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In recent years, 3D graphics has become more available for web development with low-level access to graphics hardware and increased power of web browsers. With core browsing tasks for users being to quickly scan a website and find what they are looking for, can 3D graphics – or depth cues – be used to facilitate these tasks? Therefore, the main focus of this work was to examine user performance on websites in terms of visual attention. Previous research on the use of 3D graphics in web design and other graphical interfaces has yielded mixed results, but some suggest depth cues might be used to segment a visual scene and improve visual attention. In this work, the main question asked was:  How do depth cues affect visual search in a web-based environment? To examine the question, a user study was conducted where participants performed a visual search task on four different web-based prototypes with varying depth cues. The findings suggest depth cues might have a negative effect by increasing reaction time, but certain cues can improve task completion (hit rate) in text-rich web environments. It is further elaborated that it might be useful to look at the problem from a more holistic perspective, also emphasizing other factors such as visual complexity and prototypicality of websites.

This report is an evaluation of if it is good or bad to use a metaphor in order to display the results of an academic search engine in a web interface. In order to evaluate this we are describing our work with developing two different web interfaces for an academic search engine by the name Silverfish. This project has been a co-operation between Indian Institute of Information Technol- ogy in Bangalore, India and Malmˆ University K3, Sweden. To start our report we describe how we see our context we are to work within. We define our stakeholders as being academics worldwide and also define that we are working within a web 2.0 context. To strengthen our choices regarding the design process of the two different interfaces as well as in order to give more validity to our discussion surrounding metaphors we continue with presenting different studies and facts that give more weight to the above mentioned parts. To make it possible to create the interfaces we have made use of several methods. We give a short definition of how these methods are to be used and later describe in the design process how we have made use of them. To describe how we have made use of the methods as well as to describe how we have developed our prototypes we continue our report with describing the design process, regarding which deci- sions we have made and why we have made them. To summarize our report we come to a con- clusion regarding our thesis question; communicating related key phrases through web interface metaphors; good or bad? Regarding our question we have found that the orientational metaphor we are using does not work as it is supposed to. We believe that further studies are required in order to get a deeper un- derstanding of how the user understands the orientational metaphor we are using. This informa- tion could help us come to an understanding of how we could make better use of our orienta- tional metaphor, or help us find out of a metaphor that would be better to use than our orienta- tional metaphor.

When searching for an object, we store a mental representation of the target, which guides our search through the use of attention. The effectiveness of this search guidance varies depending on the task and the relationship between target and distractors. With a better understanding of how search guidance changes over time within a trial, we can better compare the differences between experimental conditions. Eye tracking data from a variety of search tasks were analyzed to determine how color guidance varied over the course of the trial. Color guidance for a given fixation was evaluated based on the distance in color space between the nearest object and the target color. These color differences were averaged over all of the trials and plotted based on when the fixation occurred in the trial. The results indicate that color guidance does not begin working at maximum effectiveness immediately. As the trial progresses, the average color difference decreases. After this initial decrease, if the target is not present, guidance becomes less selective and target dissimilar distractors are increasingly fixated. The color distance graphs were compared between experiments to reveal significant differences arising from the experimental conditions.

Many studies on feature-based search have found that color is preferentially used as a guiding feature. Most of these studies have utilized simple stimuli and the several studies that utilized real-world objects have been limited by the subjective color classification of objects. The current set of studies examined how search was guided by color and color proportions in real-world objects using color histograms to objectively classify color. To bridge the gap between simple stimuli and real-world objects, the first experiment examined how different color compositions in color conjunctions affected search. In the second experiment, real-world objects were objectively classified according to their primary color as determined by a color histogram, which was used to predict behavior. Finally, in the third experiment, real-world objects were classified by both their primary and secondary colors, which again, was used to predict behavior. Across three experiments the results demonstrated that search was guided by both colors of the target and there was more guidance to objects that matched the target's primary color than the target's secondary color. The results showed that theories derived from studying simple stimuli can be applied to more complex stimuli and tools developed in computer vision research can be used as an objective measure.

Military reconnaissance and surveillance (R&S) missions are a crucial ingredient in overall mission safety and success. Proper intelligence will provide the ability to counter and neutralize enemy positions and attacks. Accurate detection and identification of threatening targets is one the driving forces behind good R&S intelligence. Understanding this ability and how it is affected by possible field conditions (i.e., motion) was the primary focus of this study. Motion is defined in the current study as the perceived forward self-motion of unmanned ground vehicle (UGV) also called optical flow. For the purpose of this examination, both optical flow and the presence of a foil were manipulated. I examined how optical flow, perceived from an on-board frontal camera on a UGV, affected target detection and identification. The interaction of optical flow and foil distraction, as well as the level of influence each independently had on target detection and identification, were the principle examinations. The effects that were originally predicted for the influence of optical flow on the visual search and identification task were not supported. Across manipulations of optical flow (i.e., present, not present), detection and identification were not significantly different, suggesting that the interruption rates of optical flow were ineffective at 29 frames per second (fps). The most interesting finding in the data set was, in fact, related to the recognition measure. Participants were asked to classify the tank in which they had detected in the environment as either a target or non-target. When under conditions of non-optical flow, participants correctly rejected a foil tank as not being their target more often than they accepted the target as their actual target. These results, however, only appeared to have had an effect in the non-optical flow condition. Further research should be conducted to properly evaluate the effects of varying frame rate interruption on the perception of optical flow. This will subsequently lead to an understanding of the phenomenon that is optical flow, and how it ultimately affects detection and identification tasks.

Posttraumatic Stress Disorder (PTSD) is marked by avoidance, arousal, re-experiencing, and negative mood and cognition. To date, these symptoms are assessed using self-report measures (e.g., the PCL-5) and clinician administered assessments (e.g., the CAPS-5). While these are the present gold-standard assessments for PTSD, they still are prone to bias on behalf of both the administrator and the patient. Presently, there is evidence that individuals with PTSD perform differently than individuals without PTSD on certain cognitive tasks that measure attention bias and avoidance behaviors. As such, creating a battery of these tasks may be a viable route for objectively measuring PTSD. In an effort to provide preliminary evidence for such a battery, we used three cognitive assessments [the Emotional Stroop Task (EST), the Visual Search Task (VST), and the Approach Avoidance Task (AAT)] to assess cognitive performance in veterans with PTSD, and veterans and civilians without PTSD. We hypothesized that veterans with PTSD would perform worse than the other groups (as measured by reaction times and accuracy scores) following the presentation of combat-related stimuli compared to negative and positive stimuli. The results indicated that veterans with PTSD were generally slower across all conditions in the EST, had lower accuracy scores on the VST, and were slower in the combat condition compared to the other control groups in the AAT. This study provides preliminary support for the hypothesis that a battery of cognitive tasks may be an effective tool for objectively identifying PTSD. Furthermore, we discuss important methodological ways in which future studies could improve the sensitivity of these tasks.

The amount and variety of visual information presented on electronic displays is ever-increasing. Finding and acquiring relevant information in the most effective manner possible is of course desirable. While there are advantages to presenting a large number of information objects on a screen at the same time, it can also hinder fast detection of objects of interest. One way of addressing that problem is Voice Assisted Visual Search (VAVS). A user supported by VAVS calls out an object of interest and is immediately guided to the object by a highlighting cue. This thesis is an initial study of the VAVS user interface technique. The findings suggest that VAVS is a promising approach, supported by theory and practice. A working prototype shows that locating objects of interest can be sped up significantly, requiring only half the amount of time taken without the use of VAVS, on average. / Voice-Assisted Visual Search

Early breast cancer in women is best identified through high quality mammographic screening. This is achieved by well trained health professionals and appropriate imaging. Traditionally this has used X-ray film but is rapidly changing to utilise digital imaging with the resultant mammograms visually examined on high resolution clinical workstations. These digital images can also be viewed on a range of display devices, such as standard computer monitors or PDAs. In this thesis the potential of using such non-clinical workstation display devices for training purposes in breast screening has been investigated. The research introduces and reviews breast screening both in the UK and internationally where it concentrates upon China which is beginning screening. Various imaging technologies used to examine the breast are described, concentrating upon the move from using X-ray film to digital mammograms. Training in screening in the UK is detailed and it is argued that there is a need to extend this. Initially, a national survey of all UK mammography screeners within the National Health Breast Screening Programme (NHSBSP) was undertaken. This highlighted the current main difficulties of mammographic (film) interpretation training being tied to the device for inspecting these images. The screeners perceived the need for future digital imaging training that could be outside the breast screening centre; namely 3W training (Whatever training required, Whenever and Wherever). This is largely because the clinical workstations would logistically not be available for training purposes due to the daily screening demand. Whilst these workstations must be used for screening and diagnostic purposes to allow visualisation of very small detail in the images, it is argued here that training to identify such features can be undertaken on other devices where there is not the time constraints that exist during breast screening. A series of small pilot studies were then undertaken, trialling experienced radiologists with potential displays (PDAs and laptops) for mammographic image examination. These studies demonstrated that even on a PDA small mammographic features could be identified, albeit with difficulty, even with a very limited HCI manipulation tool. For training purposes the laptop, studied here with no HCI tool, was supported. Such promising results of display acceptability led to an investigation of mammographic inspection on displays of various sizes and resolutions. This study employed radiography students, potentially eventual screeners, who were eye tracked as they examined images on various sized displays. This showed that it could be possible to use a small PDA to deliver training. A detailed study then investigated whether aspects of an expert radiologist s visual inspection behaviour could be used to develop various training approaches. Four approaches were developed and examined using naïve observers who were eye tracked as they were trained and tested. The approaches were found to be all feasible to implement but of variable usefulness for delivering mammographic interpretation training; this was confirmed by opinions from a focus group of screeners. On the basis of the previous studies, over a period of eight months, a large scale study involving 15 film readers from major breast screening centres was conducted where they examined series of digital mammograms on a clinical workstation, monitor and an iPhone. Overall results on individuals performance, image manipulation behaviour and visual search data indicated that a standard monitor could be employed successfully as an alternative for the digital workstation to deliver on-demand mammographic interpretation training using the full mammographic case images. The small iPhone, elicited poor performance, and was therefore judged not suitable for delivering training with the software employed here. However, future software developments may well overcome its shortcomings. The potential to implement training in China was examined by studying the current skill level of some practicing radiologists and an examination of how they responded to the developed training approaches. Results suggest that such an approach would be also applicable in other countries with different levels of screening skills. On-going further work is also discussed: the improvement of performance evaluation in mammography; new visual research on other breast imaging modalities and using visual search with computer aided detection to assist mammographic interpretation training.