One sense at a time

Unlike adults, children don't integrate different types of sensory information.

Look and feel: kids use only one or the other to tell how big building blocks are. Credit: Punchstock

Adults readily integrate sight, sound, smell, taste and touch in their everyday lives without a second thought. But research is revealing that this is not the case with children. Two new studies hint that children under the age of eight only use one sense at a time to judge the world around them.

Previous research has demonstrated that adults can easily combine and rank the value of the information that they gather from their senses. For example, a man looking for a flute player in a crowded room can use sight and sound to do so, relying more on sight in a room full of background noise.

David Burr of the University of Florence, Italy, and Marko Nardini at Birkbeck College, University of London, UK, each led a team of researchers to explore whether children possess this ability.

Burr’s group asked children between the ages of five and ten and adults to determine which of two blocks was taller than the other. While making their decisions, participants were allowed to either touch the blocks, look at the blocks, or do both. The team report in Current Biology that adults and children eight years of age and older were better at this task when they could both see and touch the blocks. Their ability fell when they were denied one of these two senses.

But children under the age of eight did not show this difference at all. They performed nearly identically in the task when given just sight, just touch, or both to work with1.

“We have long known that in the passage from childhood to adulthood individual senses improve in accuracy, but it now seems that learning to integrate the senses is as important as improving them individually,” says Nardini, the author of the second study.

Rocket science

Lost in space: only adults do more poorly navigating in the dark if denied visual cues. Credit: Nardini

Nardini and his colleagues gave 28 children aged four to eight the task of returning an object to its original place in an arena. The arena was completely dark, except for three glowing landmarks around the edge in the shape of a moon, a lightning bolt, and a star. The children were asked to play a game: they had to pick up a toy rocket and then walk around the room to fill it with toy fuel, collect a toy alien to be the passenger, and countdown from ten for lift-off. They then had to return the rocket to where they had originally found it. The entire experiment was repeated for 17 adults who were given (somewhat amusingly) the same instructions.

Adults successfully brought the rocket back to within 26 centimetres, on average, of its starting place, while the children had less than half that accuracy. But things got interesting when actions were taken to confuse the participants’ senses.

In one case researchers turned off the landmark lights, forcing participants to rely solely on their internal sense of direction in the dark. In another they put subjects in a spinning chair, (described as a ‘space pod’) before letting them replace the rocket, forcing them to rely on visual landmarks only.

Adults did more poorly in both cases, nearly reduced to the same ability as the children. But the children showed no reduction in their ability when denied either the landmarks or their sense of direction. Having one or the other was just as good as having both2.

“This is a clever new way to explore children’s ability to integrate information,” says developmental cognitive psychologist Virginia Slaughter at the University of Queensland in Brisbane, Australia. The results suggest that children don’t integrate, but instead “alternate” between sources of information, she says.

The results could potentially explain some common childhood situations. “Children get lost so easily,” notes Nardini. “While there may be many reasons for getting lost when young, one striking one could be this inability to integrate information.”

References

  1. 1

    Gori, M., Del Viva, M., Sandini, G. & Burr, D. C. Current Biology, 18, 694-698 (2008).

  2. 2

    Nardini, M., Jones, P., Bedford, R. & Braddick, O. Current Biology 18, 689-693 (2008).

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Kaplan, M. One sense at a time. Nature (2008). https://doi.org/10.1038/news.2008.796

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