Even in the cradle, babies as young as 5 months have a rudimentary ability to add and subtract, according to a study being published Thursday.
The study seems to show that infants know when simple calculations such as one plus one or two minus one are done correctly or incorrectly. The infants indicated awareness that a wrong answer was given by staring longer at the unexpected results.
Researchers say they believe that the finding, combined with corroborating research on infants and animals, indicates that, however modest, humans have an innate, biologically determined propensity for learning mathematics, as has been proposed for language.
Of more immediate interest to parents, the research sheds new light on the moment when a baby first learns to count.
The findings ”mean that when parents start teaching babies numbers, they are not teaching the baby to recognize quantities per se, but rather the names-one, two, three-we use for something the baby already knows,” said Dr. Mark Strauss, a developmental psychologist at the University of Pittsburgh.
The new finding, reported in the journal Nature by Dr. Karen Wynn, a developmental psychologist at the University of Arizona, is ”notable in the history of developmental psychology,” Dr. Peter Bryant, a psychologist at Oxford University, wrote in a commentary in the journal.
But some experts disagree. ”This study doesn`t necessarily show the infants understand math,” said Dr. Patricia Bauer, a psychologist at the University of Minnesota.
”It could simply mean they understand that the display had changed in a way that violated an expectation, but not that they understood the change in quantity.”
In interviews, other experts on infant development said the findings of a simple mathematical ability in babies were supported by other research.
In the study in Nature, Wynn employed a well-established and widely used method for measuring whether infants find an event unexpected or not: babies will stare longer at something that is surprising than at something that meets their expectations or is familiar.
For years, researchers have taken advantage of this phenomenon to study babies too young to indicate their mental reactions in other ways.
To present the babies with math problems, Wynn used 4-inch-high figurines of Mickey Mouse. For example, for the problem one plus one, she showed the infants one figurine, then put up a small screen that hid it. Then, in full view of the infant, a hand placed another figurine behind the screen.
Finally, the screen was pulled away to reveal both figurines. Video monitors recorded how long the baby looked at the two Mickey Mouse figurines. Using the same procedure, the researchers sometimes would pull the screen away to reveal a false answer, for example, only one figurine, or three, when there should have been two.
In these cases, the infants gazed for several seconds longer, indicating that they had anticipated the correct answer and were surprised by the different number.
The researchers said the infants` response did not simply reflect an expectation that there would be more or fewer objects. They noted that in the one-plus-one experiment the infants stared longer when the screen was pulled away to show three objects than when there were two.
This indicated that it was not the expectation of more objects but rather the numerical answer that dictated the response.
The findings, Wynn said, indicate there may be an innate structure in the mind for understanding numbers, just as the linguist Noam Chomsky has proposed for language.
Wynn`s results are not the first to suggest a rudimentary mathematical ability in infants, though they are noteworthy because her procedures were rigorously designed to answer doubts expressed about methods in earlier studies.
