Visual complexity in human-machine interaction = Visuelle Komplexität in der Mensch-Maschine Interaktion

Visuelle Komplexität wird oft als der Grad an Detail oder Verworrenheit in einem Bild definiert (Snodgrass & Vanderwart, 1980). Diese hat Einfluss auf viele Bereiche des menschlichen Lebens, darunter auch solche, die die Interaktion mit Technologie invol-vieren. So wurden Effekte visueller Komplexität etwa im Straßenverkehr (Edquist et al., 2012; Mace & Pollack, 1983) oder bei der Interaktion mit Software (Alemerien & Magel, 2014) oder Webseiten (Deng & Poole, 2010; Tuch et al., 2011) nachgewie-sen. Obwohl die Erforschung visueller Komplexität bereits bis auf die Gestaltpsycho-logen zurückgeht, welche etwa mit dem Gestaltprinzip der Prägnanz die Bedeutung von Simplizität und Komplexität im Wahrnehmungsprozess verankerten (Koffka, 1935; Wertheimer, 1923), sind weder die Einflussfaktoren visueller Komplexität, noch die Zusammenhänge mit Blickbewegungen oder mentaler Beanspruchung bisher ab-schließend erforscht. Diese Punkte adressiert die vorliegende Arbeit mithilfe von vier empirischen Forschungsarbeiten. In Studie 1 wird anhand der Komplexität von Videos in Leitwarten sowie der Effekte auf subjektive, physiologische und Leistungsparameter mentaler Beanspruchung die Bedeutung des Konstruktes im Bereich der Mensch-Maschine Interaktion untersucht. Studie 2 betrachtet die dimensionale Struktur und die Bedeutung verschiedener Ein-flussfaktoren visueller Komplexität genauer, wobei unterschiedliches Stimulusmaterial genutzt wird. In Studie 3 werden mithilfe eines experimentellen Ansatzes die Auswir-kungen von Einflussfaktoren visueller Komplexität auf subjektive Bewertungen sowie eine Auswahl okularer Parameter untersucht. Als Stimuli dienen dabei einfache, schwarz-weiße Formenmuster. Zudem werden verschiedene computationale und oku-lare Parameter genutzt, um anhand dieser Komplexitätsbewertungen vorherzusagen. Dieser Ansatz wird in Studie 4 auf Screenshots von Webseiten übertragen, um die Aussagekraft in einem anwendungsnahen Bereich zu untersuchen. Neben vorangegangenen Forschungsarbeiten legen insbesondere die gefundenen Zusammenhänge mit mentaler Beanspruchung nahe, dass visuelle Komplexität ein relevantes Konstrukt im Bereich der Mensch-Maschine Interaktion darstellt. Dabei haben insbesondere quantitative und strukturelle, aber potentiell auch weitere Aspekte Einfluss auf die Bewertung visueller Komplexität sowie auf das Blickverhalten der Be-trachter. Die gewonnenen Ergebnisse erlauben darüber hinaus Rückschlüsse auf die Zusammenhänge mit computationalen Maßen, welche in Kombination mit okularen Parametern gut für die Vorhersage von Komplexitätsbewertungen geeignet sind. Die Erkenntnisse aus den durchgeführten Studien werden im Kontext vorheriger For-schungsarbeiten diskutiert. Daraus wird ein integratives Forschungsmodell visueller Komplexität in der Mensch-Maschine-Interaktion abgeleitet

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Effects of online advertising on children's visual attention and task performance during free and goal-directed internet use : A media psychology approach to children's website interaction and advert distraction

This dissertation consists of four eye-tracking studies that investigate how salient online advertising and children's level of executive function contributes to their advert distraction. In Study 1, children aged 9 were instructed to surf freely on the internet while all advert material appearing on-screen was registered. The analyses examined how perceptual prominence in each online advert was related to children's visual attention. In Study 2, a mock-up advergame website was designed with controlled advert conditions, and children aged 9 and 12 were instructed to solve a number of in-game tasks. This study investigated the combined effects of perceptual prominence (e.g. abrupt onset) and content relevance (e.g. personalized content) on children's advert distraction. The results of the first two studies showed significant positive effects of advert saliency on children's visual attention. Due to the task-oriented research design used in the second study, it was possible to interpret these effects on visual attention in terms of advert distraction. Both studies showed that higher levels of inhibitory control in children significantly decreased the effects of advert saliency on visual attention and advert distraction.The following two studies, investigated how advert animation affected children's online reading comprehension and information search on commercial websites. In Study 3, children aged 9 were presented with factual texts that they were instructed to read in order to answer comprehension questions. Each text was presented on a web page which also featured static or animated online adverts. In Study 4, children aged 9 were instructed to solve two online task types featuring concurrent online advertising: reading and information search. The results of these studies showed that animated online advertising had significant negative effects on children's task performance. In the third study, it was found that animated adverts had a negative effect on children's reading comprehension, and that this negative effect was stronger among children with low levels of inhibitory control. The fourth study found that advert animation had a significant positive effect on children's cognitive load across task types. Taken together, this dissertation project has studied children's online advert distraction in a wide range of realistic internet usage situations

Hierarchical representations for spatio-temporal visual attention: modeling and understanding

Mención Internacional en el título de doctorDentro del marco de la Inteligencia Artificial, la Visión Artificial es una disciplina científica que tiene como objetivo simular automaticamente las funciones del sistema visual humano, tratando de resolver tareas como la localización y el reconocimiento de objetos, la detección de eventos o el seguimiento de objetos....Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Luis Salgado Álvarez de Sotomayor.- Secretario: Ascensión Gallardo Antolín.- Vocal: Jenny Benois Pinea

Novel perspectives and approaches to video summarization

The increasing volume of videos requires efficient and effective techniques to index and structure videos. Video summarization is such a technique that extracts the essential information from a video, so that tasks such as comprehension by users and video content analysis can be conducted more effectively and efficiently. The research presented in this thesis investigates three novel perspectives of the video summarization problem and provides approaches to such perspectives. Our first perspective is to employ local keypoint to perform keyframe selection. Two criteria, namely Coverage and Redundancy, are introduced to guide the keyframe selection process in order to identify those representing maximum video content and sharing minimum redundancy. To efficiently deal with long videos, a top-down strategy is proposed, which splits the summarization problem to two sub-problems: scene identification and scene summarization. Our second perspective is to formulate the task of video summarization to the problem of sparse dictionary reconstruction. Our method utilizes the true sparse constraint L0 norm, instead of the relaxed constraint L2,1 norm, such that keyframes are directly selected as a sparse dictionary that can reconstruct the video frames. In addition, a Percentage Of Reconstruction (POR) criterion is proposed to intuitively guide users in selecting an appropriate length of the summary. In addition, an L2,0 constrained sparse dictionary selection model is also proposed to further verify the effectiveness of sparse dictionary reconstruction for video summarization. Lastly, we further investigate the multi-modal perspective of multimedia content summarization and enrichment. There are abundant images and videos on the Web, so it is highly desirable to effectively organize such resources for textual content enrichment. With the support of web scale images, our proposed system, namely StoryImaging, is capable of enriching arbitrary textual stories with visual content