We gave her a handout which was about a really simple technique, using little mood faces to show what sort of mood you're in; smiley faces if you're happy, that sort of thing.

We do not normally hold some facial expressions for long periods and natural expressions (notably smiles) have definable durations, typically between about half a second and four seconds.

Most of the dolls out there are just plain happy or expressionless and that’s what makes them hollow and one-dimensional.