Processing of local and global visual features in obsessive-compulsive disorder.

Research conducted with the Rey-figure task has suggested that patients with obsessive-compulsive disorder (OCD) process local aspects of a complex stimulus more efficiently than the overall gestalt. The aim of the present study was to investigate if this "local bias" is established already during early stimulus encoding or occurs only during later processing, once a percept has been formed (e.g., memory retrieval). To this end, responding to local and global targets of hierarchical letters (e.g., an "E" composed out of small "T"s) was assessed in 30 OCD patients and 28 healthy controls. OCD patients and controls performed comparably on all parameters. These results lend no support to the notion of an early perceptual bias towards local elements in OCD patients. It remains to be tested whether a bias towards local features is confined to situations where local and global features compete for selection.