Threshold Contrast as a Function of Target Complexity

Contrast‐luminance relationships were obtained for B test targets, presented for 0.2 second in the center of an extensive uniform field, and having various degrees of complexity. They always were brighter than the background. The luminance of which could be set at predetermined values from 1 to 500 footlamberts. The contrast‐luminance relationships were a function of the target characteristics. difference coming more marked for background luminances greater than about 10 footlamberts. A comparison with the results obtained by previous investigators with three of the targets indicates that the functional relationships are not significantly affected by experimental procedures or observers Target complexity appears to be only one of several factors which influence the form of the contrast luminance relationships. Considerable difference in the absolute values of threshold contrast were found for targets having approximately the same size of critical detail.