What is an example of learning $($change in behavior$)?$

Wesley, age $2$ months, just started to smile at his parents.

Robert, age $28,$ quickly withdrawals his hand from the hot oven as the heat begins to burn his skin.

Ethan, age $18,$ sees an attractive woman, which causes his pupils to dilate.

Mandy, age $8,$ practices treading water so that she will be allowed to swim in her grandmother's swimming pool.