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In everyday experience, visual motion is an extremely important source of information about the world. Motion cues are vital to our perception of where objects are and where they are moving. Biological motion cues give us the information from which to build the fine-grained, almost subconscious understanding of another's emotions and intentions that is so often necessary in social interactions.
Introduction Studies have shown considerable evidence of visual dysfunction in Autism Spectrum Disorders (ASD). Motion perception research in ASD reports a superior performance in processing motion information of fine details and neglects global information. However, there are many variabilities in these experimental results, particularly in adults with autism. Several theories have been put forward as the underlying cause(s) of motion deficits in autism. These include: enhanced local domain information processing at early visual area V1; abnormal processing at the higher visual cortical area MST including V5/MT; and/or abnormal functional and structural connectivity between and within cortical networks that are recruited during different motion processing tasks. In this study, we used multiple motion perception tasks in order to activate different visual neural networks that may contribute to perception of specific motion domains in order to understand visual perception abnormalities in autism. The specific aims of each experiment included in this thesis are as follow: - Chapter 3: To investigate the theory of enhanced local details and neglected global picture, using- for the first time- local/global motion coherence stimuli in autism. - Chapter 4: To investigate the neural response biased found in autism in response to radial optic flow. We used optic flow stimuli in self-heading direction discrimination tasks. - Chapter 5: To investigate whether speed parameter is normal in autism-based on the previous outcome- using drifting grating stimuli in a speed discrimination task. Participants and Methods This study recruited two groups of subjects -one with ASD (n = 14), and another with Typical Development (TD) (n= 14), age range (16- 40 years). - Chapter 3 : We used Random Dot Kinatogram (RDK) as global coherence stimuli and employed it in two tasks : (1) Coherent Motion (CM) task, where coherence levels were varied and the subjects had to detect the global direction of the coherent dots, (2) CM with Form From Motion (FfM) stimulus where the FfM consisted of one of four different shapes embedded in the global RDK task. - Chapter 4: We used RDK with optic flow stimuli, which investigated self-direction discrimination in two tasks: angle of eccentricity, and contrast sensitivity. In both tasks we randomized the dot density (15, 80 dots) and speed (4, 10 deg/sec) of the moving stimulus dots. - Chapter 5: We used a pair of drifting gratings with a spatial frequency 2 cycle/ degree, oriented vertically and drifting perpendicular to the direction of orientation, and varied the speed (2, 6 deg/ sec) and the stimuli presentation (250 - 500ms) Results - Chapter 3: Although adults with autism showed comparable performance in reporting global direction similar to the control group, their ability to process global properties, when FfM shape was embedded, declined ( Mean threshold ASD: MC= 13.58, CM-FfM= 30.65) In addition, ASD required more time to respond to global coherence even when their performance was comparable to that of the control group. - Chapter 4: No significant group differences were found for low dot density (15 dots), while high dot (80 dots) density showed low sensitivity to OF motion in the ASD group compared to the TD. Contrast sensitivity task, however, showed lower sensitivity in the ASD group for detecting OF motion when dot density was low (15 dots) and no differences at higher dot density (80 dots) was found. Both tasks showed no group differences in the dot speed changing and no significant differences in response time were observed. - Chapter 5: No group differences (p = 0.226) in sensitivity to speed-discrimination task were found between the ASD and control group in all parameters used in this experiment. The response times were also comparable between both groups (p = 0.855). Conclusions - Chapter 3: Motion perception in ASD found enhanced to local details particularly when motion stimuli involve both local/global information segregation at the same time. We suggest increased internal neural noise and worse external noise filtering as cause of poor global performance in this type of task. - Chapter 4: There were selective impairments in OF processing that may related to altered neural connectivity between the activated visual areas in ASD. Another suggestion might be related to long neural trajectory within higher visual areas, ex. MST. - Chapter 5: Normal motion processing may be found in ASD, however, it this might triggered by task complexity and the visual neural areas that are involved in processing motion information. The overall results suggest selective impairments in visual motion perception in ASD. These impairments would depend upon the task requirements and therefore on the activated visual networks that contribute to different aspects of motion information processing. The present studies provide novel findings in defining deficits in motion perception in autism, which thereby may contribute in understanding disturbed visual function in ASD.
Motion processing is an essential piece of the complex brain machinery that allows us to reconstruct the 3D layout of objects in the environment, to break camouflage, to perform scene segmentation, to estimate the ego movement, and to control our action. Although motion perception and its neural basis have been a topic of intensive research and modeling the last two decades, recent experimental evidences have stressed the dynamical aspects of motion integration and segmentation. This book presents the most recent approaches that have changed our view of biological motion processing. These new experimental evidences call for new models emphasizing the collective dynamics of large population of neurons rather than the properties of separate individual filters. Chapters will stress how the dynamics of motion processing can be used as a general approach to understand the brain dynamics itself.
The Cambridge Handbook of Applied Perception Research covers core areas of research in perception with an emphasis on its application to real-world environments. Topics include multisensory processing of information, time perception, sustained attention, and signal detection, as well as pedagogical issues surrounding the training of applied perception researchers. In addition to familiar topics, such as perceptual learning, the Handbook focuses on emerging areas of importance, such as human-robot coordination, haptic interfaces, and issues facing societies in the twenty-first century (such as terrorism and threat detection, medical errors, and the broader implications of automation). Organized into sections representing major areas of theoretical and practical importance for the application of perception psychology to human performance and the design and operation of human-technology interdependence, it also addresses the challenges to basic research, including the problem of quantifying information, defining cognitive resources, and theoretical advances in the nature of attention and perceptual processes.
Dedicated to the memory and work of Lisa Capps, this volume is a forum for scholars and practitioners interested in the typical and atypical development of persons with autism. Each chapter is focused on theoretical considerations and the empirical evidence regarding a specific aspect of functioning, but common themes of development are considered throughout. Within this framework, the contributors provide a detailed and comprehensive account of the development of persons with autism. The book is divided into four sections: (1) Developmental, Neurobiological, Genetic, and Family Considerations; (2) Attention and Perception; (3) Cognition, Theory of Mind, and Executive Functioning; and (4) Social and Adaptive Behaviors. With the consideration of this broad range of topics, this volume is both a state-of-the-art resource about autism and a unique contribution to the study of development. It will be of interest to researchers and care providers from several domains, including psychology, psychiatry, social work, developmental psychology, and education. This volume can be used as a text in graduate and advanced undergraduate courses, and as a resource in applied settings.
Crucially, differences are found between sensitivity to upright and inverted biological motion in both groups (chapters 3, 5, 6 and 7), demonstrating the specificity, validity and reliability of our perceptual measurements. The results of our study demonstrate that - in visual psychophysical tasks - participants with autism show no differences in sensitivity to biological motion and do not recruit alternative perceptual processes.
II. Sensation, Perception & Attention: John Serences (Volume Editor) (Topics covered include taste; visual object recognition; touch; depth perception; motor control; perceptual learning; the interface theory of perception; vestibular, proprioceptive, and haptic contributions to spatial orientation; olfaction; audition; time perception; attention; perception and interactive technology; music perception; multisensory integration; motion perception; vision; perceptual rhythms; perceptual organization; color vision; perception for action; visual search; visual cognition/working memory.)
As the general notion of cognition has recently broadened to include its embodied nature, researchers' accounts of perception have increasingly come to include the body's special status as a window on the world and to accommodate the specific perceptual requirements for identifying, interpreting, and interacting with other bodies. This volume presents a comprehensive overview of the rapid progress that has been made in understanding the human body and its relationship to perception. It will help to unify the relevant research from several independent areas of cognitive psychology and cognitive neuroscience and facilitate the development of an integrated framework for the study of human-body perception.
An accessible introduction to performing meta-analysis across various areas of research The practice of meta-analysis allows researchers to obtain findings from various studies and compile them to verify and form one overall conclusion. Statistical Meta-Analysis with Applications presents the necessary statistical methodologies that allow readers to tackle the four main stages of meta-analysis: problem formulation, data collection, data evaluation, and data analysis and interpretation. Combining the authors' expertise on the topic with a wealth of up-to-date information, this book successfully introduces the essential statistical practices for making thorough and accurate discoveries across a wide array of diverse fields, such as business, public health, biostatistics, and environmental studies. Two main types of statistical analysis serve as the foundation of the methods and techniques: combining tests of effect size and combining estimates of effect size. Additional topics covered include: Meta-analysis regression procedures Multiple-endpoint and multiple-treatment studies The Bayesian approach to meta-analysis Publication bias Vote counting procedures Methods for combining individual tests and combining individual estimates Using meta-analysis to analyze binary and ordinal categorical data Numerous worked-out examples in each chapter provide the reader with a step-by-step understanding of the presented methods. All exercises can be computed using the R and SAS software packages, which are both available via the book's related Web site. Extensive references are also included, outlining additional sources for further study. Requiring only a working knowledge of statistics, Statistical Meta-Analysis with Applications is a valuable supplement for courses in biostatistics, business, public health, and social research at the upper-undergraduate and graduate levels. It is also an excellent reference for applied statisticians working in industry, academia, and government.
The scientific study of the human body has burgeoned in recent years, and scholars from wide-ranging disciplines are now seeking to understand just how much information can be conveyed by the human body in motion. This volume sheds light on the potency of the human body to inform our most basic perceptions of one another.