VISUAL SEARCH PATTERNS OF RADIOLOGISTS IN TRAINING.

At the present time, the information contained in a roentgenogram can be extracted only by a radiologist observing it. That this link can sometimes fail has recently been emphasized by Tuddenham (1) and Garland (2), who have reported frequent perceptual errors by radiologists viewing roentgenograms demonstrating fairly obvious lesions. Such errors have also been shown by Zeidner and Sadacca (3) and Enoch (4) in their studies of photointerpreters reading aerial photographs. There are two stages in the visual perception of detail. First, the object must be focused upon the fovea; second, this focused image must be translated into meaning by the observer's brain. The fovea subtends an angle of only 2°, so that at 30 inches the area of distinct vision is a circle about 1 inch in diameter. Thus, some 300 separate eye fixations are necessary to cover the area presented by a 14 × 17-inch roentgenogram at this distance. The eye searches the film by moving in small rapid jumps of high velocity (saccadic movements)...