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Monday June 26 2017

Trust me, I’m a doctor

What comes to mind when you think about pigeons? Flying rats? Waddling fowls? How about medical professionals? As outlandish as this notion appears, it isn’t nearly as far-fetched as one might think. A recent study from the University of Iowa and the University of California demonstrate the remarkable ability of pigeons to distinguish between cancerous and benign pathology and radiology slides.[1] The pigeon species is no stranger to these types of studies. Famously, they were the subjects of behavioural psychologist B.F. Skinner’s operant conditioning tests.[2] Pigeons were placed inside a puzzle box, endearingly referred to as the Skinner box, and trained to do a simple task such as pressing a button. Every time the pigeon successfully completes this task, it would be rewarded with a food pellet. Through this method, the pigeons could be trained to do increasingly difficult tasks.[3]

The basis of operant conditioning is employed in this recent study, where a cohort of eight pigeons were trained to distinguish pathological histology slides: four were trained to distinguish calcification in mammograms, and four were trained to distinguish masses in mammograms. The pigeons underwent an initial training phase to detect images of varying magnifications. After as little as two weeks, a pigeon’s accuracy in determining cancerous from benign histology slides at low magnification increased from 50% to 85%. Subsequently, they were presented with a new set of images to classify, and performed at a similar accuracy. Even more amazingly, when the pigeons were gathered into groups of four to formulate an answer together, referred to as “flock-sourcing”, their accuracy reached an astonishing 99%.[2]

Unfortunately, these clever birds were unable to perform the more challenging task of identifying the malignant potential masses in mammograms. This task is challenging even in humans, with only an 80% reported accuracy. The pigeons took several weeks during the training phase to learn to classify the masses at a similar accuracy, but when shown novel sets of images, performed at a level no better than chance. This suggests that the pigeons resorted to rote memorization rather than demonstrating learning as they did with histology images.[2]

References

  1. ScienceDaily,. ‘One Very Brainy Bird: Study Finds Pigeons Uncommonly Good At Distinguishing Cancerous From Normal Breast Tissue’. N.p., 2015. Web. 19 Nov. 2015.
  2. Levenson, Richard M. et al. ‘Pigeons (Columba Livia) As Trainable Observers Of Pathology And Radiology Breast Cancer Images’. PLOS ONE 10.11 (2015): e0141357. Web.
  3. Funder, David Charles. The Personality Puzzle. New York: W.W. Norton, 1997. Print.

Image courtesy of Julianne Westrich at http://paperbackpigeon.com

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