April 13, 2012
Real Words vs. Non-Words, Baboons Know The Difference
Lawrence LeBlond for RedOrbit.com
The results of a new study reveal that baboons have the ability to discern real English words from fake words just by looking at them, suggesting that some mental processing involved in reading evolved separately from the specialized language centers that are unique to the human brain, scientists reported on Thursday.
The finding points to one of the key elements of human reading. Children learn the sounds of their ABCs before learning to read, but recognizing word shapes and lengths also plays a much stronger role in literacy, based on what researchers see in the baboon studies.
Reporting in the journal Science, the team trained six Guinea baboons to distinguish real, four-letter English words from non-words. After six weeks, the baboons learned to pick out dozens of words from a group of more than 7,800 non-words.
At the top of the class were Dan, who picked out 308 English words in the group, and Violette, who was able to distinguish 81 real English words from the list.
All of the monkeys in the study performed much better than 50 percent, averaging nearly 75 percent accuracy. Even seeing a word for the first time, the baboons, once trained, were more likely to recognize it as a real word, preferring them over the non-words.
Perhaps most remarkable, the French researchers also found that baboons mistook visually similar non-words for real words in exactly the same pattern that human readers do, said Charles Connor of the Mind-Brain Institute at John Hopkins University in Baltimore, Maryland, who was not involved in the study. “We´re seeing reading-like vision processes can occur in a species without language, and that is really surprising.”
Grainger noted that this study is not suggesting that the baboons are reading; “[they] don´t attach any meaning to the words other than recognizing shapes,” he said. “But the point is they can recognize the right ones, and ones close to the right ones.”
Cognitive psychologist Stanislas Dehaene of the College de France in Paris, said this study was “extraordinarily exciting.”
An expert on the neural basis of reading, Dehaene told Reuters reporter Sharon Begley that the researchers showed for the first time that “we have an animal model of a key component of literacy, the recognition of the visual word form.”
Grainger´s study was less intended as a study of animal intelligence than it was to explore how a brain might learn to read. It suggests that, contrary to popular theories, a brain can take the first steps toward reading without having language skills, especially since baboons don´t.
Results of the study suggest that “the basic biological mechanisms required for reading have deeper evolutionary roots than anyone thought,” said neuroscientist Michael Platt of Duke University, coauthor of an analysis on the study. “That suggests that reading draws on much older neurological mechanisms” and that apes or monkeys are the place to look for them.
Neuroscientists have long been puzzled by reading. Once humans first began doing it in the Middle East about 5,000 years ago, reading spread like wildfire across the ancient world, so fast in fact, that it could not have required genetic changes and entirely new brain circuitry. Those areas do not evolve that fast. Instead, its rapid spread suggests that reading co-opted existing neural structures.
“When we read, we´re capitalizing on object identification, an expertise we already have and one that´s quite ancient,” Grainger said. “We identify a table by its components: its tabletop and four legs. The same goes for identifying words using their component letters.”
The key difference between real words and non-words was the number of frequently recurring bigrams they contained. Bigrams are combinations of two letters, such as ℠it´ and ℠te´ in words such as ℠site´ and ℠kite´. The researchers minimized common bigrams in non-words and maximized them in real words, so that the baboons could discriminate on the basis of statistical dependence between letters.
The baboons revealed they were more likely able to spot words containing the most common bigrams. This correlation shows that they were truly learning and not just memorizing the words.
During the initial testing, baboons were given a reward of dry wheat for every correct response. Once they got the knack, the team decided to take it up a notch.
They showed the baboons strings of four letters that appeared on a screen, but these new strings were never-before-seen by the monkeys. If the baboons decided the letters formed a word, it pressed an oval sign; for non-words -- which always contained three consonants and a vowel -- it pressed a plus sign.
A short video of the tests, which can be viewed here, shows the baboons swatting the screen with enthusiasm and confidence, much like that of a child acing a video game.
Grainger said the baboons were engaging in “orthographic processing,” which means they are recognizing letters and their positions. While it has nothing to do with sounding out a word, or even understanding it, it is a necessary early step in reading.
Humans use similar cues when reading, said Emmanuel Keuleers, a psychologist at Ghent University in Belgium, who has conducted a similar experiment on humans. Despite their knowledge of English, “our participants partly relied on orthographic stimuli” to discern real words from non-words.
Grainger hopes the results seen in the baboon studies will aid in a clearer understanding of the neural abilities of skilled readers. The study may also help to uncover the causes of reading disabilities such as dyslexia, he added.
Grainger next plans to try to teach baboons an artificial alphabet, which could give greater control over the visual information that defines individual letters, and would provide a more precise idea of how baboons master word recognition.
Among the many surprises revealed in this study, the big one is that it involved baboons rather than their brainier relatives.
“Guinea baboons have a lot of social savvy, since they have to learn about complex male-male and male-female interactions in their troop,” primate curator Craig Demitros of the Brookfield Zoo outside Chicago, told Reuters. “They´re smart, but not at the level of chimps.”
This study, apart from providing a look into the evolution of the brain´s ability to read, also has implications for education. “You might conclude that phonics doesn´t work” as well as teaching children to read by recognizing the entire word, explained Pratt. “This study suggests that reading is all about pattern recognition and not working out phonemes.”