Visual lobe area mapping for targets on a competing homogeneous background

Binocular visual lobe areas for two subjects were mapped over part of the visual field. Overall, the lobe shapes were strikingly consistent over a period of 18 months with regard to boundary irregularities and regions of insensitivity. The ratio of eight-axis mapping area to eight-axis area based on complete mapping data was near unity for one subject but very much higher for the other. If these results are typical, the various methods of determining lobe area from measurements taken on a few axes can only give very approximate relative values. It was suggested that the irregular boundary and areas of insensitivity may partly account for the difficulty some subjects experience in locating targets during visual search, even after repeated scanning.