A Disorder of Simultaneous Form Perception

SOME patients with cerebral cortical disease find it peculiarly difficult to interpret complex pictures. Though they are able to point out individual details, the event or situation portrayed escapes them. Potzl (1928) was content to accept this as a specific and isolated visual agnosia for pic-torially represented situation and events. But others have sought for a more general explanation. The disorder has been regarded either as a non-specific manifestation of mental deterioration or as a specific disorder of visual perception, affecting the ability to interrelate simultaneously perceived visual data in a meaningful way. There is always the question as to whether failure to understand indicates an agnostic disorder in the usual sense or a more general intellectual deficit (Weisenburg and McBride, 1935). Both views assume that these patients are as well able as normal subjects to perceive the various details of a picture simultaneously, or nearly so. The possibility that although individual form perception is preserved, simultaneous form perception is defective, has never been systematically examined. Heilbronner (1905) described a patient who failed in picture inter-pretation though able to list details, and misread words though able to name the constituent letters. To him this implied the inability to appre-hend the details as constituting a whole. Wolpert (1924) described in detail a patient who was unable to interpret pictures from the Binet-Bobertag series and who could only read by spelling out the individual letters of the words slowly and laboriously: any attempt to read more quickly resulted in numerous misreadings. To explain his patients difficulties, Wolpert elaborated the idea of a gnostic disorder, a disorder of the final step in perception, the highest gnostic function, namely the apprehension of the whole (Gesamtauffassung). This disorder, which he regarded as revealed by tests of picture inter-pretation and reading but by no means limited to these activities, he named by guest on M