Despite having brains no larger than the tip of a person’s index finger, pigeons can be trained to become pathologists capable of distinguishing between normal and cancerous breast tissues, new research published Wednesday in the journal PLOS One and reported by Futurity has revealed.

In the study, experts from the University of California, Davis and the University of Iowa taught pigeons to discriminate between cancerous and non-cancerous images and slides using a method called operant conditioning, in which they were given a food reward for choosing correctly.

“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, a professor of pathology and laboratory medicine at UC Davis, said in a statement.

Over time, the pigeons were able to generalize what they had learned, meaning that when they were exposed to a additional sets of normal and cancerous tissues on digitized slides, the birds were still able to correctly identify them.

Birds demonstrated 85 percent accuracy after just two weeks

The pigeons were subjected to a few weeks of training using stained pathology slides, including many benign and cancerous samples from routine cases at UC Davis Medical Center. Some of the first started by recognizing differences between the samples in full color at low magnification (4X) before moving on to medium (10X), and high (20X).

They were also tested using monochrome samples to eliminate color and brightness as possible cues, as well as with multiple levels of image compression. The birds even performed well on a series of images they had never seen before—effectively demonstrating that they were learned the difference between the two types of tissue and were able to learn limited pathology.

According to Levenson, the birds “were remarkably adept at discriminating between benign and malignant breast cancer slides at all magnifications, a task that can perplex inexperienced human observers… Pigeons’ accuracy from day one of training at low magnification increased from 50 percent correct to nearly 85 percent correct at days 13 to 15.”

Like humans, the pigeons’ accuracy rating was “modestly affected by the presence or absence of color in the images, as well as by degrees of image compression,” the UC Davis professor added. “The pigeons also learned to correctly identify cancer-relevant microcalcifications 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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Feature Image: Thinkstock

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