Kids exhibit goal-oriented behaviour as early as age 3 say researchers at the University of Cambridge.
The study found that by around the age of 3, children appear to shape their behaviour in response to the outcomes they've come to expect.
Anticipated outcomes that kids value, move them to act more than outcomes that they don't value - a hallmark of emerging autonomy.
For the study, the researchers trained 72 kids between 18 months and 4 years old, divided into three 10-month age bands (averaging 1.3 to 2.2 years, 2.3 to 3.075 years, and 3.08 to 4 years) to touch a red or green butterfly icon on a touch-screen display to see different cartoon video clips.
The children came to link one butterfly with one cartoon sequence and the other butterfly with another.
The researchers then devalued one of the outcomes by showing that sequence repeatedly, until the children became bored with it.
As a result, the less-viewed cartoon clips became, by contrast, more interesting and valuable.
The researchers then re-tested the kids, who should now have associated one butterfly with a valued cartoon and the other butterfly with a less-valued cartoon.
They found that relative to the younger children, those who were 32 months (nearly 3 years) and older touched the butterfly for the less-valued cartoon significantly less often than they touched the butterfly for the more novel cartoon.
During that test, the cartoons were not actually presented; the children had to rely on their memories of which butterfly icon produced which cartoon.
The study therefore showed that the actions of the older children behaviour depended on the current values of the outcomes, whereas the actions of the younger children did not.
Ulrike Klossek, PhD, co-author of the study, pointed out that although all the children were sensitive to changes in outcome value and preferred the less-repeated cartoon, only the older children actually acted in a way that, based on their experience, would get them their favourite cartoon.
The researchers said that although adults take goal-directed action for granted, it's not in us from birth but rather emerges in a normal developmental timeline that appears to emerge roughly between the ages of 2 and 3 years.
"One possible interpretation is that the period between 2 and 3 years of age brings about a transition in behavioural control from stimulus-outcome learning to fully intentional goal-directed action," the researchers said.
By age 3, kids can pursue specific goals even if they cannot directly sense those goals, which may now be more abstract.
The older kids are sensitive to how goals change in value, begin to internalise their relationship to and control over events, and start to act in ways that will help them achieve the goals they value most - such as more exciting cartoons.
"This capacity [to internalise one's control over the environment] is an important component of becoming a fully autonomous intentional agent," the researchers said.