Visual Perceptual Organization Research Articles

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.

Object-based visual selective attention and perceptual organization.

We report the results of four experiments that were conducted to examine both the representations that provide candidate entities available for object-based attentional selection and the influence of bottom-up factors (i.e., geometric and surface characteristics of objects) and top-down factors (i.e., context and expectancies) on the selection process. Subjects performed the same task in each of the experiments. They were asked to determine whether two target properties, a bent end and an open end of a wrench, appeared in a brief display of two wrenches. In each experiment, the target properties could occur on a single wrench or one property could occur on each of two wrenches. The question of central interest was whether a same-object effect (faster and/or more accurate performance when the target properties appeared on one vs. two wrenches) would be observed in different experimental conditions. Several interesting results were obtained. First, depending on the geometric (i.e., concave discontinuities on object contours) and surface characteristics (i.e., homogeneous regions of color and texture) of the stimuli, attention was preferentially directed to one of three representational levels, as indicated by the presence or absence of the same-object effect. Second, although geometric and surface characteristics defined the candidate objects available for attentional selection, top-down factors were quite influential in determining which representational level would be selected. Third, the results suggest that uniform connectedness plays an important role in defining the entities available for attention selection. These results are discussed in terms of the manner in which attention selects objects in the visual environment.

Perceptual organization in schizophrenia: Utilization of the Gestalt principles.

In 2 experiments, the authors investigated perceptual organization in schizophrenia to determine whether patients with schizophrenia used the Gestalt principles. In the visual embedded figures task (Experiment 1), the authors examined the principles of proximity and collinearity, whereas in the similarity task (Experiment 2), the authors examined similarity. Forty-three people participated in the study: patients diagnosed with schizophrenia (14) or with bipolar disorder (15), and "normal" participants (14). All 3 groups of participants showed performance superiority in the condition that was facilitated by the use of the Gestalt principles in both tasks. This study supports the hypothesis that visual perceptual organization, in terms of utilizing the Gestalt principles, is relatively intact in people with schizophrenia.

Visual search strategy and perceptual organization covary with individual preference and structural complexity

The pattern of interactions between visual search profile (serial versus nonserial) and perceptual organization type (functionally local versus global) was investigated in three experiments. The task was a matching judgment performed on two separate figures that fit in a jigsaw-puzzle fashion. Reaction times and errors showed that serial search preferably goes together with local organization and nonserial search with global organization. Choice of search profile and organization type depend on task and individual preference. Structural complexity in the target area reinforces the combination of local organization and serial search. This combination was also chosen by subjects preferring accuracy. The combination of global organization and nonserial search was chosen with simpler targets or by subjects preferring speed. The results support an interactive notion of perceptual organization and search. Perceptual organization type is determined by individual preferences in combination with visual search task demands; visual search is guided by the specific organization of the stimulus pattern.

Perceptual organization in schizophrenia: utilization of the Gestalt principles.

In 2 experiments, the authors investigated perceptual organization in schizophrenia to determine whether patients with schizophrenia used the Gestalt principles. In the visual embedded figures task (Experiment 1), the authors examined the principles of proximity and collinearity, whereas in the similarity task (Experiment 2), the authors examined similarity. Forty-three people participated in the study: patients diagnosed with schizophrenia (14) or with bipolar disorder (15), and "normal" participants (14). All 3 groups of participants showed performance superiority in the condition that was facilitated by the use of the Gestalt principles in both tasks. This study supports the hypothesis that visual perceptual organization, in terms of utilizing the Gestalt principles, is relatively intact in people with schizophrenia.

Neonatal Cranial Ultrasound Abnormalities in Low Birth Weight Infants: Relation to Cognitive Outcomes at Six Years of Age

To assess the independent relation of neonatal cranial ultrasound (US) abnormalities in low birth weight (LBW) infants to cognitive outcomes at 6 years of age. Prospective cohort study. Six-year follow-up data were obtained on a regional birth cohort of LBW infants (< 2 kg) systematically screened as neonates with serial US. US abnormalities were dichotomized into isolated germinal matrix/intraventricular hemorrhage (GM/IVH) and parenchymal lesions/ventricular enlargement (PL/VE). Global cognitive outcomes (mental retardation, borderline intelligence, and normal intelligence) and selected specific cognitive abilities were assessed at 6 years of age with standardized instruments. Multivariate techniques were used to assess the effects of US independent of maternal social disadvantage at birth and other perinatal and neonatal risk factors. The sample as a whole had a significantly elevated rate of mental retardation (MR; 5%), almost all moderate to profound in severity. PL/VE was independently related to MR (odds ratio [OR], 65.8; confidence interval [CI], 19.1 to 22.4) and borderline intelligence (OR, 3.7; CI, 1.3 to 10.8); isolated GM/IVH was more modestly related to MR (OR, 4.6; CI, 1.2 to 18.6) but not related to borderline intelligence. Approximately half of the cases of MR were attributable to PL/VE independent of other factors. Of non-US factors, the number of days receiving mechanical ventilation increased the risk for MR. Maternal social disadvantage increased the risk for borderline intelligence but not MR. Among children of normal intelligence, those with PL/VE, but not isolated GM/IVH, performed more poorly than those without US abnormalities on tests of visual perceptual organization but not on tests of language, memory, or quantitative skills. Prevention of white matter injury would substantially improve cognitive outcomes for LBW infants.

Factor structure of psychoeducational and neuropsychological measures of learning-disabled children

This study investigated the factor structure of psychoeducational and neuropsychological measures used in the assessment of learning-disabled children. The Wechsler Intelligence Scale for Children-Revised, the Halstead-Reitan Neuropsychological Battery, the Peabody Picture Vocabulary Test, and the Wide Range Achievement Test were administered to 934 males and females between the ages of 8 and 16 years. A principal-components analysis with varimax rotation indicated the existence of seven factors: Verbal Reasoning, Academic Achievement, Visual-Perceptual Organization, Developmental, Visual-Motor Speed, Spatial Memory, and Attention and Concentration. Three factors provided new information about the functioning of learning-disabled children that may need to be considered before comprehensive identification and placement decisions can be offered. Results of this study lend support to the notion of utilizing neuropsychological measures as an adjunct to traditional psychoeducational assessment.

Visual perceptual organization in schizophrenic patients

Place & Gilmore (1980) proposed that schizophrenic patients are deficient in the perceptual organization of visual stimuli. According to their theory, the patients should be less influenced by global characteristics of visual displays. In the present experimental approach, 24 schizophrenics, 12 alcoholics and 24 healthy controls were asked to identify the number of lines presented for 23 ms on a video screen. In one condition, the stimuli were identical to those used by Place & Gilmore: up to six lines were shown at the corners of an imaginary hexagon; all lines were either in the same direction ('homogeneous') or differed in orientation ('heterogeneous'). In another condition the lines appeared at 10 different positions within the same field. The results of Place & Gilmore were not replicated; schizophrenics were only less influenced than the control group by different directions of the lines when three lines were presented. When more lines were presented, schizophrenics had the same advantage from homogeneity as the controls. If the basic configuration was a hexagon and six lines were presented, schizophrenics were able to profit very strongly from the global Gestalt. In summary, global characteristics of the visual displays do not facilitate visual information processing by schizophrenics as they do in the case of controls. However, if the basic Gestalt properties are strong enough, schizophrenics can take advantage of it. Thus the deficit of schizophrenics described by Place & Gilmore is relative and not absolute.

Subtypes of reading disability.

Subtypes of reading disability were studied through the application of cluster analysis. A battery of 23 measures of reading, language, auditory and visual processing, memory, perceptual organization, and visual-motor coordination was administered to 65 reading-disabled children. The primary clustering technique was the K-means iterative partitioning method which yielded three clusters that were subsequently found to be stable and reproducible. The clusters were characterized by the following: (1) a visual processing deficit; (2) a generalized language disorder; and (3) a minimal deficit subtype. These subgroups were consistent with findings from previous investigations of subtypes of reading disability. The quality of the clusters was assessed through a series of evaluation techniques developed specifically for this purpose and through a cluster analysis of randomly generated data drawn from a normal distribution with the same covariance matrix as the actual data. These analyses indicated that the clusters were relatively heterogeneous, and thus this typology may have limited clinical utility. It is possible that future investigations with more severely disabled readers may produce more homogeneous clusters.