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Steven M Silverstein - One of the best experts on this subject based on the ideXlab platform.
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comparison of visual Perceptual Organization in schizophrenia and body dysmorphic disorder
Psychiatry Research-neuroimaging, 2015Co-Authors: Steven M Silverstein, Corinna M Elliott, Jamie D Feusner, Brian P Keane, Deepthi Mikkilineni, Natasha S Hansen, Andrea S Hartmann, Sabine WilhelmAbstract:Abstract People with schizophrenia are impaired at organizing potentially ambiguous visual information into well-formed shape and object representations. This Perceptual Organization (PO) impairment has not been found in other psychiatric disorders. However, recent data on body dysmorphic disorder (BDD), suggest that BDD may also be characterized by reduced PO. Similarities between these groups could have implications for understanding the RDoC dimension of visual perception in psychopathology, and for modeling symptom formation across these two conditions. We compared patients with SCZ ( n =24) to those with BDD ( n =20), as well as control groups of obsessive–compulsive disorder (OCD) patients ( n =20) and healthy controls ( n =20), on two measures of PO that have been reliably associated with schizophrenia-related performance impairment. On both the contour integration and Ebbinghaus illusion tests, only the SCZ group demonstrated abnormal performance relative to controls; the BDD group performed similarly to the OCD and CON groups. In addition, on both tasks, the SCZ group performed more abnormally than the BDD group. Overall, these data suggest that PO reductions observed in SCZ are not present in BDD. Visual processing impairments in BDD may arise instead from other Perceptual disturbances or attentional biases related to emotional factors.
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Perceptual Organization impairment in schizophrenia and associated brain mechanisms review of research from 2005 to 2010
Schizophrenia Bulletin, 2011Co-Authors: Steven M Silverstein, Brian P KeaneAbstract:Perceptual Organization (PO) refers to the processes by which visual information is structured into coherent patterns such as groups, contours, Perceptual wholes, and object representations. Impairments in PO have been demonstrated in schizophrenia since the 1960s and have been linked to several illness-related factors including poor premorbid functioning, poor prognosis, and disorganized symptoms. This literature was last reviewed in 2005. Since then, electrophysiological (electroencephalographic, event-related potential, and magnetoencephalographic) and fMRI studies in both patient and nonpatient samples have clarified brain mechanisms involved in the impairment, and additional behavioral studies in patients and nonpatients have clarified the computational mechanisms. In addition, data now exist on the functional consequences of PO impairments, in terms of secondary difficulties in face processing, selective attention, working memory, and social cognition. Preliminary data on drug effects on PO and on changes in response to treatment suggest that anomalies in PO may furnish a biomarker for the integrity of its associated biological mechanisms. All of this recent evidence allows for a clearer picture of the nature of the impairment and how it relates to broader aspects of brain and behavioral functioning in schizophrenia.
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Perceptual Organization and visual search processes during target detection task performance in schizophrenia as revealed by fmri
Neuropsychologia, 2010Co-Authors: Steven M Silverstein, Brian Essex, Sarah Berten, Sherrie D All, Ravi Kasi, Deborah M LittleAbstract:Abstract Background Past studies of Perceptual Organization in schizophrenia have demonstrated impairments binding fragmented stimulus components into unified representations. ERP and fMRI data indicate that even under conditions of adequate behavioral task performance, significant and meaningful changes in cortical and subcortical activation are present. Here, we examined, using fMRI, activation differences on a visual task wherein feature grouping was a precursor to the formation of distinct groups in the service of target location and identification. Method Fourteen schizophrenia patients and 16 healthy controls completed a target detection task with 2 conditions: one in which target–distractor grouping facilitates detection (the Isolated condition) and one in which it hinders detection (the Embedded condition). Stimuli were blocked by condition. Accuracy and RT data were obtained in addition to fMRI data. Results Patients and controls did not differ significantly in accuracy or RT in either condition. Within this context, controls demonstrated greater recruitment of brain regions involved in visual–spatial processing, and the groups differed in activity in areas known to support visual search, visual analysis, decision making and response generation. Conclusion These findings are consistent with past data indicating reduced processing of stimulus Organization, and the subsequent use of inefficient visual search strategies, even under conditions when behavioral performance is at a high level and matches that of healthy controls.
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Perceptual Organization in first episode schizophrenia and ultra high risk states
Schizophrenia Research, 2006Co-Authors: Steven M Silverstein, Peter J Uhlhaas, Brian Essex, Sean A Halpin, Ulrich Schall, Vaughan J CarrAbstract:Deficits in Perceptual Organization have been consistently reported in schizophrenia, as has an association between these deficits, disorganized symptoms, and poorer premorbid functioning and prognosis, suggesting that they may be an index of illness severity or progression. It is unclear, however, whether the impairment is present at, or before the first psychotic episode. This study examined Perceptual Organization in young people considered to be at high-risk for schizophrenia, defined by the "close-in" strategy [Yung, A.R., McGorry, P.D., McFarlane, C.A., Jackson, H.J., Patton, G.C., Rakkar, 1996. Monitoring and care of young people at incipient risk of psychosis. Schizophrenia Bulletin, 22, 283-303]. The high-risk group (n=70) was compared to first-episode patients (n=54), and nonpatients (n=24) using a task with known sensitivity to Perceptual Organization deficits in schizophrenia, and whose scores have predicted long-term outcome and disorganized symptomatology in past studies [Knight, R.A., Silverstein, S.M., 1998. The role of cognitive psychology in guiding research on cognitive deficits in schizophrenia. In Lenzenweger, M., Dworkin, R.H., (Eds.), Origins and Development of Schizophrenia: Advances in Experimental Psychopathology. APA Press, Washington DC, pp. 247-295.; Silverstein, S.M., Knight, R.A., Schwarzkopf, S.B., West, L.L., Osborn, L.M. Kamin, D., 1996b. Stimulus configuration and context effects in Perceptual Organization in schizophrenia. Journal of Abnormal Psychology 105, 410-420.; Silverstein, S.M., Schenkel, L.S., Valone, C., Nuernberger, S., 1998a. Cognitive deficits and psychiatric rehabilitation outcomes in schizophrenia. Psychiatric Quarterly 69, 169-191.; Silverstein, S.M., Bakshi, S., Chapman, R.M., Nowlis, G., 1998b. Perceptual Organization of configural and nonconfigural visual patterns in schizophrenia: effects of repeated exposure. Cognitive Neuropsychiatry 3, 209-223]. There were no differences between groups, and the first-episode group demonstrated non-significantly more sensitivity to stimulus Organization than the other groups. When the high-risk group was broken down into its 3 subgroups (A--family history of psychotic illness and recent drop of 30+ points in the GAF scale; B--history of attenuated psychotic symptoms; C--brief limited intermittent psychotic symptoms), only group A demonstrated evidence of impairment, but this group differed significantly only from first- and young, later-episode schizophrenia patients, not from nonpatients. These findings are consistent with recent data on pre-attentive processes in schizophrenia which indicate that performance is not impaired and may even be enhanced, early in the illness, with dysfunctions beginning with increased chronicity.
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the course and clinical correlates of dysfunctions in visual Perceptual Organization in schizophrenia during the remission of psychotic symptoms
Schizophrenia Research, 2005Co-Authors: Peter J Uhlhaas, William A Phillips, Steven M SilversteinAbstract:This study evaluated deficits in visual Perceptual Organization in schizophrenia over the course of inpatient treatment, in relation to the remission of particular psychotic symptoms. Disorganized (n=14) and non-disorganized (n=33) schizophrenia patients were tested upon admission to an inpatient psychiatric unit, and again after 3 weeks of treatment, on two measures of visual Perceptual Organization. Performance of schizophrenia patients was compared to groups of patients with psychotic disorders other than schizophrenia (n=19) and non-psychotic psychiatric disorders (n=25). Symptom ratings were collected at both assessment points. Deficits in visual Perceptual Organization were observed for both tasks in disorganized schizophrenia patients at index and these deficits improved during the course of treatment. Moreover, improvement in visual Perceptual Organization correlated significantly with reductions in disorganized symptoms in the schizophrenia group. We interpret these data as further support for the hypothesis that the disOrganization syndrome in schizophrenia reflects a widespread deficit in the cognitive coordination of contextually related stimuli, leading to dysfunctional Organization of stimulus features in vision, thought and language.
Johan Wagemans - One of the best experts on this subject based on the ideXlab platform.
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Perceptual Organization in individuals with autism spectrum disorder
Child Development Perspectives, 2018Co-Authors: Kris Evers, Ruth Van Der Hallen, Ilse Noens, Johan WagemansAbstract:Autism spectrum disorder (ASD) is typically associated with problems in social communication and interaction, combined with restrictive and repetitive interests, behaviors, and activities. In addition, individuals with ASD often experience sensory abnormalities and have difficulties with Perceptual Organization, which can affect other aspects of information processing, such as attention, and perception of faces and motion. Researchers have studied atypical Perceptual Organization in individuals with ASD over the past decades, particularly in visual perception, finding both a reduced tendency to integrate information into meaningful wholes and a stronger focus on details in individuals with autism. In this article, we review empirical findings and describe briefly two influential theoretical accounts (weak central coherence and enhanced Perceptual functioning theory), as well as more recent theoretical frameworks that emphasize the imbalance between local and global processing, or anomalies at the level of the brain as an engine of prediction.
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reliability and validity of the leuven Perceptual Organization screening test l post
Journal of Neuropsychology, 2015Co-Authors: Kathleen Vancleef, Johan Wagemans, Elia Acke, Katrien Torfs, Nele Demeyere, Christophe Lafosse, Glyn W Humphreys, Lee DewitAbstract:Neuropsychological tests of visual perception mostly assess high-level processes like object recognition. Object recognition, however, relies on distinct mid-level processes of Perceptual Organization that are only implicitly tested in classical tests. Furthermore, the psychometric properties of the existing instruments are limited. To fill this gap, the Leuven Perceptual Organization screening test (L-POST) was developed, in which a wide range of mid-level phenomena are measured in 15 subtests. In this study, we evaluated reliability and validity of the L-POST. Performance on the test is evaluated relative to a norm sample of more than 1,500 healthy control participants. Cronbach's alpha of the norm sample and test-retest correlations for 20 patients provide evidence for adequate reliability of L-POST performance. The convergent and discriminant validity of the test was assessed in 40 brain-damaged patients, whose performance on the L-POST was compared with standard clinical tests of visual perception and other measures of cognitive function. The L-POST showed high sensitivity to visual dysfunction and decreased performance was specific to visual problems. In conclusion, the L-POST is a reliable and valid screening test for Perceptual Organization. It offers a useful online tool for researchers and clinicians to get a broader overview of the mid-level processes that are preserved or disrupted in a given patient.
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the oxford handbook of Perceptual Organization
2015Co-Authors: Johan WagemansAbstract:SECTION ONE: GENERAL BACKGROUND SECTION TWO: GROUPS, PATTERNS, TEXTURES SECTION THREE: CONTOURS AND SHAPES SECTION FOUR: FIGURE-GROUND Organization SECTION FIVE: SURFACE AND COLOUR PERCEPTION SECTION SIX: MOTION AND EVENT PERCEPTION SECTION SEVEN: Perceptual Organization AND OTHER MODALITIES SECTION EIGHT: SPECIAL INTEREST TOPICS SECTION NINE: APPLICATIONS OF Perceptual Organization SECTION TEN: THEORETICAL APPROACHES
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The Leuven Perceptual Organization Screening Test (L-POST), an online test to assess mid-level visual perception
Behavior Research Methods, 2014Co-Authors: Katrien Torfs, Johan Wagemans, Kathleen Vancleef, Christophe Lafosse, Lee De-witAbstract:Neuropsychological diagnostic tests of visual perception mostly assess high-level processes like object recognition. Object recognition, however, relies on distinct mid-level processes of Perceptual Organization that are only implicitly tested in classical tests. The Leuven Perceptual Organization Screening Test (L-POST) fills a gap with respect to clinically oriented tests of mid-level visual function. In 15 online subtests, a range of mid-level processes are covered, such as figure–ground segmentation, local and global processing, and shape perception. We also test the sensitivity to a wide variety of Perceptual grouping cues, like common fate, collinearity, proximity, and closure. To reduce cognitive load, a matching-to-sample task is used for all subtests. Our online test can be administered in 20–45 min and is freely available at www.gestaltrevision.be/tests . The online implementation enables us to offer a separate interface for researchers and clinicians to have immediate access to the raw and summary results for each patient and to keep a record of their patient’s entire data. Also, each patient’s results can be flexibly compared with a range of age-matched norm samples. In conclusion, the L-POST is a valuable screening test for Perceptual Organization. The test allows clinicians to screen for deficits in visual perception and enables researchers to get a broader overview of mid-level visual processes that are preserved or disrupted in a given patient.
Ruth Kimchi - One of the best experts on this subject based on the ideXlab platform.
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attention enhances apparent Perceptual Organization
Psychonomic Bulletin & Review, 2018Co-Authors: Antoine Barbot, Sirui Liu, Ruth Kimchi, Marisa CarrascoAbstract:Perceptual Organization and selective attention are two crucial processes that influence how we perceive visual information. The former structures complex visual inputs into coherent units, whereas the later selects relevant information. Attention and Perceptual Organization can modulate each other, affecting visual processing and performance in various tasks and conditions. Here, we tested whether attention can alter the way multiple elements appear to be Perceptually organized. We manipulated covert spatial attention using a rapid serial visual presentation task, and measured Perceptual Organization of two multielements arrays organized by luminance similarity as rows or columns, at both the attended and unattended locations. We found that the apparent Perceptual Organization of the multielement arrays is intensified when attended and attenuated when unattended. We ruled out response bias as an alternative explanation. These findings reveal that attention enhances the appearance of Perceptual Organization, a midlevel vision process, altering the way we perceive our visual environment.
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crowding and Perceptual Organization target s objecthood influences the relative strength of part level and configural level crowding
Journal of Vision, 2017Co-Authors: Yossef Pirkner, Ruth KimchiAbstract:In visual crowding, identification of a peripheral object is impaired by nearby objects. Recent studies have demonstrated that crowding is not limited only to interaction between low-level features or parts, as presumed by most models of crowding, but can also occur between high-level, configural representations of objects. In this study we show that the relative strength of crowding at the part level versus the configural level is dependent on the strength of the target's Perceptual Organization. The target's strength of Organization was manipulated by presence or absence of closure and good continuation or by proximity between the target's parts. The flankers were similar either to the target parts or to the target configuration. The stronger the target's Organization was, the weaker the crowding was by part flankers (Experiments 1 and 2). Most importantly, the target's strength of Organization interacted with target-flanker similarity, such that crowding by target-flanker similarity in configuration was greater than that by target-flanker similarity in parts for strongly organized targets, but lesser for weakly organized targets (Experiments 3 and 4). These results provide strong evidence that Perceptual-Organization processes play an important role in crowding.
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Perceptual Organization visual attention and objecthood
Vision Research, 2016Co-Authors: Ruth Kimchi, Yaffa Yeshurun, Branka Spehar, Yossef PirknerAbstract:We have previously demonstrated that the mere Organization of some elements in the visual field into an object attracts attention automatically. Here, we explored three different aspects of this automatic attentional capture: (a) Does the attentional capture by an object involve a spatial component? (b) Which Gestalt Organization factors suffice for an object to capture attention? (c) Does the strength of Organization affect the object's ability to capture attention? Participants viewed multi-elements displays and either identified the color of one element or responded to a Vernier target. On some trials, a subset of the elements grouped by Gestalt factors into an object that was irrelevant to the task and not predictive of the target. An object effect - faster performance for targets within the object than for targets outside the object - was found even when the target appeared after the object offset, and was sensitive to target-object distance, suggesting that the capture of attention by an object is accompanied by a deployment of attention to the object location. Object effects of similar magnitude were found for objects grouped by a combination of factors (collinearity, closure, and symmetry, or closure and symmetry) or by a single factor when it was collinearity, but not symmetry, suggesting that collinearity, or closure combined with symmetry, suffices for automatic capture of attention by an object, but symmetry does not. Finally, the strength of grouping in modal completion, manipulated by varying contrast polarity between and within elements, affected the effectiveness of the attentional capture by the induced object.
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microgenesis and ontogenesis of Perceptual Organization evidence from global and local processing of hierarchical patterns
Psychological Science, 2005Co-Authors: Ruth Kimchi, Marlene Behrmann, Batsheva Hadad, Stephen E PalmerAbstract:In two experiments, visual search and speeded classification were used to study perception of hierarchical patterns among participants aged 5 to 23 years. Perception of global configurations of few-element patterns and local elements of many-element patterns showed large age-related improvements. Only minor age-related changes were observed in perception of global configurations of many-element patterns and local elements of few-element patterns. These results are consistent with prior microgenetic analyses using hierarchical patterns. On the one hand, the rapid and effortless grouping of many small elements and the individuation of few large elements both mature by age 5. In contrast, the time-consuming and effortful grouping of few large elements and the individuation of many small elements improve substantially with age, primarily between ages 5 and 10. These findings support the view that Perceptual Organization involves multiple processes that vary in time course, attentional demands, and development...
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Perceptual Organization in vision behavioral and neural perspectives
2003Co-Authors: Ruth Kimchi, Marlene Behrmann, Carl R OlsonAbstract:Contents: Preface. Part I: Cognitive Approaches to Perceptual Organization. S.E. Palmer, Perceptual Organization and Grouping. M. Kubovy, S. Gepshtein, Perceptual Grouping in Space and in Space-Time: An Exercise in Phenomenological Psychophysics. M.A. Peterson, On Figures, Grounds, and Varieties of Surface Completion. R. Kimchi, Visual Perceptual Organization: A Microgenetic Analysis. P.J. Kellman, Visual Perception of Objects and Boundaries: A Four-Dimensional Approach. Part II: Development and Learning in Perceptual Organization. A. Needham, S.M. Ormsbee, The Development of Object Segregation During the First Year of Life. R.L. Goldstone, Learning to Perceive While Perceiving to Learn. Part III: Neural Approaches to Perceptual Organization. R. von der Heydt, H. Zhou, H.S. Friedman, Neural Coding of Border Ownership: Implications for the Theory of Figure-Ground Perception. T.D. Albright, L.J. Croner, R.O. Duncan, G.R. Stoner, Neuronal Correlates of Perceptual Organization in the Primate Visual System. M. Behrmann, R. Kimchi, Visual Perceptual Organization: Lessons From Lesions. G.W. Humphreys, Binding in Vision as a Multistage Process. Part IV: Computational Approaches to Perceptual Organization. D.W. Jacobs, Perceptual Completion and Memory. T.S. Lee, Neural Basis of Attentive Perceptual Organization.
Peter J Uhlhaas - One of the best experts on this subject based on the ideXlab platform.
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impaired gamma band activity during Perceptual Organization in adults with autism spectrum disorders evidence for dysfunctional network activity in frontal posterior cortices
The Journal of Neuroscience, 2012Co-Authors: Limin Sun, Christine Grutzner, Sven Bolte, Michael Wibral, Tahmine Tozman, Sabine Schlitt, Fritz Poustka, Wolf Singer, Christine M Freitag, Peter J UhlhaasAbstract:Current theories of the pathophysiology of autism spectrum disorders (ASD) have focused on abnormal temporal coordination of neural activity in cortical circuits as a core impairment of the disorder. In the current study, we examined the possibility that gamma-band activity may be crucially involved in aberrant brain functioning in ASD. Magneto-encephalographic (MEG) data were recorded from 13 adult human participants with ASD and 16 controls during the presentation of Mooney faces. MEG data were analyzed in the 25–150 Hz frequency range and a beamforming approach was used to identify the sources of spectral power. Participants with ASD showed elevated reaction times and reduced detection rates during the perception of upright Mooney faces, while responses to inverted stimuli were in the normal range. Impaired Perceptual Organization in the ASD group was accompanied by a reduction in both the amplitude and phase locking of gamma-band activity. A beamforming approach identified distinct networks during Perceptual Organization in controls and participants with ASD. In controls, Perceptual Organization of Mooney faces involved increased 60–120 Hz activity in a frontoparietal network, while in the ASD group stronger activation was found in visual regions. These findings highlight the contribution of impaired gamma-band activity toward complex visual processing in ASD, suggesting atypical modulation of high-frequency power in frontoposterior networks.
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Perceptual Organization in ketamine users preliminary evidence of deficits on night of drug use but not 3 days later
Journal of Psychopharmacology, 2007Co-Authors: Peter J Uhlhaas, Isobel Millard, Leslie Muetzelfeldt, Valerie H Curran, Celia J A MorganAbstract:N-methyl-D-aspartate (NMDA)-receptor antagonists such as ketamine can induce transient schizophrenia-like symptoms and cognitive dysfunctions in healthy voLunteers similar to those observed in patients with schizophrenia. Perceptual Organization deficits have been documented in schizophrenia and are thought to be related to some symptoms associated with the illness. The current study was designed to determine whether people who repeatedly self-administer ketamine would also show deficits in Perceptual Organization. Using a psychophysically well-controlled measure of contour integration, we compared a group of recreational users (n = 16) to a group of poly-drug using controls (n = 16). Contour integration performance was measured on the night of drug use and 3 days later when drug free. The results showed that on the night of drug use, ketamine produced a dysfunction in contour integration however, this was not present 3 days Later when drug free. Levels of dissociation were also higher in ketamine users o...
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Perceptual Organization in first episode schizophrenia and ultra high risk states
Schizophrenia Research, 2006Co-Authors: Steven M Silverstein, Peter J Uhlhaas, Brian Essex, Sean A Halpin, Ulrich Schall, Vaughan J CarrAbstract:Deficits in Perceptual Organization have been consistently reported in schizophrenia, as has an association between these deficits, disorganized symptoms, and poorer premorbid functioning and prognosis, suggesting that they may be an index of illness severity or progression. It is unclear, however, whether the impairment is present at, or before the first psychotic episode. This study examined Perceptual Organization in young people considered to be at high-risk for schizophrenia, defined by the "close-in" strategy [Yung, A.R., McGorry, P.D., McFarlane, C.A., Jackson, H.J., Patton, G.C., Rakkar, 1996. Monitoring and care of young people at incipient risk of psychosis. Schizophrenia Bulletin, 22, 283-303]. The high-risk group (n=70) was compared to first-episode patients (n=54), and nonpatients (n=24) using a task with known sensitivity to Perceptual Organization deficits in schizophrenia, and whose scores have predicted long-term outcome and disorganized symptomatology in past studies [Knight, R.A., Silverstein, S.M., 1998. The role of cognitive psychology in guiding research on cognitive deficits in schizophrenia. In Lenzenweger, M., Dworkin, R.H., (Eds.), Origins and Development of Schizophrenia: Advances in Experimental Psychopathology. APA Press, Washington DC, pp. 247-295.; Silverstein, S.M., Knight, R.A., Schwarzkopf, S.B., West, L.L., Osborn, L.M. Kamin, D., 1996b. Stimulus configuration and context effects in Perceptual Organization in schizophrenia. Journal of Abnormal Psychology 105, 410-420.; Silverstein, S.M., Schenkel, L.S., Valone, C., Nuernberger, S., 1998a. Cognitive deficits and psychiatric rehabilitation outcomes in schizophrenia. Psychiatric Quarterly 69, 169-191.; Silverstein, S.M., Bakshi, S., Chapman, R.M., Nowlis, G., 1998b. Perceptual Organization of configural and nonconfigural visual patterns in schizophrenia: effects of repeated exposure. Cognitive Neuropsychiatry 3, 209-223]. There were no differences between groups, and the first-episode group demonstrated non-significantly more sensitivity to stimulus Organization than the other groups. When the high-risk group was broken down into its 3 subgroups (A--family history of psychotic illness and recent drop of 30+ points in the GAF scale; B--history of attenuated psychotic symptoms; C--brief limited intermittent psychotic symptoms), only group A demonstrated evidence of impairment, but this group differed significantly only from first- and young, later-episode schizophrenia patients, not from nonpatients. These findings are consistent with recent data on pre-attentive processes in schizophrenia which indicate that performance is not impaired and may even be enhanced, early in the illness, with dysfunctions beginning with increased chronicity.
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the course and clinical correlates of dysfunctions in visual Perceptual Organization in schizophrenia during the remission of psychotic symptoms
Schizophrenia Research, 2005Co-Authors: Peter J Uhlhaas, William A Phillips, Steven M SilversteinAbstract:This study evaluated deficits in visual Perceptual Organization in schizophrenia over the course of inpatient treatment, in relation to the remission of particular psychotic symptoms. Disorganized (n=14) and non-disorganized (n=33) schizophrenia patients were tested upon admission to an inpatient psychiatric unit, and again after 3 weeks of treatment, on two measures of visual Perceptual Organization. Performance of schizophrenia patients was compared to groups of patients with psychotic disorders other than schizophrenia (n=19) and non-psychotic psychiatric disorders (n=25). Symptom ratings were collected at both assessment points. Deficits in visual Perceptual Organization were observed for both tasks in disorganized schizophrenia patients at index and these deficits improved during the course of treatment. Moreover, improvement in visual Perceptual Organization correlated significantly with reductions in disorganized symptoms in the schizophrenia group. We interpret these data as further support for the hypothesis that the disOrganization syndrome in schizophrenia reflects a widespread deficit in the cognitive coordination of contextually related stimuli, leading to dysfunctional Organization of stimulus features in vision, thought and language.
David P Salmon - One of the best experts on this subject based on the ideXlab platform.
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visual Perceptual Organization ability in autopsy verified dementia with lewy bodies and alzheimer s disease
Journal of The International Neuropsychological Society, 2016Co-Authors: Micaela Mitolo, Joanne M Hamilton, Kelly M Landy, Lawrence A Hansen, Douglas Galasko, Francesca Pazzaglia, David P SalmonAbstract:Objectives: Prominent impairment of visuospatial processing is a feature of dementia with Lewy bodies (DLB), and diagnosis of this impairment may help clinically distinguish DLB from Alzheimer’s disease (AD). The current study compared autopsy-confirmed DLB and AD patients on the Hooper Visual Organization Test (VOT), a test that requires Perceptual and mental reOrganization of parts of an object into an identifiable whole. The VOT may be particularly sensitive to DLB since it involves integration of visual information processed in separate dorsal and ventral visual “streams”. Methods: Demographically similar DLB (n=28), AD (n=115), and normal control (NC; n=85) participants were compared on the VOT and additional neuropsychological tests. Patient groups did not differ in dementia severity at time of VOT testing. High and Low AD-Braak stage DLB subgroups were compared to examine the influence of concomitant AD pathology on VOT performance. Results: Both patient groups were impaired compared to NC participants. VOT scores of DLB patients were significantly lower than those of AD patients. The diagnostic sensitivity and specificity of the VOT for patients versus controls was good, but marginal for DLB versus AD. High-Braak and low-Braak DLB patients did not differ on the VOT, but High-Braak DLB performed worse than Low-Braak DLB on tests of episodic memory and language. Conclusions: Visual Perceptual Organization ability is more impaired in DLB than AD but not strongly diagnostic. The disproportionate severity of this visual Perceptual deficit in DLB is not related to degree of concomitant AD pathology, which suggests that it might primarily reflect Lewy body pathology. (JINS, 2016, 22, 609–619)
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deterioration of visual Perceptual Organization ability in alzheimer s disease
Cortex, 2007Co-Authors: Jessica L Paxton, Guerry M Peavy, Cecily Jenkins, Valerie A Rice, William C Heindel, David P SalmonAbstract:Although deterioration of higher-order visual information processing abilities occurs in Alzheimer's disease (AD), few cross-sectional or longitudinal studies have systematically examined this deficit. The performance of 135 patients with probable AD and 97 matched normal control (NC) participants were compared on a structured test of Perceptual Organization ability, the Hooper Visual Organization Test (VOT). Both the standard VOT score and a derived score that corrected for anomia were significantly lower for AD patients than for NC participants, but neither score was particularly effective at distinguishing between the groups. The derived VOT score proved to be a more effective measure of visuospatial functioning than the standard VOT score as it loaded with other visuospatial tests in a principal components analysis while the standard score loaded with language tests. The VOT was sensitive to severity of dementia in the AD patients. Longitudinal assessment of 37 of the AD patients and 46 NC participants revealed significant decline over one year in the VOT scores of AD patients, but not in those of NC participants. These results indicate that higher-order visual information processing is impaired in patients with AD and gradually deteriorates with disease progression. This deficit may not be a particularly salient early marker of the disease, but it may be useful in tracking disease course.
