Shape descriptors and statistical classification on areal topography data for tile inspection in tessellated surfaces

Verification of conformance to design specifications in production, and identification of defects related to wear or other damage during maintenance, are key metrological aspects that must be addressed for micro-scale tessellated surfaces. A new algorithmic approach is presented that operates on topography datasets as obtained by areal topography instruments. The approach combines segmentation algorithms with a novel implementation of the angular radial transform, originally adopted by the MPEG-7 standard, to implement shape descriptors and associated similarity metrics. Applications to the inspection and verification of laser-manufactured micro-embossing topographies are illustrated. The topographies are first segmented to extract the individual tiles; the tiles are then encoded through shape descriptors. Principal component analysis and cluster analysis are used to investigate the behaviour of the angular radial transform coefficients. Finally, an algorithmic classifier based on supervised learning (k-nearest neighbours) is implemented and shown to be effective at identifying defects and at discriminating between defect types

The normalities and abnormalities associated with speech in psychometrically-defined schizotypy

Speech deficits are thought to be an important feature of schizotypy – defined as the personality organization reflecting a putative liability for schizophrenia. There is reason to suspect that these deficits manifest as a function of limited cognitive resources. To evaluate this idea, we examined speech from individuals with psychometrically-defined schizotypy during a low cognitively-demanding task versus a relatively high cognitively-demanding task. A range of objective, computer-based measures of speech tapping speech production (silence, number and length of pauses, number and length of utterances), speech variability (global and local intonation and emphasis) and speech content (word fillers, idea density) were employed. Data for control (n=37) and schizotypy (n=39) groups were examined. Results did not confirm our hypotheses. While the cognitive-load task reduced speech expressivity for subjects as a group for most variables, the schizotypy group was not more pathological in speech characteristics compared to the control group. Interestingly, some aspects of speech in schizotypal versus control subjects were healthier under high cognitive load. Moreover, schizotypal subjects performed better, at a trend level, than controls on the cognitively demanding task. These findings hold important implications for our understanding of the neurocognitive architecture associated with the schizophrenia-spectrum. Of particular note concerns the apparent mismatch between self-reported schizotypal traits and objective performance, and the resiliency of speech under cognitive stress in persons with high levels of schizotypy

The paradox of schizotypy: Resemblance to prolonged severe mental illness in subjective but not objective quality of life

An interesting paradox has emerged regarding the schizophrenia-spectrum. Put simply, college students with schizotypy (defined as the personality organization reflecting a vulnerability to schizophrenia-spectrum pathology) report experiencing pathology with respect to some key functional domains on a level that is equal to or more severe than older, outpatients with an prolonged psychiatric disorders. Notably, this self-reported pathology is not supported by objective/behavioral performance data, suggesting that the primary deficit is psychological in nature (e.g., metacognition). We evaluated whether this subjective-objective dysjunction extends to quality of life (QOL). Eighty-three college students with schizotypy were compared to 50 outpatients with severe mental illness (SMI) as well as to 82 undergraduate and 34 community control groups in subjective and objective QOL via a modified version of Lehman’s Quality of Life Interview, which covers a range of QOL domains. The schizotypy and SMI group were equally impoverished in all measures of subjective QOL compared to the college and community control groups. In contrast, the schizotypy group was relatively normal in most measures of objective quality of life compared to the SMI group. The subjective-objective dysjunction appears to extend to QOL, and these differences do not appear to reflect a more global negativistic reporting bias

Illusory superiority and schizotypal personality: Explaining the discrepancy between subjective/objective psychopathology

An interesting paradox has emerged from the literature regarding schizotypy – defined as the personality organization reflecting a putative liability for schizophrenia-spectrum disorders. Across certain cognitive, emotional, quality of life and other functional variables, individuals with schizotypy report experiencing relatively severe levels of pathology. However, on objective tests of these same variables, individuals with schizotypy perform largely in the healthy range. These subjective impairments are paradoxical in that individuals with schizotypy, typically recruited from undergraduate college populations, should be healthier in virtually every conceivable measure compared to chronic, older outpatients with severe mental illness. The present study evaluated the idea that the subjective deficits associated with schizotypy largely reflect a lack of illusory superiority bias – a normally occurring bias associated with an overestimation of self-reported positive qualities and underestimation of negative qualities compared to others. In the present study, both state – measured using laboratory emotion-induction methods – and trait positive and negative emotion was assessed across self (e.g., “how do you feel at this moment”) and other (e.g., “how do most people feel at this moment”) domains in 39 individuals with self-reported schizotypy and 39 matched controls. Controls demonstrated an illusory superiority effect across both state and trait measures whereas individuals with schizotypy did not. These results were not explained by severity of mental health symptoms. These results suggest that a cognitive bias, or lack thereof, is a marker of schizotypy and a potential target for further research and therapy