Psychologists Determine Visual Working Memory Abilities of Three and Four Year Olds

Posted on June 28, 2013

3 year olds can hold 1.3 objects in visual working memory

Psychologists led by the University of Iowa used optical neuroimaging to quantify how much 3- and 4-year-old children are grasping when they observe what's around them and to learn what areas of the brain are involved. The study looks at "visual working memory," a cognitive function in which we stitch together what we see at any given point in time to help focus attention. In a series of object-matching tests, the researchers found that 3-year-olds can hold a maximum of 1.3 objects in visual working memory, while 4-year-olds can hold a maximum of 1.8 objects. Prior studies have found that adults max out at 3 to 4 objects.

John Spencer, psychology professor at the UI and author of the paper published in NeuroImage, said in the announcement, "This is literally the first look into a 3 and 4-year-old's brain in action in this particular working memory task. At a young age, children may behave the same, but if you can distinguish these problems in the brain, then it's possible to intervene early and get children on a more standard trajectory."

The researchers used functional near-infrared spectroscopy (fNIRS) for the studies. Spencer says fNIRS does not create a scary environment for the children being studied. There is no tube or loud noise. Spencer says, "You just have to wear a cap."

fNIRS records neural activity by measuring the difference in oxygenated blood concentrations anywhere in the brain. When a region in the brain is activated, neurons fire like mad and gobble up oxygen provided in the blood. Those neurons need another shipment of oxygen-rich blood to arrive to keep going. The fNIRS measures the contrast between oxygen-rich and oxygen-deprived blood to gauge which area of the brain is going full tilt at a point in time.

The researchers outfitted the youngsters with colorful ski hats that had fiber optic wires woven into them. The children played a computer game in which they were shown a card with one to three objects of different shapes for two seconds. After a pause of a second, the children were shown a card with either the same or different shapes. They then responded about whether they had seen a match.

The researchers say the test revealed that neural activity in the right frontal cortex is an important barometer of higher visual working memory capacity in both age groups. Another finding was that 4-year olds show a greater use than 3-year olds of the parietal cortex, an area of the brain that is believed to guide spatial attention.

Image: Sondra Cue, University of Iowa

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