Studies at the two universities produced intriguing insights into the ability of pigeons to discriminate between benign and malignant breast cancer slides at all magnifications

Researchers at the University of Iowa and the University of California Davis (UC Davis) are reporting intriguing results from a study indicating that pigeons have the potential to be “proficient pathologists” when it comes to telling the difference between healthy and cancerous cells in human breast tissue.

With minimal training and food reinforcement, the common pigeon or rock dove, performed as well as humans at identifying and classifying (AKA, pigeonholing) digitized slides and mammograms of benign and malignant human breast tissue, stated the researchers.

Pigeons Found to be Highly Observant

In the experiment, eight pigeons were placed into separate boxes while images of cancer cells from slides were projected onto a screen. The birds were trained to peck on one colored square on a computer screen if the image of the cells appeared malignant and another colored square if the image of the cells appeared benign. When the bird was correct, it received a treat. The researchers outlined their study in a report published on the Public Library of Science (PLOS/one) website titled, “Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images.”

To abrogate the possibility that the birds were not simply memorizing the correct responses, new samples were presented. The pigeons were then given treats, regardless of whether a correct answer was given or not. The pigeons performed approximately the same when presented with the new images, leading the researchers to indicate that they could be beneficial as trained medical image observers.

“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, who typically require considerable training to attain mastery,” said Richard Levenson, MD (above), Professor and Vice Chair for Strategic Technologies in the Department of Pathology and Laboratory Medicine at UC Davis. (Photo copyright: UC Davis.)

“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, who typically require considerable training to attain mastery,” said Richard Levenson, MD (above), Professor and Vice Chair for Strategic Technologies in the Department of Pathology and Laboratory Medicine at UC Davis. (Photo copyright: UC Davis.)

Pigeons Incredibly Discriminating in Their Decision-making

Some birds were able to recognize benign or malignant samples in full color at low magnification and were later able to competently progress to medium and high magnifications. Monochrome samples were also used in the research to eradicate the possibility that color and brightness were prompting the choices the pigeons selected.

“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, who typically require considerable training to attain mastery,” said Richard Levenson, MD, Professor and Vice Chair for Strategic Technologies in the Department of Pathology and Laboratory Medicine at UC Davis. “[The] pigeons’ accuracy from day one of training at low magnification increased from 50% correct to nearly 85% correct at days 13-15,” Levenson told NBC News.

The pigeons’ training environment. The operant conditioning chamber was equipped with a food pellet dispenser, and a touch-sensitive screen upon which anatomic pathology and radiology images (center) and choice buttons (blue and yellow rectangles) were presented. (Image and caption copyright: PLOS/one.)

The pigeons’ training environment. The operant conditioning chamber was equipped with a food pellet dispenser, and a touch-sensitive screen upon which anatomic pathology and radiology images (center) and choice buttons (blue and yellow rectangles) were presented. (Image and caption copyright: PLOS/one.)

Pigeons Perform Even Better in Groups

The pigeons performed even better when the researchers put together the combined efforts of four pigeons. When the assemblage of birds was shown a set of uncompressed images, the accuracy level of this “flock source” was an amazing 99%! This exceeded the skill level achieved by any of the four individual birds.

“The results go a long way toward establishing a profound link between humans and our animal kin,” stated Edward Wasserman, PhD, and Professor of Psychological and Brain Sciences at the University of Iowa, and co-author of the study, in a Science Blog article. “Even distant relatives, like people and pigeons, are adept at perceiving and categorizing the complex visual patterns that are presented in pathology and radiology images, surely a task for which nature has not specifically prepared us.”

The birds were also able to identify microcalcifications on mammograms. However, they had difficulty evaluating the malignant potential of breast masses without microcalcifications, a task that is also challenging for humans. It took the pigeons several weeks to learn to classify the breast masses in the mammogram training set, which was considerably longer than the few days it took them to master the histopathology tests. Furthermore, when the birds were shown previously unseen images, they failed to perform at a level better than chance.

“The data suggests that the birds were just memorizing the masses in the training set, and never learned how to key in on stellate margins and other features of the lesions that can correlate with malignancy,” Levenson told Science Blog. “But, as this task reflects the difficulty even humans have, it indicates how pigeons may be faithful mimics of the strengths and weaknesses of humans in viewing medical images.”

“These results go a long way toward establishing a profound link between humans and our animal kin,” said Edward Wasserman, PhD, and Professor of Psychological and Brain Sciences at the University of Iowa. Shown above with one of the pigeons used in the study. (Photo copyright: University of Iowa.)

“These results go a long way toward establishing a profound link between humans and our animal kin,” said Edward Wasserman, PhD, and Professor of Psychological and Brain Sciences at the University of Iowa. Shown above with one of the pigeons used in the study. (Photo copyright: University of Iowa.)

Pigeons Much More Intelligent than Generally Believed

We typically view pigeons as undesirable and unwanted pests, clogging our city parks with their seemingly nonstop coos and excrement. However, pigeons—despite having a brain about the size of a walnut—have been proven to be one of the most intelligent of all bird species. It is the only non-mammal, and one of only six species, that has the ability to recognize its own reflection in a mirror. And pigeons have a long history interacting with humans.

Archaeology has discovered that pigeons have lived alongside man for thousands of years, dating back to Mesopotamia 3,000 BC. They have, at times, been helpful creatures with their ability to serve as messengers. Pigeons have been used during wartime to carry information across enemy lines and reveal the location of a sinking ship, saving hundreds of human lives in the process.

Research Illustrates How Humans Process Visual Information

The successes and difficulties the pigeons encountered during the research provide a perspective into how humans process visual cues present on slides to diagnose diseases.

The collaboration between the two universities began when Levenson learned about Wasserman’s earlier research on the visual short-term memory capacity of pigeons and wondered how the birds would perform while scrutinizing pathology slides.

“Research over the past 50 years has shown that pigeons can distinguish identities and emotional expressions on human faces, letters of the alphabet, misshapen pharmaceutical capsules and even paintings by Monet versus Picasso,” said Wasserman in the Science Blog article. Wasserman has conducted studies on pigeons for several decades.

Pigeons also have outstanding visual memory and are able to recall more than 1,800 images. Researchers have not yet discovered how or why pigeons are so effective at differentiating between intricate and diverse visual stimuli, but it appears that color, shape, size, texture and patterns all contribute to their success.

Despite the fact that, if used to diagnose histopathology images, pigeons would work for “chicken feed,” there is little likelihood that pigeons will replace humans as pathologists anytime soon. Rather, the findings of this research project indicate that further study of pigeons and how they process images could add insight into how humans view and process images. Such additional studies could add useful insights that would inform efforts to improve the accuracy of digital pathology systems.

—JP Schlingman

Related Information:

Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images

Bird Brain? Pigeons Make Good Pathologists, Study Finds

Brainy Bird: Pigeons Uncommonly Good at Distinguishing Cancerous From Normal Breast Tissue

Pigeons Spot Cancer as Well as Human Experts

Researchers Train Pigeon Pathologists to Read Mammograms

Pigeons to Replace Pathologists in Diagnosing Benign from Malignant Tumors