Monkeys banging on typewriters might never reproduce the works of Shakespeare, but they may be closer to reading Hamlet than we thought. Scientists have trained baboons to distinguish English words from similar-looking nonsense words by recognizing common arrangements of letters. The findings indicate that visual word recognition, the most basic step of reading, can be learned without any knowledge of spoken language.
The study builds on the idea that when humans read, our brains first have to recognize individual letters, as well as their order. "We're actually reading words much like we identify any kind of visual object, like we identify chairs and tables," says study author Jonathan Grainger, a cognitive psychologist at France's National Center for Scientific Research, and Aix-Marseille University in Marseille, France. Our brains construct words from an assembly of letters like they recognize tables as a surface connected to four legs, Grainger says.
Much of the current reading research has stressed that readers first need to have familiarity with spoken language, so they can connect sounds (or hand signs for the hearing-impaired) with the letters they see. Grainger and his colleagues wanted to test whether it's possible to learn the letter patterns of words without any idea of what they mean or how they sound—that is, whether a monkey could do it.
The scientists used a unique testing facility, consisting of a trailer with computers set up next to a baboon enclosure, which the animals could enter at will and perform trials on the touch-screen computers for as long as they pleased. The computers cued up the appropriate test for each of the six study baboons using microchips in their arms. When letters appeared on the monitor, the baboons got wheat rewards for touching the correct shape on the screen: an oval on the right of the screen if the word was real, and a cross on the left if it was nonsense (see video).
The researchers showed the baboons English words consisting of four capital letters, such as "DONE" or "LAND." They also showed "nonwords" that looked similar to words, such as "DRAN" or "LONS." A key distinction between words and nonwords was that nonwords contained pairs of letters that occur together less frequently in English. For example, "HT" is less common than "TH." Baboons saw the real words many times as the trials progressed, but the nonwords were rarely repeated. Each animal completed between 40,000 and 60,000 trials over the course of a month and a half.
Surprisingly, the baboons learned to distinguish scores of real words—the star pupil learned 308, but even the worst mastered 81—from 500 words and 7832 nonwords with about 75% accuracy, the researchers will report in tomorrow's issue of Science. Of course, the baboons were not actually reading, because they didn't know what the words meant. But the findings show that they broke the words into their component parts instead of just memorizing the shapes of whole words, says Grainger. Just like humans, baboons were more likely to mistake a nonword for a word if it contained letter pairings that were common in real words.
"They're using information about letters and the relations between letters," Grainger says. "This suggests this has to be linked to some kind of ancient ability that's not linguistic at all, but just related to a fundamental ability to recognize objects." He says the fact that some baboons found the task harder than others could be a "window into visual factors contributing to dyslexia."
Although there's no doubt that spoken language is extremely important for humans who are learning to read, the performance of nonspeaking baboons highlights the importance of the visual aspects of reading, says Anne Castles, a reading researcher at Macquarie University in Sydney, Australia. "Children ultimately do have to recognize a string of letters on the page," she says. "It's important for us to learn how they do that, and what factors influence how well they do."
So, can we expect literate baboons in the near future? "One of the projects we're particularly interested in trying out very soon is getting baboons to associate words with some kind of meaning," Grainger says. "This is definitely going to be the next step." Shakespeare can rest easy, however. Grainger says, "It's going to be extremely complex."