In a discovery that could shed light on the development of the human brain, University of Oregon researchers determined that infants as young as six months old can recognize simple arithmetic errors.
The researchers used puppets to portray simple addition problems. For example, in order to illustrate the incorrect equation 1 + 1 = 1, researchers showed infants one puppet, then added a second. A board was then raised to block the infant's view of both puppets, and one was removed. When the board was lowered, only a single puppet remained.
To gauge the infants' ability to detect the error, researchers recorded the number of seconds the babies spent looking at the puppet.
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According to the study, babies ranging from six to nine months old looked at incorrect solutions 1.1 seconds longer than correct ones. This extended viewing correlated with EEG measurements showing higher activity in a frontal area of the brain that is known to be involved in error detection in adults. The team's findings are published in the August 7th online edition of The Proceedings of the Natural Academy of Sciences.
"This brain system, in adults, allows us to monitor our own performance and even correct it," said psychologist Michael Posner, the study's lead author. "We know that infants can't necessarily correct it, but they do apparently have at least a start of that brain system."
Posner's study bolsters the results of a 1992 Yale study that measured length of gaze but did not include EEG measurements, an omission that led many scientists to doubt its conclusions.
Since the babies in Posner's experiment wore a net of brain-monitoring electrodes, the researchers could pinpoint enhanced brain activity following the presentation of incorrect solutions. Scientists previously thought that the brain system this data highlighted developed later, around two and a half years of age.
The findings could help scientists understand how early control systems are laid down in the brain and may eventually help them to analyze the genetic and experiential factors that influence early brain development, Posner said.
Patricia Kuhl, a professor of speech and hearing sciences at the University of Washington, believes studies like Posner's can reveal mechanisms in the infant brain that could help doctors monitor its development.
"The more we know about these infant systems," Kuhl said, "the more likely it is that we might be able to detect impairments early, and intervene while the brain is still being sculpted."
Posner added that his findings could also clue scientists into the development of the brain's representation of numbers.
"Some people have always thought that our number system is just something that's been created by humans and learned by us, then taught to our children," Posner said.
"But there seems to be a proto-number system—the beginning of a number system—that is available in other animals," he continued, "and apparently is present in infants as well."