Perceptual organization and its visual subcomponents in schizophrenia and schizotypy: A systematic review

Perceptual organization (PO) deficits have long been considered a hallmark of schizophrenia (SZ), reflecting disruptions in the integration of visual information. This systematic review critically evaluates the behavioral evidence for PO impairments in SZ and individuals with high schizotypal traits, focusing on three key mid-level processes: contour integration, perceptual grouping, and figure-ground segmentation. Forty-four studies were included, identified through a systematic search and evaluated for bias using the QUADAS-2 tool. Findings reveal robust and replicable deficits in contour integration among individuals with SZ, especially in those with disorganization symptoms, suggesting impaired lateral interactions in early visual areas. Perceptual grouping deficits were also prominent but appeared more sensitive to cognitive load and stimulus complexity, consistent with top-down integration failures. Figure-ground segmentation impairments were less consistently reported and often dependent on task demands, emerging more clearly under challenging conditions. In schizotypy, evidence of PO deficits was more variable. Some studies identified subtle impairments in contour integration and grouping, particularly under high attentional load or in individuals with disorganized traits, while others reported intact performance. The heterogeneity of methods across studies, particularly differences in stimulus type, complexity, and grouping cues, was a major limiting factor for cross-study comparisons. Findings from this review support a dimensional view of PO deficits, where specific symptom clusters, rather than diagnosis alone, predict perceptual dysfunction. PO impairments, particularly in contour integration, may serve as sensitive cognitive markers for early detection and targeted intervention in SZ-spectrum disorders.