‘Wasp’ is an English word, but ‘telk’ is not. You and I know this because we speak English. But in a French laboratory, six baboons have also learned to tell the difference between genuine English words, and nonsense ones. They can sort their wasps from their telks, even though they have no idea that the former means a stinging insect and the latter means nothing. They don’t understand the language, but can ‘read’ nonetheless.
At its most basic level, reading is about recognising patterns. We look at letters (or other symbols) and identify them based on their number, position and angles of lines. This is a trivial task, and one that doesn’t require any language. Letters are no different to any other object in our environment that we can recognise. A pigeon can be trained to do discriminate between letters.
The next step is harder. We unite letters into words by looking at their positions relative to one another. This is called “orthographic processing”. It’s the stage where, according to general consensus, language kicks in. As we see clusters of letters, we think about the sounds they represent and we read the word aloud in our heads. But Jonathan Grainger from Aix-Marseille University has shown that orthographic processing can happen without any knowledge of language, or how words are meant to sound.
Grainger trained baboons to recognise English words, and tell them apart from very similar nonsense words. The monkeys learned quickly, and could even categorise words they had never seen before. They weren’t anglophiles by any stretch. Instead, their abilities suggest that the act of reading words is just a more advanced version of the pattern-recognition skill that lets us identify letters. It’s a skill that was there long before the first human had scrawled the first letter.
The baboons lived in a unique facility designed by Joel Fagot, where they can volunteer for experiments. Their enclosures included touch-screens that would flash a real four-letter English word, like ‘done’, ‘land’ or ‘vast’, or non-words, like ‘dran’, ‘lons’ or ‘virt’. The baboon had to categorise the words and non-words by touching one of two shapes. If they got the right answer, they earned a tasty reward. Unlike many similar experiments, the animals decided when they wanted to take part.
None of the six baboons had seen words or letters before. But over a month and a half, and thousands of trials, all of them learned to distinguish words from non-words with around 75 per cent accuracy (50 per cent would be pure guesswork). The most successful of them – Dan – built up a vocabulary of 308 words.
Their achievement is remarkable, not least because the non-words were very similar to the actual ones. Rather than obvious fakes like ‘qzxc’, they all contained pairs of letters that occur in real words, although they veered towards rarer combinations. And the monkeys weren’t just memorising the words. They were still more likely to pick a set of letters they had never seen before, if it was an actual English word.
Grainger thinks that the baboons learned to tell the real words from the fakes by using the frequencies of letter combinations within them. They learned which combinations were most likely to be found in real words, and made their choices accordingly. They had gleaned the stats of English, without any knowledge of the language itself.
Stanislas Deheane, one of the leading figures in the science of reading, thinks that the study is “extraordinarily exciting”. He says, “It fits very nicely with my own research, which suggests that reading relies, in part, on learning the purely visual statistics of letters and their combinations.”
But Noah Gray, a neuroscience editor at Nature, says that “Dan” may have skewed the results by performing exceptionally well. “The “animal genius” effect is big,” he said on Twitter. “Remove ‘Dan’ & effect isn’t nearly as impressive.”
, Grainger’s study also suggests that the primate brain was already pre-adapted to process printed words. When we invented writing systems, we co-opted ancient neural circuits that help primates to recognise patterns. This shouldn’t be surprising. Written language is only around 5,000 years old, and millions of people today still cannot read. We can, however, develop that ability very quickly. In the 19th century, when the Cherokee of North America finally invented a writing system for their spoken language, they started learning and using it within a single generation.
Deheane has shown that one part of the brain, of the many that activate when we read, selectively buzzes in response to written characters, rather than other sights or spoken words. This region is known as the left visual word form area (VWFA), and Deheane now wants to see if Grainger’s baboons activate the equivalent area when they discriminate between real and fake English words.
By recording the activity of individual neurons in the brains of baboons, while they look at words, Deheane thinks it will be possible to “examine the neural code for written words”. He suspects that we will find “bigram neurons”, which are tuned to a specific combination of two letters, such as ‘EN’. “I can’t wait to see if this prediction holds up,” he says.
Reference: Grainger, Dufau, Montant, Ziegler & Fagot. 2012. Orthographic Processing in Baboons (Papio papio). Science http://dx.doi.org/10.1126/science.1218152
Updated: to include Noah Gray comments
Photo by Joel Fagot; images from Science/AAAS