Although pigeons have brains that are no bigger than the tip of an index finger, several in a recent study were able to distinguish digitized microscope slides and mammograms of normal versus cancerous breast tissue.
Their rate of accuracy, about 90 percent in one experiment and 99 percent in another, is equivalent to that of humans with medical training. Don't expect pigeons at your next doctor's appointment, however.
The findings - published in the journal PLOS ONE - will be used to improve human performance at such tasks in future by correcting unclear aspects of the medical images, such as representations of tissue density. Evaluating tissue density has proven to be challenging not only for pigeons, but also for skilled human radiologists.
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"With some training and selective food reinforcement, pigeons do just as well as humans in categorizing digitized slides and mammograms of benign and malignant human breast tissue," lead author Richard Levenson, professor of pathology and laboratory medicine at UC Davis Health System, said in a press release.
"The pigeons were able to generalize what they had learned, so that when we showed them a completely new set of normal and cancerous digitized slides, they correctly identified them," he continued. "Their accuracy, like that of humans, was modestly affected by the presence or absence of color in the images, as well as by degrees of image compression."
"The pigeons," he added, "also learned to correctly identify cancer-relevant micro-calcifications on mammograms, but they had a tougher time classifying suspicious masses on mammograms - a task that is extremely difficult, even for skilled human observers."
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The training environment for the pigeons, shown in the below video, included a food pellet dispenser, a touch-sensitive screen that projected the medical image, as well as blue and yellow choice buttons on either side of the image. Pecks to those buttons and to the screen were automatically recorded.