Abstract
Contour Integration (CI) is the ability to integrate elemental features into objects and is a basic visual process required to recognize target objects in a visually noisy environment. The ability to accurately identify contour shapes follows Gestalt grouping principles such as similarity, proximity, and common fate, to achieve representations such as curvature and closure. Previous research has shown that CI is impaired in individuals with schizophrenia. Here, we characterize performance on a series of contour shapes, made up of Gabor elements, that varied in extent of both closure and curvature in schizophrenia patients (SP) and neurotypical (NT) individuals. Twenty-four SP and fifteen NT participants conducted up to 40 sessions on a CI task involving 15 unique shapes, classified into 7 families of Lines, Ellipses, Circles, Spirals, Blobs, Squiggles, and Letters. In each session, different tasks were used to estimate thresholds for Orientation Jitter (OJ; i.e. orientation deviations of individual Gabor elements from ideal for each shape), or Inducer Number (IN; i.e. number of Gabor elements defining the shape). Results show OJ and IN thresholds significantly differed between the SP and NT groups, with better thresholds observed in the NT group. Furthermore, we found significant differences as a function of the Contour type. In agreement with previous findings, participants in both groups performed relatively better on shapes with low curvatures (e.g., Lines) in comparison with high curvatures (e.g., Blobs). We discuss how CI can be used to discriminate perceptual organization deficits in individuals with schizophrenia, as well as how some contour shapes may be more discriminative than others in revealing perceptual organization deficits in this population.