Melissa and I realized recently that Sylvie is old enough to understand right and wrong and,

therefore, old enough to understand the concept of punishment. We came to that understanding, incidentally, when she started responding to "no" by grinning and then doing whatever it was we were telling her not to do - usually throwing her food on the floor.
So a couple of weeks ago we started giving her the "I'm going to count to three" shtick. That worked for a little bit, until she realized that she could let us get to three and nothing much would happen as a result. She started counting along with us, and then laughing. So now it's "one, two... three" and if she does not stop whatever it is she's doing she goes in "time out" - sitting on a chair in the corner of the dining room.
From the wailing that ensues at this point, you'd think she was sitting on a chair in the corner of the dining room over an open flame. Howling, yowling, choking and gagging, with the occasional "Mom-MEEEEEEEE!" thrown in to make Melissa feel really bad. Once she's sprung from time out, though, all of this stops abruptly. Lately she's taken to telling us, solemnly, "I's cay-in'" ("I was crying.") As if we hadn't noticed.
Anyhow, what prompted this mid-day post was a call I just got from Melissa. Sylvie is home from day care today with yet another cold. Melissa was in the kitchen, and Sylvie walked up to her and told her "Bay-bee's cay-in." She took Melissa's hand and pulled her into the dining room, where she'd placed her baby doll sitting up in the time-out chair. Assuming a stern tone, Syl shook her finger at the doll and said, "Five minutes. NO cay-in!"
So at least we know she understands the concept.