Statistical and adaptive signal processing for UXO discrimination for next-generation sensor data

Abstract-Until recently, detection algorithms could not reliably distinguish between buried UXO and clutter, leading to many false alarms. Over the last several years modern geophysical techniques have been developed that merge more sophisticated sensors, underlying physical models, statistical signal processing algorithms, and adaptive training techniques. These new approaches have dramatically reduced false alarm rates, although for the most part they have been applied to data collected at sites with relatively benign topology and anomaly densities. On more challenging sites, performance of even these more modern discrimination approaches is still quite poor. As a result, efforts are underway to develop a new generation of UXO sensors that will produce data streams of multi-axis vector or gradiometric measurements, for which optimal processing has not yet been carefully considered or developed. We describe a research program to address this processing gap, employing a synergistic use of advanced phenomenologicalmodeling and signal-processing algorithms. The key foci of the program are (1) development of new physics-based signal processing approaches applicable to the problem in which vector data is available from such sensors; and (2) development of the theory of optimal experiments to guide the optimal design and deployment of the new sensor modalities. Here, we present initial results using simulated data obtained with our phenomenological models that indicate that optimal processing of features extracted from multi-axis EMI data can provide substantial improvements in discrimination performance over processing of features extracted from single-axis data

Do children with autism perceive second-order relational features? The case of the Thatcher illusion

Background:This study presents two experiments that investigated whether children with autism were susceptible to the Thatcher illusion. Perception of the Thatcher illusion requires being able to compute second-order configural relations for facial stimuli. Method:In both experiments children with autism were matched for non-verbal and verbal ability with a group of children with moderate (non-specific) mental retardation (MLD) and a group of typically developing children respectively. Participants were asked to detect the ‘unusual’ face in a two-alternative-forced-choice version of the Margaret Thatcher illusion with grey-scale (Experiment 1) and monochrome ‘Mooney’ face images (Experiment 2). In Experiment 1 participants also performed a control task where buildings had been doctored in the same way as the facial stimuli. Results:Children with autism were as susceptible to the Thatcher illusion as both control groups, in terms of accuracy and reaction time to make decisions about which face was unusual. Children with autism performed more accurately than children with MLD in the buildings task. Conclusion:Children with autism are able to compute second-order configural features in faces and exhibit no difference in face processing, relative to appropriate control groups