly excluded locations. A leave-one-out method was used to compare individual data with the 5th percentile surface. We also considered cases with unknown fovea location by adding error sampled from the distribution of relative fovea–optic disc positions to the test locations and comparing shifted data to the fixed surface. Results: Root mean square (RMS) difference between estimated and measured sensitivities were less than 0.5 dB and less than 1.0 dB for the mean and 5th percentile surfaces, respectively. Root mean square differences were greater for the variance surface, median 1.4 dB, range 0.8 to 2.7 dB. Across all participants 3.9% (interquartile range, 1.8–8.9%) of sensitivities fell beneath the 5th percentile surface, close to the expected 5%. Positional error added to the test grid altered the number of locations falling beneath the 5th percentile surface by less than 1.3% in 95% of participants. Conclusions: Spatial interpolation of normative data enables comparison of sensitivity measurements from varied visual field locations. Conventional indices and probability maps familiar from standard automated perimetry can be produced. These methods may enhance the clinical use of microperimetry, especially in cases of nonfoveal fixation.

One way of increasing 3D rendering performance is the use of foveated rendering. In this thesis a novel foveated rendering technique called gaze contingent depth of field tessellation (GC DOF tessellation) is proposed. Tessellation is the process of subdividing geometry to increase detail. The technique works by applying tessellation to all objects within the focal plane, gradually decreasing tessellation levels as applied blur increases. As the user moves their gaze the focal plane shifts and objects go from blurry to sharp at the same time as the fidelity of the object increases. This can help hide the pops that occur as objects change shape. The technique was evaluated in a user study with 32 participants. For the evaluated scene the technique helped reduce the number of primitives rendered by around 70 % and frame time by around 9 % compared to using full adaptive tessellation. The user study showed that as the level of blur increased the detection rate for pops decreased, suggesting that the technique could be used to hide pops that occur due to tessellation. However, further research is needed to solidify these findings. / Ett sätt att öka renderingsprestanda i 3D applikationer är att använda foveated rendering. I denna uppsats presenteras en ny foveated rendering-teknik som kallas gaze contingent depth of field tessellering (GC DOF tessellering). Tessellering är när geometri delas i mindre delar för att öka detaljrikedom. Tekniken fungerar genom att applicera tessellering på alla objekt i fokalplanet och gradvis minska tesselleringsnivåer när oskärpan ökar. När användaren flyttar sin blick så flyttas fokalplanet och suddiga objekt blir skarpa samtidigt som detaljrikedomen i objektet ökar. Det kan hjälpa till att dölja de ’pops’ som uppstår när objekt ändrar form. Tekniken utvärderades i en användarstudie med 32 del- tagare. I den utvärderade scenen visade sig tekniken minska antalet renderade primitiver med ca 70 % och minska renderingstiden med ca 9 % jämfört med att använda full adaptiv tessellering. Användarstudien visade att när oskärpa ökade så minskade antalet som sa sig se ’pops’, vilket tyder på att tekniken kan användas för att dölja de ’pops’ som uppstår på grund av tessellering. Det behövs dock ytterligare forskning för att säkerställa dessa fynd.