Key points are not available for this paper at this time.
Experiments are reported which serve to elucidate how the detection of abnormalities is influenced by the surround in which they are embedded. A measurable quantity, the conspicuity was formulated, defined as the ratio of feature contrast to surround complexity. The latter was expressed as the rate of change of surround density variation. Observer tests, involving the task of A) detecting a solitary nodule on chest radiographs, and B) the visualization of the gall bladder on cholecystograms, indicate that the measured conspicuity value correlates well with the probability of detecting a feature.
Révész et al. (Fri,) studied this question.