Irrational Number writes:

Studies show that people actually start to keep long-term memories at
around age 2. That is based on studies using babies at different ages
and checking if they recall objects or rooms after two weeks.

Presumbly, though, it wouldn't be ethical to test the idea that younger
children may remember especially traumatic events! For that we're bound to
be limited to asking people who happened to suffer such events what they
remember and then trying to check authenticity.

Sidheag
DS Colin Oct 27 2003