A half-second glimpse often lets radiologists identify breast cancer cases even when viewing the mammogram of the opposite breast

Humans are very adept at extracting the “gist” of a scene in a fraction of a second. We have found that radiologists can discriminate normal from abnormal mammograms at above-chance levels after a half-second viewing (d′ ∼ 1) but are at chance in localizing the abnormality. This pattern of results suggests that they are detecting a global signal of abnormality. What are the stimulus properties that might support this ability? We investigated the nature of the gist signal in four experiments by asking radiologists to make detection and localization responses about briefly presented mammograms in which the spatial frequency, symmetry, and/or size of the images was manipulated. We show that the signal is stronger in the higher spatial frequencies. Performance does not depend on detection of breaks in the normal symmetry of left and right breasts. Moreover, above-chance classification is possible using images from the normal breast of a patient with overt signs of cancer only in the other breast. Some signal is present in the portions of the parenchyma (breast tissue) that do not contain a lesion or that are in the contralateral breast. This signal does not appear to be a simple assessment of breast density but rather the detection of the abnormal gist may be based on a widely distributed image statistic, learned by experts. The finding that a global signal, related to disease, can be detected in parenchyma that does not contain a lesion has implications for improving breast cancer detection

HENRY WILLIAM RAVENEL, 1814-1887: SOUTH CAROLINA SCIENTIST IN THE CIVIL WAR ERA

Recent historical interest in science in the Old South inspired this biography of mycologist Henry Ravenel (1814-1887). Prior writing on antebellum southern science was done without the benefit of strong monographs on southern scientists or institutions. Writing done in such a vacuum was necessarily very general and distorted in its perspectives. T. Carey Johnson exaggerated the importance of southern science, while Clement Eaton denigrated it, attributing the South's supposed lack in scientific contributions to the effect of two of her major institutions: slavery and religious orthodoxy. Henry Ravenel, though a South Carolina slaveholder and a devout Episcopalian, was also one of a small group of leaders in antebellum American botany. He was a familiar correspondent to such other top American botanists as Asa Gray, Edward Tuckerman, William Sullivant, Moses Ashley Curtis and Alvan Wentworth Chapman. He also corresponded with a number of European scientists, particularly Miles Joseph Berkeley. To Berkeley he sent specimens of fungi together with detailed notes and descriptions. Berkeley would examine his collections and name new species, sometimes sharing authorship with Ravenel. Between 1852 and 1860 Ravenel published a five volume fungus exsiccati, or collection of dried plants. During this early period of his career, Ravenel's residence in the South, ownership of slaves and religious piety presented no impediment to his pursuit of botany. Civil War nearly bankrupted the once-wealthy man. Ravenel returned to botany after the Civil War to earn money by selling collections. He no longer had time to study the theoretical foundations of taxonomy nor the money to purchase botanical books. In addition, for the first time Ravenel suffered some discrimination from northern botanists. The postbellum period, then, is revealed as the time when residence in the South first became a liability to Ravenel's pursuit of botany