Perceptual Manipulations for Hiding Image Transformations in Virtual Reality

Users of a virtual reality make frequent gaze shifts and head movements to explore their surrounding environment. Saccades are rapid, ballistic, conjugate eye movements that reposition our gaze, and in doing so create large-field motion on our retina. Due to the high speed motion on the retina during saccades, the brain suppresses the visual signals from the eye, a perceptual phenomenon known as the saccadic suppression. These moments of visual blindness can help hide the display graphical updates in a virtual reality. In this dissertation, I investigated how the visibility of various image transformations differed, during combinations of saccade and head rotation conditions. Additionally, I studied how hand and gaze interaction, affected image change discrimination in an inattentional blindness task. I conducted four psychophysical experiments in desktop or head-mounted VR. In the eye tracking studies, users viewed 3D scenes, and were triggered to make a vertical or horizontal saccade. During the saccade an instantaneous translation or rotation was applied to the virtual camera used to render the scene. Participants were required to indicate the direction of these transitions after each trial. The results showed that type and size of the image transformation affected change detectability. During horizontal or vertical saccades, rotations along the roll axis were the most detectable, while horizontal and vertical translations were least noticed. In a second similar study, I added a constant camera motion to simulate a head rotation, and in a third study, I compared active head rotation with a simulated rotation or a static head. I found less sensitivity to transsaccadic horizontal compared to vertical camera shifts during simulated or real head pan. Conversely, during simulated or real head tilt observers were less sensitive to transsaccadic vertical than horizontal camera shifts. In addition, in my multi-interactive inattentional blindness experiment, I compared sensitivity to sudden image transformations when a participant used their hand and gaze to move and watch an object, to when they only watched it move. The results confirmed that when involved in a primary task that requires focus and attention with two interaction modalities (gaze and hand), a visual stimuli can better be hidden than when only one sense (vision) is involved. Understanding the effect of continuous head movement and attention on the visibility of a sudden transsaccadic change can help optimize the visual performance of gaze-contingent displays and improve user experience. Perceptually suppressed rotations or translations can be used to introduce imperceptible changes in virtual camera pose in applications such as networked gaming, collaborative virtual reality and redirected walking. This dissertation suggests that such transformations can be more effective and more substantial during active or passive head motion. Moreover, inattentional blindness during an attention-demanding task provides additional opportunities for imperceptible updates to a visual display

Perceptual Manipulations for Hiding Image Transformations in Virtual Reality

Users of a virtual reality make frequent gaze shifts and head movements to explore their surrounding environment. Saccades are rapid, ballistic, conjugate eye movements that reposition our gaze, and in doing so create large-field motion on our retina. Due to the high speed motion on the retina during saccades, the brain suppresses the visual signals from the eye, a perceptual phenomenon known as the saccadic suppression. These moments of visual blindness can help hide the display graphical updates in a virtual reality. In this dissertation, I investigated how the visibility of various image transformations differed, during combinations of saccade and head rotation conditions. Additionally, I studied how hand and gaze interaction, affected image change discrimination in an inattentional blindness task. I conducted four psychophysical experiments in desktop or head-mounted VR. In the eye tracking studies, users viewed 3D scenes, and were triggered to make a vertical or horizontal saccade. During the saccade an instantaneous translation or rotation was applied to the virtual camera used to render the scene. Participants were required to indicate the direction of these transitions after each trial. The results showed that type and size of the image transformation affected change detectability. During horizontal or vertical saccades, rotations along the roll axis were the most detectable, while horizontal and vertical translations were least noticed. In a second similar study, I added a constant camera motion to simulate a head rotation, and in a third study, I compared active head rotation with a simulated rotation or a static head. I found less sensitivity to transsaccadic horizontal compared to vertical camera shifts during simulated or real head pan. Conversely, during simulated or real head tilt observers were less sensitive to transsaccadic vertical than horizontal camera shifts. In addition, in my multi-interactive inattentional blindness experiment, I compared sensitivity to sudden image transformations when a participant used their hand and gaze to move and watch an object, to when they only watched it move. The results confirmed that when involved in a primary task that requires focus and attention with two interaction modalities (gaze and hand), a visual stimuli can better be hidden than when only one sense (vision) is involved. Understanding the effect of continuous head movement and attention on the visibility of a sudden transsaccadic change can help optimize the visual performance of gaze-contingent displays and improve user experience. Perceptually suppressed rotations or translations can be used to introduce imperceptible changes in virtual camera pose in applications such as networked gaming, collaborative virtual reality and redirected walking. This dissertation suggests that such transformations can be more effective and more substantial during active or passive head motion. Moreover, inattentional blindness during an attention-demanding task provides additional opportunities for imperceptible updates to a visual display

The Relationship between Social Capital and Quality of Life among Patients Referring to Diabetes Centers in Isfahan, Iran

Background. Studies have shown that the relationship between social capital (SC) and quality of life (QOL) has an important role in care, prevention, and treatment of some patients. The present study was conducted with the aim to determine the relationship between social capital and QOL of patients with type 2 diabetes. Materials and Methods. This descriptive, correlational study was conducted on 215 individuals selected through quota sampling. To assess social capital, the Social Capital Questionnaire was used, and to evaluate the QOL of patients with type 2 diabetes, the Diabetes Quality of Life (DQOL) Brief Clinical Inventory was used. Data were analyzed using the Pearson correlation and regression analysis. Results. A significant relationship was observed between QOL and social capital in patients with diabetes. Moreover, social capital explained 14% of variance in QOL and with the addition of other accompanying diseases, this was increased to 19%. Conclusion. The results of this study can be useful for health care providers to improve the health of patients with diabetes. They also help patients to better manage and cope with their illness

Robust Real-Time Gradient-based Eye Detection and Tracking Using Transform Domain and PSO-Based Feature Selection

Despite numerous research on eye detection and tracking, this field of study remains challenging due to the individuality of eyes, occlusion, and variability in scale, location, and light conditions. This paper combines a techniques of feature extraction and a feature selection method to achieve a significant increase in eye recognition. Subspace methods may improve detection efficiency and accuracy of eye centers detection using dimensionality reduction. In this study, HoG descriptor is used to lay the ground for BPSO based feature selection. Histogram of Oriented Gradient (HoG) features are used for efficient extraction of pose, translation and illumination invariant features. HoG descriptors uses the fact that local object appearance and shape within an image can be described by the distribution of intensity gradients or edge directions. The method upholds invariance to geometric and photometric transformations. The performance of presented method is evaluated using several benchmark datasets, namely, BioID and RS-DMV. Experimental results obtained by applying the proposed algorithm on BioID dataset show that the proposed system outperforms other eye recognition systems. A significant increase in the recognition rate is achieved when using the combination of HoG descriptor, BPSO, and SVM for feature extraction, feature selection and training phase respectively. The Recognition rate for BioID dataset was 99.6% and the detection time was 15.24 msec for every single frame

Robust Real-Time Gradient-based Eye Detection and Tracking Using Transform Domain and PSO-Based Feature Selection

Despite numerous research on eye detection and tracking, this field of study remains challenging due to the individuality of eyes, occlusion, and variability in scale, location, and light conditions. This paper combines a techniques of feature extraction and a feature selection method to achieve a significant increase in eye recognition. Subspace methods may improve detection efficiency and accuracy of eye centers detection using dimensionality reduction. In this study, HoG descriptor is used to lay the ground for BPSO based feature selection. Histogram of Oriented Gradient (HoG) features are used for efficient extraction of pose, translation and illumination invariant features. HoG descriptors uses the fact that local object appearance and shape within an image can be described by the distribution of intensity gradients or edge directions. The method upholds invariance to geometric and photometric transformations. The performance of presented method is evaluated using several benchmark datasets, namely, BioID and RS-DMV. Experimental results obtained by applying the proposed algorithm on BioID dataset show that the proposed system outperforms other eye recognition systems. A significant increase in the recognition rate is achieved when using the combination of HoG descriptor, BPSO, and SVM for feature extraction, feature selection and training phase respectively. The Recognition rate for BioID dataset was 99.6% and the detection time was 15.24 msec for every single frame.Despite numerous research on eye detection and tracking, this field of study remains challenging due to the individuality of eyes, occlusion, and variability in scale, location, and light conditions. This paper combines a techniques of feature extraction and a feature selection method to achieve a significant increase in eye recognition. Subspace methods may improve detection efficiency and accuracy of eye centers detection using dimensionality reduction. In this study, HoG descriptor is used to lay the ground for BPSO based feature selection. Histogram of Oriented Gradient (HoG) features are used for efficient extraction of pose, translation and illumination invariant features. HoG descriptors uses the fact that local object appearance and shape within an image can be described by the distribution of intensity gradients or edge directions. The method upholds invariance to geometric and photometric transformations. The performance of presented method is evaluated using several benchmark datasets, namely, BioID and RS-DMV. Experimental results obtained by applying the proposed algorithm on BioID dataset show that the proposed system outperforms other eye recognition systems. A significant increase in the recognition rate is achieved when using the combination of HoG descriptor, BPSO, and SVM for feature extraction, feature selection and training phase respectively. The Recognition rate for BioID dataset was 99.6% and the detection time was 15.24 msec for every single frame.Despite numerous research on eye detection and tracking, this field of study remains challenging due to the individuality of eyes, occlusion, and variability in scale, location, and light conditions. This paper combines a techniques of feature extraction and a feature selection method to achieve a significant increase in eye recognition. Subspace methods may improve detection efficiency and accuracy of eye centers detection using dimensionality reduction. In this study, HoG descriptor is used to lay the ground for BPSO based feature selection. Histogram of Oriented Gradient (HoG) features are used for efficient extraction of pose, translation and illumination invariant features. HoG descriptors uses the fact that local object appearance and shape within an image can be described by the distribution of intensity gradients or edge directions. The method upholds invariance to geometric and photometric transformations. The performance of presented method is evaluated using several benchmark datasets, namely, BioID and RS-DMV. Experimental results obtained by applying the proposed algorithm on BioID dataset show that the proposed system outperforms other eye recognition systems. A significant increase in the recognition rate is achieved when using the combination of HoG descriptor, BPSO, and SVM for feature extraction, feature selection and training phase respectively. The Recognition rate for BioID dataset was 99.6% and the detection time was 15.24 msec for every single frame

The Relationship between Metacognitive Awareness of Reading Strategies and Students’ Academic Status in Isfahan University of Medical Sciences

Introduction: Learning and studying are considered among the most basic processes of every educational system. One of the most essential factor in determining learning behaviours, is metacognitive awareness and perception. This study was performed to determine the relationship between students’ metacognitive awareness of reading strategies and their academic status. Methods: In a descriptive correlational study, 191 students were selected through stratified random sampling out of total students of schools of Isfahan University of Medical Sciences in 2008-2009 academic years. Metacognitive Awareness of Reading Strategies Inventory (MARSI) was distributed among study sample. Academic status of students was defined based on their grand point average. Data was analyzed by SPSS version 10 software using Pearson correlation, independent t, and variance analysis tests. Results: The mean and standard deviation of metacognitive awareness score of students was 66.62 ± 14.8. The mean score of metacognitive awareness showed a significant correlation with students’ score of academic status meaning that students with average score higher that 17, had a significantly higher metacognitive awareness. Metacognitive awareness showed no significant relationship with variables of age, gender, and residence place. But, there was a significant relationship with academic level, so as MS students had higher metacognition score compared to that of PhD students. Conclusion: Metacognitive awareness and knowledge may lead to a more effective learning and studying in different courses. Considering the fact that metacognitive awareness and knowledge could be learnt both in family or educational settings in all levels of learners, it is recommended that educational and cultural institutions develop a comprehensive and detailed plan in this regard

Insurance companies’ point of view toward moral hazard incentives

Moral hazards are the result of an expansive range of factors mostly originating in the patients’ roles. The objective of the present study was to investigate patient incentives for moral hazards using the experiences of experts of basic Iranian insurance organizations. This was a qualitative research. Data were collected through semi-structured interviews. The study population included all experts of basic healthcare insurance agencies in the City of Isfahan, Iran, who were familiar with the topic of moral hazards. A total of 18 individuals were selected through purposive sampling and interviewed and some criteria such as data reliability and stability were considered. The anonymity of the interviewees was preserved. The data were transcribed, categorized, and then, analyzed through thematic analysis method. Through thematic analysis, 2 main themes and 11 subthemes were extracted. The main themes included economic causes and moral-cultural causes affecting the phenomenon of moral hazards resulted from patients’ roles. Each of these themes has some sub-themes. False expectations from insurance companies are rooted in the moral and cultural values of individuals. People with the insurance coverage make no sense if using another person insurance identification or requesting physicians for prescribing the medicines. These expectations will lead them to moral hazards. Individuals with any insurance coverage should consider the rights of insurance agencies as third party payers and supportive organizations which disburden them from economical loads in the time of sickness