Mammography screening is recommended for a large population of women, aiming at detecting the initial signs of breast cancer. However, due to the complexity of the breast parenchyma and to the low prevalence of cancer in the screening population, among other factors, a significant fraction of cancers are not initially reported, being only found in retrospect. Fault visual search, that is, not examining the area where the cancer is located, is responsible for a third of these misses, but all other unreported cancers attract some amount of visual attention, as indicated by the duration of visual gaze in the location of the lesion. Thus, perceptual and decision making mechanisms must be understood, in order to aid radiologists in detection cancer at earlier stages. We have been working on modeling these mechanisms by using spatial frequency analysis, in a process that is inspired by the one performed by the eye-brain system. In this paper we compare the spatial frequency representation of areas that contain reported cancers and that of the same area on the previous mammogram, where the cancer was either not reported or it was reported as a benign lesion. In addition, we contrast the representation of these areas containing cancerous lesions with the representation of the corresponding area in the cancer-free contra-lateral breast.