Radiologists face the visually challenging task of detecting suspicious features within the complex and noisy backgrounds characteristic of medical images. We used a search task to examine whether salience of target features in x-ray mammograms could be enhanced by prior adaptation to the spatial structure of the images. Observers were not radiologists and thus had no diagnostic training with the images. Stimuli were randomly selected sections from normal mammograms previously classified with BIRADS Density scores of “fatty” vs. “dense,” corresponding to differences in the relative quantities of fat vs. fibroglandular tissue. These categories reflect conspicuous differences in visual texture, with dense tissue being more likely to obscure lesion detection. Targets were simulated masses corresponding to bright Gaussian spots (sd = .18 deg), superimposed by adding the luminance to the background. A single target was added to each image at random locations, with contrast varied over 5 levels so that they varied from difficult to easy to detect. Reaction times were measured for detecting the target location (left or right side), before or after adapting to a gray field or random sequences of a different set of dense or fatty images. Observers were faster at detecting the targets in either dense or fatty images after adapting to the specific background type (dense or fatty) they were searching within. Thus the adaptation led to a facilitation of search performance that was selective for the background texture. Our results are consistent with the hypothesis that adaptation allows observers to more effectively suppress the specific structure of the background, thereby heightening visual salience and search efficiency.
We examined how visual sensitivity and perception are affected by adaptation to the characteristic amplitude spectra of X-ray mammography images. Because of the transmissive nature of X-ray photons, these images have relatively more low-frequency variability than natural images, a difference that is captured by a steeper slope of the amplitude spectrum (~ − 1.5) compared to the ~ 1/f (slope of − 1) spectra common to natural scenes. Radiologists inspecting these images are therefore exposed to a different balance of spectral components, and we measured how this exposure might alter spatial vision. Observers (who were not radiologists) were adapted to images of normal mammograms or the same images sharpened by filtering the amplitude spectra to shallower slopes. Prior adaptation to the original mammograms significantly biased judgments of image focus relative to the sharpened images, demonstrating that the images are sufficient to induce substantial after-effects. The adaptation also induced strong losses in threshold contrast sensitivity that were selective for lower spatial frequencies, though these losses were very similar to the threshold changes induced by the sharpened images. Visual search for targets (Gaussian blobs) added to the images was also not differentially affected by adaptation to the original or sharper images. These results complement our previous studies examining how observers adapt to the textural properties or phase spectra of mammograms. Like the phase spectrum, adaptation to the amplitude spectrum of mammograms alters spatial sensitivity and visual judgments about the images. However, unlike the phase spectrum, adaptation to the amplitude spectra did not confer a selective performance advantage relative to more natural spectra.Electronic supplementary materialThe online version of this article (10.1186/s41235-018-0089-4) contains supplementary material, which is available to authorized users.
This study found that women with serious mental illness (SMI) face a number of challenges with regard to the motherhood identity. They may opt out of, face derailed plans for, or reimagine different ways of embodying the motherhood role. Clinicians can support women with SMI in their decision-making process with regard to having children or not, as well as to access needed resources.
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