Why we start understanding people after age of 4 decoded

Scientists have found why four-year-olds are suddenly able to understand that other people think and have a different world view - something most kids are not able to do till the age of three.
Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Germany and Leiden University in the Netherlands have shown how this enormous developmental step occurs: a critical fibre connection in the brain matures.
The researchers showed a three-year-old child a chocolate box that contained pencils instead of chocolates.
When the child was asked what another child would expect to be in the box, they answered "pencils," although the other child would not know this.

Only a year later, around the age of four years, however, will they understand that the other child had hoped for chocolates, researchers said.
Thus, there is a crucial developmental breakthrough between three and four years: this is when we start to attribute thoughts and beliefs to others and to understand that their beliefs can be different from ours.

Before that age, thoughts do not seem to exist independently of what we see and know about the world. That is, this is when we develop a Theory of Mind.
The researchers have now discovered what is behind this breakthrough.
The maturation of fibres of a brain structure called the arcuate fascicle between the ages of three and four years establishes a connection between two critical brain regions.

One is the region at the back of the temporal lobe that supports adult thinking about others and their thoughts, and the other is the region in the frontal lobe that is involved in keeping things at different levels of abstraction and, therefore, helps us to understand what the real world is and what the thoughts of others are.
Only when these two brain regions are connected through the arcuate fascicle can children start to understand what other people think.
Interestingly, this new connection in the brain supports this ability independently of other cognitive abilities, such as intelligence, language ability or impulse control.