Mind what you read in the park, because pigeons could be reading it too.
Well, kind of. Scientists have taught pigeons a bit about the English language, according to a study published Monday in the Proceedings of the National Academy of Sciences. Although the birds don’t understand the meanings of any words (yet!), they were able to distinguish real words from non-words by visually processing the letter combinations involved.
“The ability to recognise words is one of the building blocks on which reading is built and, it appears we share that ability with pigeons,” Damian Scarf, a lecturer at New Zealand’s University of Otago and a co-author of the study, told The Huffington Post in an email.
The pigeons in the study were trained to identify four-letter English words on a display by pecking at them. When the screen showed a four-letter combination that only resembled a word ― such as “URSP,” for example ― the pigeons pecked a symbol instead.
In the video below, you can see a pigeon learning to differentiate between words and non-words. It takes a couple tries, but eventually the pigeon catches on that while GREY, BUST and HOST are all words, SUKS and GRRU are not.
The pigeon research supports a particular theory about how humans evolved the ability to learn to read. We have a brain region called the visual word form area, which allows us to visually recognize words by coding their orthographic properties ― that is, the letter combinations that are special to words.
Letters and words, of course, are human inventions. They never existed in our natural environment before we conceived of them. Yet we have the neuronal machinery that can learn to recognize them. Some scientists have suggested that this is due to a phenomenon they call neuronal recycling, in which neural circuits for vision that evolved to recognize objects are repurposed to process words.
Studying pigeons and other birds can help scientists go back in time and get a glimpse into earlier stages of evolution. “Unfortunately, unlike bones, brains do not fossilise,” Scarf said. “Working with non-human animals gives us a window into the abilities our ancestors may have possessed, effectively the building blocks of our modern day intelligence.”
Pigeons are separated from humans by 300 million years of evolution, and their brain architecture is categorically different from that of humans and other primates.
Yet as the study shows, their visual system can learn how to process the orthographic conventions of the English language. This suggests that neuronal recycling, or the flexibility of the visual system to code things it did not evolve to code, is a property that may be common to all vertebrate visual systems, Scarf said. It may have been present even in the last common ancestor we shared with pigeons, 300,000,000 years ago.
The pigeons in the study still have a very limited vocabulary― they learned to tell fewer than 60 words from some 8000 non-words. But this rudimentary reading skill wasn’t simply due to memorizing the visual patterns of those words, the researchers said. Instead, the birds appeared to learn some of the rules that govern the properties of words, such as the common occurrence of certain letter pairs.
“We presented them with words they had never seen before,” Scarf said. “They performed above chance on these novel words, suggesting they were not simply memorizing the words they learnt and were sensitive to certain properties of words.”
Most people don’t think of pigeons as particularly smart animals. But researchers know differently. To people who study pigeons, the term “bird brain” carries a totally different meaning.
“I have been working with pigeons for a decade, and [my colleague Michael Colombo] much longer than that, and I do not think either of us are surprised anymore,” Scarf said.
The news of literate pigeons is only the latest in a series of findings that could change how we think about “human versus animal intelligence.” Pigeons, crows and some fish can recognize and remember human faces. Crows have been found to use tools, a skill traditionally thought to be just for humans (and some other big-brained primates). Chimps can beat humans by far in working memory tests, and dogs have a rather sophisticated understanding of our language.
And Scarf believes pigeons may actually be the winner in this intelligence contest.
“Maybe on the surface they do not seem intelligent, they do not use tools like many corvids or talk like many parrots,” he said. “But these abilities are likely innate.”
Scarf suggested that “true intelligence, and perhaps what makes humans so intelligent, is the ability to do things that are completely outside of your wheelhouse.”
“On this measure I think pigeons have demonstrated the highest level of intelligence among birds,” he said. “For decades they have demonstrated their ability to perform tasks that in many cases were thought unique to humans. I think corvids and parrots have some catching up to do.”