By CHRISTINE KENNEALLY

Faced with pictures of odd clay creatures sporting prominent heads and pointy limbs, students were asked to identify which “aliens” were friendly and which were not.
The students, at Carnegie Mellon University in Pittsburgh, were not told that the aliens fell naturally into two groups, although the differences were subtle and not easy to describe.
Some had lumpy, misshapen heads. Others had smoother domes. After students assigned each alien to a category, they were told whether they had guessed right or wrong, learning as they went that smooth heads were friendly and lumpy heads were not.
The experimenter, Dr. Gary Lupyan, added a little item of information to one test group. He told the group that previous subjects had found it helpful to label the aliens, calling the friendly ones “leebish” and the unfriendly ones “grecious” (both nonsense words), or vice versa.
When the participants found out whether their choice was right or wrong, they were also shown the appropriate label. All the participants eventually learned the difference between the aliens, but the group using labels learned much faster. Naming, Dr. Lupyan concluded, helps to create mental categories.
Language also has a significant role in seeing and remembering where objects are in space. Dr. Dedre Gentner at Northwestern University in Illinois and her colleagues conducted experiments on the spatial reasoning of hearing children and children who “home-sign.”
Home-signers have hearing parents, but they are congenitally deaf and have never been taught a sign language, said Susan Goldin-Meadow, an expert in homesign. The gestural language they develop is invented solely by themselves.
The children were shown two sideby- side boxes. Internally, each box was divided in three. In each space was a card.
During each trial, the experimenter took a card from the first box and showed the child that it had a special star on the back. Replacing it in the first box in the same space, the experimenter asked the child to find where the special card would be in the second box. Essentially, the children were asked to map the position of the target card in the first box to the same position in the second.
The researchers found that children without words for spatial relationships, whether young or home-signers, had much more trouble finding the special card in the second box than older hearing children who had learned the relevant words.
“By giving us a framework for marshaling our thoughts, language does a lot for us,” Professor Gentner said. “Because spatial language gives us symbols for spatial patterns, it helps us carve up the world in specific ways.”
Another subject in the debate over language and perception is color. Because languages divide the spectrum differently, researchers have asked whether language affected how people see color. English, for example, distinguishes blue from green.
Most other languages do not make that distinction. Is it possible that only English speakers really see those colors as different?
Some experiments suggested that color terms influenced people in the moment of perception. Others suggested that the language effect took place only after basic perception occurred. The consensus was that different ways to label color probably did not affect the perception of color.
Last year, Lera Boroditsky and colleagues published a study in The Proceedings of the National Academy of Sciences showing that language could affect how quickly perceptions of color are categorized. Russian and English speakers were asked look at three blocks of color and say which two were the same.
Russian speakers must distinguish between lighter blues, or goluboy, and darker blues, siniy, while English speakers do not have to, using only “blue” for any shade. If the Russians were shown three blue squares with two goluboy and one siniy, or the other way around, they picked the two matching colors faster than if all three squares were shades from one blue group. English makes no distinction between shades of blue, and English speakers fared the same no matter the mix of shades.
In two different tests, subjects were asked to perform a nonverbal task at the same time as the color-matching task. When the Russians simultaneously carried out a nonverbal task, they kept their color-matching advantage. But when they had to perform a verbal task at the same time as color-matching, their advantage began to disappear. The slowdown suggested that the speed of their reactions did not result just from a learned difference but that language was actively involved in identifying colors as the test was happening.
In another experiment, Dr. Lupyan, of Carnegie Mellon, showed subjects a series of chairs and tables . Some subjects were asked to press a button indicating that the picture was of a table or a chair. Other subjects pressed a button to make a nonverbal judgment about the pictures, for example, to indicate whether they liked them or not. Dr. Lupyan found that the subjects who used words to label the objects had more trouble remembering whether they’d seen a specific chair before than subjects who had only pressed a button in a nonverbal task.
Language helps us learn novel categories, Dr. Lupyan said. The problem is that after a category has been learned, it can distort the memory of specific objects, getting between us and the rest of the nonabstract world.