From Nature:
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.
More here.