Research applying eye-tracking to usability testing is increasing in popularity. A great deal of data can be obtained with eye-tracking, but there is little guidance as to how eye-movement data can be used in software usability testing. In the current study, users’ eye-movements were recorded while they completed a series of tasks on one of three e-commerce websites specializing in educational toys. Four main research questions were addressed in this study: (1) Are eye-tracking measures correlated with the more traditional measures of website usability (e.g., success, time on task, number of pages visited); (2) Are eye-tracking measures sensitive to differences in task difficulty; (3) Are eye-tracking measures sensitive to differences in site usability; and (4) How does the design of a website drive user eye-movements? Traditional usability performance measures consisted of time on task, number of pages visited, and perceived task difficulty. Eye-tracking measures included the number of fixations, total dwell time, and average fixation duration. In general, all these measures were found to be highly correlated with one another, with the exception of average fixation duration. The two groups of measures generally agreed on differences in task difficulty; tasks showing high scores on one variable (e.g., time on task) showed high results on other measures (e.g., number of fixations). Similar agreement among measures was observed in comparisons of the sites on each task. The unique contributions of eye-tracking to usability testing were best realized in qualitative examinations of eye-tracking data in relation to specific areas of interest (AOIs) on site pages, which demonstrated this to be a useful tool in understanding how aspects of design may drive users’ visual exploration of a web page. / Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Psychology. / "May 2005."

A widely discussed philosophical puzzle in contemporary epistemology is the so-called sceptical paradox. Ascriber contextualism has taken centre stage as the anti-sceptical theory that purportedly offers the best solution to the sceptical paradox. Ascriber contextualists Stewart Cohen (1988, 1999) and Keith DeRose (1995) advertise their anti-sceptical theory as the one that exclusively explains and solves it. This is false advertising, however. My thesis, which has been greatly influenced by the critical work of Michael Williams (1991) and Duncan Pritchard (2005), is that the generation of the sceptical paradox depends on whether the epistemologist is an internalist or externalist about knowledge, and that the ascriber contextualist attempt to solve the sceptical paradox rests on a long history of mistakes concerning internalist assumptions made by externalists Fred Dretske (1970) and Robert Nozick (1981). By applying the semantic thesis of ascriber contextualism to epistemology, ascriber contextualists seek to emend the rejection of the closure principle made by these externalists. This rejection came from these externalists mistakenly making internalist assumptions when facing sceptical hypotheses. Unfortunately, ascriber contextualists leave much unfixed, and end up inheriting and suffering from the serious mistake about internalist assumptions that had plagued the epistemologies of these externalists and now infects the ascriber contextualist solution to the sceptical paradox. With the help of hindsight to examine this history and an appreciation of how the adoption of one of these respective views about knowledge makes all the difference for whether the sceptical paradox arises, we come to see that the contextualist solution to the sceptical paradox is unnecessary.

There is evidence to suggest that people from different cultures have different cognitive processing styles. For example, by measuring the eye movements of American and Chinese students when viewing pictures, Chua, Boland, and Nisbett (2005) found that American students fixated more on the focal object, whereas Chinese students fixated more on the background. In a subsequent object-recognition task, the Chinese students were less likely to correctly recognize old objects presented in new backgrounds than Americans did. This study used a similar scene-viewing task to investigate whether aging modulates these cultural differences in cognitive processing style. Like Chua et al., we found that young Chinese students spent longer fixating the background than did their Western counterparts. However, we failed to replicate the accompanying memory bias observed by Chua et al. Our strongest finding was that maintaining the original background facilitated memory for objects in young participants of both cultures but not for older participants. This result suggests that older adults had poorer memory for background details and/or had poorer integration of object and background.

Vehicle tracking in environments containing occlusion and clutter is an active research area. The problem of tracking vehicles through such environments presents a variety of challenges. These challenges include vehicle track initialization, tracking an unknown number of targets and the variations in real-world lighting, scene conditions and camera vantage. Scene clutter and target occlusion present additional challenges. A stochastic framework is proposed which allows for vehicles tracks to be identified from a sequence of images. The work focuses on the identification of vehicle tracks present in transportation scenes, namely, vehicle movements at intersections. The framework combines background subtraction and motion history based approaches to deal with the segmentation problem. The tracking problem is solved using a Monte Carlo Markov Chain Data Association (MCMCDA) method. The method includes a novel concept of including the notion of discrete, independent regions in the MCMC scoring function. Results are presented which show that the framework is capable of tracking vehicles in scenes containing multiple vehicles that occlude one another, and that are occluded by foreground scene objects.

Vehicle tracking in environments containing occlusion and clutter is an active research area. The problem of tracking vehicles through such environments presents a variety of challenges. These challenges include vehicle track initialization, tracking an unknown number of targets and the variations in real-world lighting, scene conditions and camera vantage. Scene clutter and target occlusion present additional challenges. A stochastic framework is proposed which allows for vehicles tracks to be identified from a sequence of images. The work focuses on the identification of vehicle tracks present in transportation scenes, namely, vehicle movements at intersections. The framework combines background subtraction and motion history based approaches to deal with the segmentation problem. The tracking problem is solved using a Monte Carlo Markov Chain Data Association (MCMCDA) method. The method includes a novel concept of including the notion of discrete, independent regions in the MCMC scoring function. Results are presented which show that the framework is capable of tracking vehicles in scenes containing multiple vehicles that occlude one another, and that are occluded by foreground scene objects.

Conical fluidized bed dryers are widely used in the pharmaceutical industry due to their high heat and mass transfer characteristics. Despite their widespread use, very little is known about the hydrodynamics of conical fluidized bed dryers. Wet pharmaceutical granule has high moisture content and wide particle size distribution (PSD), which can lead to poor mixing and non uniform drying. Uneven moisture content in the final product can adversely affect the quality and shelf life of these high value drugs. Previous studies on the conical fluidized bed dryers focused on the study of the gas phase, however motion of particulate phase has never been studied. Particle tracking is an important tool to study the motion of the particulate phase. Two particle tracking techniques were developed and used to study the motion of the particulate phase in a conical fluidized bed dryer. The first technique was radioactive particle tracking (RPT) which was developed at the University of Saskatchewan laboratory for a vessel having conical geometry. Experiments were conducted using dry pharmaceutical granule and during the actual drying of wet pharmaceutical granule. Two radioactive tracers of different sizes (1.6 to 2.6 mm) were tracked in each set of experiments to determine the effect of particle size on particle motion and particle mixing. Superficial gas velocities of 1, 1.5, 2 and 2.5m/s were used in dry bed studies to quantify the effect of superficial gas velocity. The second particle tracking technique was developed at the labs of Merck Frosst Canada Inc. Movies were captured using a high speed video camera coupled to a borescope and then analyzed off-line using image analysis software.Three powders having mean particle diameters of 774, 468 and 200 microns were used. Experiments were conducted at superficial gas velocities of 1.5, 2 and 3 m/s. <p>RPT revealed that there is a distinct circulation pattern of the particulate phase. Particles move upwards at high velocities near the centre of the bed and fall slowly near the walls. Furthermore, most of the gas flow is concentrated near the centre of the bed and the circulation pattern was observed at all the superficial gas velocities. Particle size of the tracer particle and PSD of the bed material had an appreciable impact on particle mixing with bigger particles exhibiting higher segregation tendencies than the smaller ones in the case of dry granule having a broad PSD. Particle segregation due to size difference was more pronounced at a superficial gas velocity of 1 m/s. However, segregation decreased with an increase in superficial gas velocity. During drying of wet granule, particle mixing and motion of the tracer particle was poor during the first 7 minutes of drying suggesting that most of the gas flow was concentrated near the centre of the bed. Particle mixing and average particle speeds increased considerably when the moisture content in the granule was less than 18 wt% suggesting a change in the hydrodynamics of the bed with the gas being more evenly distributed throughout the bed. Image analysis of high speed movies also suggested that a dilute region existed at the center of the bed. These observations were in agreement with the observations made by RPT.

A widely discussed philosophical puzzle in contemporary epistemology is the so-called sceptical paradox. Ascriber contextualism has taken centre stage as the anti-sceptical theory that purportedly offers the best solution to the sceptical paradox. Ascriber contextualists Stewart Cohen (1988, 1999) and Keith DeRose (1995) advertise their anti-sceptical theory as the one that exclusively explains and solves it. This is false advertising, however. My thesis, which has been greatly influenced by the critical work of Michael Williams (1991) and Duncan Pritchard (2005), is that the generation of the sceptical paradox depends on whether the epistemologist is an internalist or externalist about knowledge, and that the ascriber contextualist attempt to solve the sceptical paradox rests on a long history of mistakes concerning internalist assumptions made by externalists Fred Dretske (1970) and Robert Nozick (1981). By applying the semantic thesis of ascriber contextualism to epistemology, ascriber contextualists seek to emend the rejection of the closure principle made by these externalists. This rejection came from these externalists mistakenly making internalist assumptions when facing sceptical hypotheses. Unfortunately, ascriber contextualists leave much unfixed, and end up inheriting and suffering from the serious mistake about internalist assumptions that had plagued the epistemologies of these externalists and now infects the ascriber contextualist solution to the sceptical paradox. With the help of hindsight to examine this history and an appreciation of how the adoption of one of these respective views about knowledge makes all the difference for whether the sceptical paradox arises, we come to see that the contextualist solution to the sceptical paradox is unnecessary.

The main objective of this dissertation is to develop mean-squared error performance predictions for multiple target tracking. Envisioned as an approximate Cramer-Rao lower bound, these performance predictions allow a tracking system designer to quickly and efficiently predict the general performance trends of a tracking system. The symmetric measurement equation (SME) approach to multiple target tracking (MTT) lies at the heart of our method. The SME approach, developed by Kamen et al., offers a unique solution to the data association problem. Rather than deal directly with this problem, the SME approach transforms it into a nonlinear estimation problem. In this way, the SME approach sidesteps report-to-track associations. Developing performance predictions using the SME approach requires work in several areas: (1) extending SME tracking theory, (2) developing nonlinear filters for SME tracking, and (3) understanding techniques for computing Cramer-Rao error bounds in nonlinear filtering. First, on the SME front, we extend SME tracking theory by deriving a new set of SME equations for motion in two dimensions. We also develop the first realistic and efficient method for SME tracking in three dimensions. Second, we apply, for the first time, the unscented Kalman filter (UKF) and the particle filter to SME tracking. Using Taylor series analysis, we show how different SME implementations affect the performance of the EKF and UKF and show how Kalman filtering degrades for the SME approach as the number of targets rises. Third, we explore the Cramer-Rao lower bound (CRLB) and the posterior Cramer-Rao lower bound (PCRB) for computing MTT error predictions using the SME. We show how to compute performance predictions for multiple target tracking using the PCRB, as well as address confusion in the tracking community about the proper interpretation of the PCRB for tracking scenarios.

The time-course of the attentional bias to threat in women and men was examined in order to clarify the validity of the "vigilant-avoidant hypothesis" and extend findings with spider pictures (Rinck and Becker, 2006) to other ecologically valid stimuli. Two hundred thirty-one (104 men, 127 women) participants pre-selected for high and low trait anxiety completed a battery of mood measures and viewed a series of slides with competing angry versus friendly faces. For a subset of these participants (54 men, 50 women), fixations and gaze durations were recorded via an eye tracker. All participants completed a face recognition task and provided copy and live measures of digit ratio (2D:4D), a putative marker of prenatal androgen exposure. Consistent with results from Rinck and Becker (2006), it was predicted that highly anxious individuals would show a vigilant-avoidant pattern toward angry faces while lesser anxious individuals would attend equally to angry and friendly faces over time. In addition, it was hypothesized that the vigilant-avoidant pattern would be stronger in highly anxious women. For secondary hypotheses, it was expected that digit ratio would correlate positively with trait anxiety and that attentional patterns for threat would differ between those with low and high digit ratio. Results did not support a heightened threat bias in high anxious versus low anxious individuals. Both groups showed an early bias for the angry female face during the first 1500 ms of presentation and a general avoidance for the angry male face over the course of 60 s. Although no association was found between trait anxiety and digit ratio, there was a negative correlation between reports of obsessive-compulsive symptoms and live left hand digit ratio in men. Moreover, early attentional patterns for angry faces appeared to differ between women with low and high digit ratio, suggesting that prenatal androgen action may lead to cognitive biases associated with the development and maintenance of anxiety.

Optical flow indicates a computing method which utilizes the brightness variation of image motion in further image disposition, without the prior understanding of field, environment, or related object. It also reflects the image variation to compute the variation of optical flow field due to the motion of time and distance. The Essay content follows the optical flow as its basis theory consideration to find the direction of image motion. It utilizes the auto-focus principle to search the corrective focus basis, to proceed the identify analysis through the target object. To obtain the visual tracking result after the auto-focus of image definition, moving direction when achieve the target object. The application method is easily to determine the movement or stationary target in the certain field.