Visual Perceptual Organization Research Articles

Dorsal attention network activity during perceptual organization is distinct in schizophrenia and predictive of cognitive disorganization.

Visual shape completion is a canonical perceptual organization process that integrates spatially distributed edge information into unified representations of objects. People with schizophrenia show difficulty in discriminating completed shapes, but the brain networks and functional connections underlying this perceptual difference remain poorly understood. Also unclear is whether brain network differences in schizophrenia occur in related illnesses or vary with illness features transdiagnostically. To address these topics, we scanned (functional magnetic resonance imaging, fMRI) people with schizophrenia, bipolar disorder, or no psychiatric illness during rest and during a task in which they discriminated configurations that formed or failed to form completed shapes (illusory and fragmented condition, respectively). Multivariate pattern differences were identified on the cortical surface using 360 predefined parcels and 12 functional networks composed of such parcels. Brain activity flow mapping was used to evaluate the likely involvement of resting-state connections for shape completion. Illusory/fragmented task activation differences ('modulations') in the dorsal attention network (DAN) could distinguish people with schizophrenia from the other groups (AUCs > .85) and could transdiagnostically predict cognitive disorganization severity. Activity flow over functional connections from the DAN could predict secondary visual network modulations in each group, except in schizophrenia. The secondary visual network was strongly and similarly modulated in each group. Task modulations were dispersed over more networks in patients compared to controls. In summary, DAN activity during visual perceptual organization is distinct in schizophrenia, symptomatically relevant, and potentially related to improper attention-related feedback into secondary visual areas.

Progressive attenuation of visual global precedence across healthy aging and Alzheimer's disease.

In the perception of Navon hierarchical stimuli (e.g., large letters made up of small letters), young adults identify large letters faster than small ones (known as ‘global advantage’) and identify more slowly small letters when they form a different (or incongruent) large letter (known as ‘unidirectional global interference’). Since some global/local perceptual alterations might be occurring with aging, we investigated whether these effects vary across healthy aging and Alzheimer’s disease (AD). Here, the Navon letter task was administered to 26 healthy elderly (HE), 21 adults with mild cognitive impairment (MCI), and 26 adults with AD. The same task was administered 1 year later, and different neuropsychological variables were incorporated into the analyses. The cross-sectional study revealed no global advantage but did reveal both global and local interferences in all groups when response times were analyzed. Regarding discrimination sensitivity, HE showed unidirectional global interference, while AD displayed better discrimination of local than global letters in the incongruent condition, which denotes less interference by global distractors than by local ones. The longitudinal study revealed that 1 year later the participants with MCI showed a slowdown in inhibiting local distractors in the global task, revealing a certain bias toward focus in their attention on small stimuli. The elders with AD reflected a generalized slowing of their responses with a clear bias toward local analysis of stimuli, also suggested by their better discrimination in the incongruent local task at the second moment of assessment. Furthermore, all response timing measures in the Navon task were correlated with several neuropsychological indexes of highly sensitive neuropsychological tests, suggesting that performance in this task may also have a potential diagnostic value for differentiating typical from atypical cognitive aging. All these results support the need for a multidomain approach to define neuropsychological markers of progression toward AD, including visual perceptual organization evaluated via measures of performance quality.

Face pareidolia in schizophrenia

BackgroundFaces convey valuable daily life social signals. As in most psychiatric conditions, non-verbal social cognition or its components including face processing may be aberrant in schizophrenia (SZ). Social participation of individuals with SZ is vital for their quality of life, and remediation of social abilities in this population is of high relevance both for society and clinical care. MethodTuning to faces in non-face images such as shadows, grilled toasts, or ink blots is called face pareidolia. Humans possess high sensitivity to facial signals: even fetuses and infants are well tuned to coarse face cues. Here we assessed face tuning in individuals with SZ and person-by-person matched controls by using a new experimental tool, a set of food-plate images bordering on the Giuseppe Arcimboldo style. The key benefit of these images is that single components do not trigger face processing. Results and conclusionsThe outcome indicates that individuals with SZ exhibit aberrant face tuning in face-like non-face images (χ2(1) = 17.44, p = 0.0001) that can hamper adaptive interaction with peers and social participation hindering, in turn, clinical remediation. Face response rate in SZ patients was related to the scores on the event arrangement task tapping social cognition (Pearson product-moment correlation, r = 0.602, p = 0.01) and on picture completion task assessing visual perceptual organization (Spearman's rho = 0.614, p = 0.009). Therefore, poor performance on the face tuning task is unlikely to be accounted for by deviant general cognitive abilities, but rather by impairments in perceptual integration and social cognition. Comparison of these findings with data in autism and other neuropsychiatric conditions provides novel insights on the origins of face tuning in SZ and triggers brain imaging research.

On Bayesian Simplicity in Human Visual Perceptual Organization

A returning idea among some Bayesians in research on human visual perceptual organization is that the surprisal of something (i.e., the negative logarithm of its probability) expresses its complexity (i.e., the length of its shortest description). Bayes' rule is a powerful modeling tool and descriptive simplicity is a rich concept, but this idea is wishful thinking at best: If true, it would unify the simplicity and likelihood principles, which reflect two traditionally opposed schools of thought on perceptual organization. Some rapprochement between the two principles can certainly be discerned, but the aforementioned idea lacks formal underpinning and confounds otherwise perfectly good ideas. Here, this idea is revisited and its latest version is debunked step by step. In addition, I argue that its likely origin lies, inadvertently, in a standard Bayesian textbook: The author made (a) a pivotal mistake and (b) a compelling argument that was overinterpreted by others.

Human visual perceptual organization beats thinking on speed.

What is the degree to which knowledge influences visual perceptual processes? This question, which is central to the seeing-versus-thinking debate in cognitive science, is often discussed using examples claimed to be proof of one stance or another. It has, however, also been muddled by the usage of different and unclear definitions of perception. Here, for the well-defined process of perceptual organization, I argue that including speed (or efficiency) into the equation opens a new perspective on the limits of top-down influences of thinking on seeing. While the input of the perceptual organization process may be modifiable and its output enrichable, the process itself seems so fast (or efficient) that thinking hardly has time to intrude and is effective mostly after the fact.

Perceptual organization deficits in traumatic brain injury patients

Traumatic brain injury (TBI) is a prevalent condition and there is limited visual perception research with this population. Here, we investigated perceptual organization changes in a rather homogeneous sample of closed head TBI outpatients with diffuse axonal injury only and no other known comorbidities. Patients had normal or corrected visual acuity. Perceptual organization was measured with the Leuven Perceptual Organization Screening Test (L-POST), a coherent motion task (CM) and the Leuven Embedded Figures Test (L-EFT). These tests were chosen to screen for deficits in different aspects of perceptual organization (L-POST), to evaluate local and global processing (L-EFT) and grouping in a dynamic set of stimuli (CM). TBI patients were significantly impaired compared to controls in all measures for both response time and accuracy, except for CM thresholds and object recognition subtests. The TBI group was similarly affected in all aspects of the L-EFT. TBI was also similarly affected in all perceptual factors of the L-POST. No significant correlations were found between scores and time post-injury, except for CM thresholds (rs=−0.74), which might explain the lack of group-level differences. The only score significantly correlated to IQ was L-EFT response time (rs=−0.67). These findings demonstrate that perceptual organization is diffusely affected in TBI and this effect has no substantial correlations with IQ. As many of the neuropsychological tests used to measure different cognitive functions involve some level of visual discrimination and perceptual organization demands, these results must be taken into account in the general neuropsychological evaluation of TBI patients.

Comparison of visual perceptual organization in schizophrenia and body dysmorphic disorder

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.

Transparallel mind: classical computing with quantum power

Inspired by the extraordinary computing power promised by quantum computers, the quantum mind hypothesis postulated that quantum mechanical phenomena are the source of neuronal synchronization, which, in turn, might underlie consciousness. Here, I present an alternative inspired by a classical computing method with quantum power. This method relies on special distributed representations called hyperstrings. Hyperstrings are superpositions of up to an exponential number of strings, which -- by a single-processor classical computer -- can be evaluated in a transparallel fashion, that is, simultaneously as if only one string were concerned. Building on a neurally plausible model of human visual perceptual organization, in which hyperstrings are formal counterparts of transient neural assemblies, I postulate that synchronization in such assemblies is a manifestation of transparallel information processing. This accounts for the high combinatorial capacity and speed of human visual perceptual organization and strengthens ideas that self-organizing cognitive architecture bridges the gap between neurons and consciousness.

Hierarchical Classes Analysis (HICLAS): A novel data reduction method to examine associations between biallelic SNPs and perceptual organization phenotypes in schizophrenia

The power of SNP association studies to detect valid relationships with clinical phenotypes in schizophrenia is largely limited by the number of SNPs selected and non-specificity of phenotypes. To address this, we first assessed performance on two visual perceptual organization tasks designed to avoid many generalized deficit confounds, Kanizsa shape perception and contour integration, in a schizophrenia patient sample. Then, to reduce the total number of candidate SNPs analyzed in association with perceptual organization phenotypes, we employed a two-stage strategy: first a priori SNPs from three candidate genes were selected (GAD1, NRG1 and DTNBP1); then a Hierarchical Classes Analysis (HICLAS) was performed to reduce the total number of SNPs, based on statistically related SNP clusters. HICLAS reduced the total number of candidate SNPs for subsequent phenotype association analyses from 6 to 3. MANCOVAs indicated that rs10503929 and rs1978340 were associated with the Kanizsa shape perception filling in metric but not the global shape detection metric. rs10503929 was also associated with altered contour integration performance. SNPs not selected by the HICLAS model were unrelated to perceptual phenotype indices. While the contribution of candidate SNPs to perceptual impairments requires further clarification, this study reports the first application of HICLAS as a hypothesis-independent mathematical method for SNP data reduction. HICLAS may be useful for future larger scale genotype-phenotype association studies.

Sex, symptom, and premorbid social functioning associated with perceptual organization dysfunction in schizophrenia.

Impairments in visual perceptual organization abilities are a repeatedly observed cognitive deficit in schizophrenia. These impairments have been found to be most prominent among patients with histories of poor premorbid social functioning, disorganized symptoms, and poor clinical outcomes. Despite the demonstration of significant sex differences for these clinical factors in schizophrenia, the extent of sex differences for visual perceptual organization in schizophrenia is unknown. Therefore, we investigated the extent to which previously known correlates (premorbid social sexual functioning and disorganized symptoms) and a novel factor (participant sex) accounted for performance on two perceptual organization tasks (contour integration and Ebbinghaus illusion) that have previously demonstrated sensitivity to schizophrenia. We also determined the relative degree to which each of these factors predicted task scores over and above the others. Schizophrenia patients (N = 109, 43 females) from different levels of care were ascertained. Female patients demonstrated higher contour integration scores, but lower performance on the context sensitivity index of the Ebbinghaus illusion, compared to males. Contour integration performance was significantly associated with poorer premorbid adolescent social sexual functioning and higher levels of disorganized symptoms, supporting past results that indicate a relationship among poor premorbid social sexual functioning, disorganized symptoms, and visual perceptual abnormalities in schizophrenia. However, analyses of Ebbinghaus illusion performance suggests there is a complex relationship among patient sex, clinical factors and perceptual abilities with relatively intact bottom–up grouping processes in females, but greater problems, compared to males with more top–down mediated context sensitivity. Therefore, sex differences may be an important consideration for future studies of visual perceptual organization in schizophrenia.

The McCollough Effect and Facial Emotion Discrimination in Patients With Schizophrenia and Their Unaffected Relatives

Abnormalities in visual processing have been found consistently in schizophrenia patients, including deficits in early visual processing, perceptual organization, and facial emotion recognition. There is however no consensus as to whether these abnormalities represent heritable illness traits and what their contribution is to psychopathology. Fifty patients with schizophrenia, 61 of their first-degree healthy relatives, and 50 psychiatrically healthy volunteers were tested with regard to facial affect (FA) discrimination and susceptibility to develop the color-contingent illusion [the McCollough Effect (ME)]. Both patients and relatives demonstrated significantly lower accuracy in FA discrimination compared with controls. There was also a significant effect of familiality: Participants from the same families had more similar accuracy scores than those who belonged to different families. Experiments with the ME showed that schizophrenia patients required longer time to develop the illusion than relatives and controls, which indicated poor visual adaptation in schizophrenia. Relatives were marginally slower than controls. There was no significant association between the measures of FA discrimination accuracy and ME in any of the participant groups. Facial emotion discrimination was associated with the degree of interpersonal problems, as measured by the Schizotypal Personality Questionnaire in relatives and healthy volunteers, whereas the ME was associated with the perceptual-cognitive symptoms of schizotypy and positive symptoms of schizophrenia. Our results support the heritability of FA discrimination deficits as a trait and indicate visual adaptation abnormalities in schizophrenia, which are symptom related.

Perceptual Organization Without Perception

A critical step in visual perceptual processing is integrating local visual elements into contours so that shapes can be derived from them. It is often assumed that contour integration may reflect hardwired coding of low-level visual features. In this study, we present novel evidence indicating that integration of local elements into contours can be learned subliminally, despite being irrelevant to the training task and despite the local properties of the display varying randomly during training. Learning occurred only when contours were consistently paired with task-relevant targets—echoing the findings of previous studies on subliminal learning of low-level features. Our data indicate that task-irrelevant, exposure-based learning extends beyond local low-level visual features and may play a critical role at multiple levels of visual perceptual organization.

Visual perceptual organization in adults with autism

Visual perceptual organization in adults with autism

Relationships between ophthalmological and neuropaediatric findings in children adopted from Eastern Europe

This study aimed to evaluate and relate visual function, ocular dimensions and neuropaediatric findings in adoptees from Eastern Europe. We studied 72 of 99 children, born during 1990-95 and adopted from Eastern Europe to western Sweden during 1993-97. The children (mean age 7.5 years, range 4.8-10.5 years; 41 boys, 31 girls) were examined after a mean period of 5 years post-adoption by a multidisciplinary team. Correlations between ophthalmological findings and neuropaediatric data were analysed. Bivariate and regression analyses indicate a significant positive correlation between visual acuity (VA) and perceptual organization (p < 0.001), as well as between strabismus and verbal comprehension (p < 0.02). Fetal alcohol syndrome (FAS) was correlated with low VA (p < 0.02), subnormal stereovision (p < 0.009) and small optic discs (p < 0.02). Small head circumference was related to low VA (p < 0.015) and small optic discs (p < 0.03). Furthermore, small optic discs were related to low birthweight (p < 0.005) and preterm birth (p < 0.01). Large optic cups were correlated with poorer perceptual organization (p < 0.02). In this group of adoptees from Eastern Europe, ophthalmological findings were correlated to neuropaediatric findings, especially those arising from prenatal adverse events resulting in growth deficiency and central nervous system damage. Therefore, it is important and valuable with an ophthalmological examination in children adopted from Eastern Europe.

Visual Perceptual Organization Deficits in Alzheimer’s Dementia

Background: Deficits in visual processing are a prominent feature of Alzheimer’s disease (AD), yet the cognitive and neuropathological mechanisms underlying these deficits are poorly understood. In the current study, we examined the hypothesis that perceptual organization is specifically impaired in AD compared to other dementias. Methods: We examined perceptual organization with a psychophysically well-controlled measure of contour integration in patients with AD (n = 17), vascular dementia (n = 5), frontotemporal dementia (n = 5) and mild cognitive impairment (n = 10) and 11 age-matched healthy controls. Results: Patients with AD differed significantly in their ability to detect contours comprised of Gabor elements as detection relied increasingly on long-range spatial interactions. Impairments in contour integration were particularly pronounced in AD patients with atrophy and gliosis of white matter in the occipital lobe. Deficits in perceptual organization were not found in patients with other dementias and participants with mild cognitive impairment. Conclusions: These results suggest that a subgroup of AD patients is characterized by a specific deficit in visual perceptual organization, which might reflect the impaired functional integrity of occipital cortico-cortical pathways.

Deterioration of Visual-Perceptual Organization Ability in Alzheimer's Disease

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.

Temporal Dynamics of Auditory and Visual Bistability Reveal Common Principles of Perceptual Organization

When dealing with natural scenes, sensory systems have to process an often messy and ambiguous flow of information. A stable perceptual organization nevertheless has to be achieved in order to guide behavior. The neural mechanisms involved can be highlighted by intrinsically ambiguous situations. In such cases, bistable perception occurs: distinct interpretations of the unchanging stimulus alternate spontaneously in the mind of the observer. Bistable stimuli have been used extensively for more than two centuries to study visual perception. Here we demonstrate that bistable perception also occurs in the auditory modality. We compared the temporal dynamics of percept alternations observed during auditory streaming with those observed for visual plaids and the susceptibilities of both modalities to volitional control. Strong similarities indicate that auditory and visual alternations share common principles of perceptual bistability. The absence of correlation across modalities for subject-specific biases, however, suggests that these common principles are implemented at least partly independently across sensory modalities. We propose that visual and auditory perceptual organization could rely on distributed but functionally similar neural competition mechanisms aimed at resolving sensory ambiguities.

Histories of childhood maltreatment in schizophrenia: Relationships with premorbid functioning, symptomatology, and cognitive deficits

A number of studies have demonstrated an increased rate of histories of childhood maltreatment among adults with serious mental illness. The present investigation documented the presence of childhood maltreatment in a sample of 40 psychiatric inpatients with schizophrenia spectrum disorders. The type (neglect, physical abuse, sexual abuse), duration, and severity of childhood maltreatment was examined along with measures of premorbid functioning, current symptomatology, and cognitive functioning. Participants with histories of maltreatment were significantly more likely to have poorer peer relationships in childhood, more difficulty in school, an earlier age at first hospitalization, more previous hospitalizations, elevated symptoms of anxiety, depression, and suicidality on the Brief Psychiatric Rating Scale (BPRS), and more impaired performance on a task of visual–perceptual organization. Severity and frequency of childhood maltreatment were both positively correlated with hallucinations and delusions on the BPRS. Linear trend analysis indicated a pattern of more severe impairment as the number of types of maltreatment increased. No relationships were found between maltreatment and measures of executive functioning, verbal fluency, or verbal processing speed. A history of childhood maltreatment appears to be a significant determinant of premorbid functioning, illness-related symptom expression, and specific forms of cognitive dysfunction.

NEUROPSYCHOLOGICAL MEASURES AND SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY IN THE DIFFERENTIATION AND CLASSIFICATION OF CEREBRAL PERFUSION DEFICITS IN ALZHEIMER'S DEMENTIA

The accurate diagnosis of Dementia of the Alzheimer's Type (DAT) continues to be an area of difficulty for the fields of neuropsychology and neurology. The introduction of new medications that appear to mediate the insidious progression of the disorder increases the need for timely differentiation of DAT from other dementia-related disorders. The present study examined the relationship between hemispheric differences in regional cerebral blood flow with corresponding lateral neuropsychological processing deficits in patients with DAT. Eighty patients with a diagnosis of DAT were administered Single Photon Emission Computerized Tomography (SPECT) scans and a battery of left and right hemisphere neuropsychological-based tasks. The results of ANOVA indicated that patients with DAT who were not suffering from perfusion deficits exhibited significantly fewer neuropsychological deficits than did patients with DAT who had perfusion deficits. The neuropsychological tests that measured verbal ability, logical memory, word-pair learning, reading, arithmetic, and visual-perceptual organization were all significantly lower in the group with perfusion deficits. Further analysis indicated that patients with left hemisphere perfusion deficits tended to have poorer neuropsychological skills than did individuals with right hemisphere perfusion deficits, diffuse perfusion deficits, and no perfusion deficits. A Stepwise Discriminant Analysis was unable to use the neuropsychological variables to classify patients accurately into perfusion deficit groups.

The course and clinical correlates of dysfunctions in visual perceptual organization in schizophrenia during the remission of psychotic symptoms

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.