Children younger than 12 do not integrate information to understand the world as adults do, reports a new study from University College London and Birkbeck, University of London.
This not only applies to the combining of different senses, such as sound and sight, but also to the varying information the brain receives while viewing a scene with one eye as compared to both eyes.
Dr. Marko Nardini, UCL Institute of Ophthalmology, and lead author said, “To make sense of the world we rely on many different kinds of information. A benefit of combining information across different senses is that we can determine what is out there more accurately than by using any single sense.”
“The same is true for different kinds of information within a single sense. Within vision there are several ways to perceive depth. In a normal film, depth is apparent from perspective, for example in an image of a long corridor. This kind of depth can be seen even with one eye shut,” he added.
In the study, scientists observed how children and adults combine perspective and binocular depth information. Results show that the ability to use the two kinds of depth information together does not take place until the approximate age of 12.
Children and adults were given 3D glasses and asked to compare two slanted surfaces in order to judge which was the flattest—given perspective and binocular information separately, or both together.
It was not until 12 years that children combined perspective and binocular information, as adults do, which led to more accurate judgments.
Interestingly, there is a potential problem when the brain is capable of combining sensory information. Some adults experience ‘sensory fusion,’ an inability to separate the individual pieces of information feeding into the overall perception.
Scientists wanted to find out if children—because they separate their incoming information—were able to avoid sensory fusion. To answer this question, researchers gave the participants special 3D discs in which perspective and binocular information sometimes disagreed.
In the results, adults performed poorly at determining whether or not the slant of two discs was the same or different. On the other hand, 6-year-olds had no trouble in pinpointing differences between discs of this kind. This proves that 6-year-olds can evaluate visual information in ways that adults cannot.
Professor Denis Mareschal, from the Centre for Brain and Cognitive Development at Birkbeck, who co-authored the study said, “Babies have to learn how different senses relate to each other and to the outside world. While children are still developing, the brain must determine the relationships between different kinds of sensory information to know which kinds go together and how.”
“It may be adaptive for children not to integrate information while they are still learning such relationships, those between vision and sound, or between perspective and binocular visual cues.”
Scientists hope to use functional magnetic resonance imaging (fMRI) to determine the brain changes that take place when they begin to combine visual information in an adult-like way.
The study is published in the Proceedings of the National Academy of Sciences.