Narrator: This is Science Today. Most parents
have no doubt heard about, and perhaps feared, that
time in a child's life coined "the terrible twos".
Alison Gopnik, a psychology professor at the University
of California, Berkeley says as exasperating as toddlers
can be during this rebellious period, it's a time
that's crucial to their cognitive development.
Gopnik: What we've done is a bunch of very
careful experiments to show that between the time
babies are born and the time they're about four, they're
changing their ideas about how other people work in
very regular and systematic ways.
Narrator: This is done during everyday interactions
Gopnik: So, you can think of the terrible twos
as being a kind of experiment that comes when you're
eighteen months old and you suddenly get this new,
startling hypothesis about other people which is,
"my God, maybe sometimes they don't want the same
thing that I do! Let me check this out and test out
ideas - especially about how other people work.
Narrator: For Science Today, I'm Larissa Branin.