This news release is available in French.
In comparing amounts of things -- be it the grains of sand on a beach, or the size of a sea gull flock inhabiting it -- humans use a part of the brain that is organized topographically, researchers have finally shown. In other words, the neurons that work to make this "numerosity" assessment are laid out in a shape that allows those most closely related to communicate and interact over the shortest possible distance.
This layout, referred to as a topographical map, is characteristic of all primary senses -- sight, hearing, touch, smell and taste -- and scientists have long assumed that numerosity, while not a primary sense (but perceived similarly to one), might be characterized by such a map, too.
But they have not been able to find it, which has caused some doubt in the field as to whether a map for numerosity exists.
Now, however, Utrecht University's Benjamin Harvey, along with his colleagues, have sussed out signals that illustrate the hypothesized numerosity map is real.
Numerosity, it is important to note, is distinct from symbolic numbers. "We use symbolic numbers to represent numerosity and other aspects of magnitude, but the symbol itself is only a representation," Harvey said. He went on to explain that numerosity selectivity in the brain is derived from visual processing of image features, where symbolic number selectivity is derived by recognizing the shapes of numerals, written words, and linguistic sounds that represent numbers. "This latter task relies on very different parts of the brain that specialize in written and spoken language."
Understanding whether the brain's processing of numerosity and symbolic numbers is related, as we might be tempted to think, is just one area
|Contact: Natasha Pinol|
American Association for the Advancement of Science