In a task based on switching between two sets of rules, 5-year-olds score highly, while 4-year-olds and chimpanzees lag behind
18 January 2023
By the age of 5, children are much better than chimpanzees at shifting their attention from one set of rules to another. The findings add to evidence that unique cognitive changes occur in humans before they reach 5 years of age.
Like memory and self-control, switching between “mental sets”, such as rules or instructions, is a core cognitive ability developed in young age. It lets us quickly adjust to changes in the environment, for example, choosing a different way to get somewhere when our route is blocked by roadworks.
To compare attention-shifting abilities in primates and humans of different ages, Eva Reindl at the University of St Andrews in the UK and her colleagues designed a set of tasks using cups that concealed rewards.
Children and chimpanzees were trained to determine which of four cups on two different sets of shelves contained a reward — stickers for children and bananas for chimps. On the green shelves, a green cup held the treats, while on the blue shelves, it was a pink cup.
When they had to switch from one set of shelves to another, chimpanzees successfully selected the right cup 52 per cent of the time. This is comparable to 3-year-old children, who had a success rate of 50 per cent, and 4-year-olds, who chose correctly in 59 per cent of cases.
Among 5-year-olds, the success rate was far higher, at 80 per cent. “There’s definitely something going on from 5 years of age,” says Reindl.
The improvement on the task with age in children is probably due to biological changes such as the development of the brain’s frontal lobes, says Reindl.
But cultural development may play a role too. Just as adults voice phone numbers or directions aloud to remember them, language may have helped the older children to switch between the two rules.
Most of the errors made by the children and the chimps were due to applying the rule for the wrong set of shelves, but for chimps, 32 per cent of the errors were random, compared with 23 per cent in 4-year-old humans and 27 per cent in 3-year-olds.
“The chimps sometimes picked [cups] that were not relevant at all, suggesting that they hadn’t formed such strong attentional sets in the first place,” says Reindl.
Although biases – such as the children being tested by their own species – make it difficult to compare humans with apes, the study’s general findings are robust, says Frans de Waal at Emory University in Atlanta, Georgia.
“It’s hard to argue with the conclusion that 5-year-old children do better than younger ones and better than chimpanzees of various ages, including adults,” says de Waal.
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