There is a common saying that being a bird brain means you are not very bright. But how bright is that? Pigeons can learn abstract numerical rules, a skill that scientists had believed only primates possessed. Although the birds may not be able to do higher math, their ability to reason numerically is likely something that a wide variety of species can do, too, researchers say. Many species, from honeybees to elephants, can discriminate between quantities of items, sounds, or smells, and represent numbers mentally. However only primates (all species, from lemurs to chimpanzees) were known previously to be able to reason numerically.
There is a common saying that being a bird brain means you are not very bright. But how bright is that? Pigeons can learn abstract numerical rules, a skill that scientists had believed only primates possessed. Although the birds may not be able to do higher math, their ability to reason numerically is likely something that a wide variety of species can do, too, researchers say. Many species, from honeybees to elephants, can discriminate between quantities of items, sounds, or smells, and represent numbers mentally. However only primates (all species, from lemurs to chimpanzees) were known previously to be able to reason numerically.
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University of Otago researchers showed that pigeons can compare pairs of images picturing up to nine objects and order them by the lower to higher number with a success rate above chance.
"Our research not only shows that pigeons are also members of this exclusive club, but, somewhat surprisingly, their performance is on a par with that of monkeys." says lead author Damian Scarf.
The researchers initially trained the pigeons by presenting them with 35 sets of three images, each with one, two, or three objects of different sizes, colors and shapes.
They were rewarded with wheat when they pecked the images in the correct ascending sequence.
Next, the researchers sought to test if the pigeons could take what they had learned from ordering the three images and apply it to images with higher numbers of objects than they had seen before. The pigeons were presented with pairs of images with between one and nine objects and tested on their ability to respond to them in ascending order.
As well as performing above chance in these tests, the pigeons also demonstrated a distance effect comparable to that found in landmark US research in 1998 involving rhesus monkeys performing similar tasks. The greater the distance between the numbers in the pairs, the faster and more accurate the pigeons were, Dr Scarf says.
"While this is obviously a long way away from how humans can count, it shows that an animal with a brain structured quite differently to ours is still able to perform complex mental tasks of which only humans were once thought capable. Our findings add to a growing body of evidence that pigeons are among a number of avian species exhibiting impressive mental abilities that really do give the lie to the old bird brain insult," he says.
Pigeons have been previously found to have the capacity to share attention between different dimensions of a stimulus, but (like humans and other animals) their performance with multiple dimensions is worse than with a single stimulus dimension.
Pigeons can be taught relatively complex actions and response sequences, and can learn to make responses in different sequences.
Pigeons readily learn to respond in the presence of one simple stimulus and withhold responding in the presence of a different stimulus, or to make different responses in the presence of different stimuli.
Pigeons can discriminate between other individual pigeons, and can use the behavior of another individual as a cue to tell them what response to make.
Pigeons can remember large numbers of individual images for a long time, e.g. hundreds of images for periods of several years.
For further information: http://www.otago.ac.nz/news/news/otago029568.html
Photo: William van der Vliet
