The experiments this op-ed describes are really neat. I especially like the one that demonstrates the importance of "practice what you preach." Here's another cool experiment related to social/moral development, which you can perform on your own kid: Have two grown-up friends each show your baby a toy. The first friend should offer the toy to your kid but then retract the offer and keep the toy to himself. The second…
I don't understand this at all. At 21 months, a toddler can walk and talk, and you can play keep away with them for fun. I don't know what it means to drop a toy out of reach. Do you drop it on a high counter or something?
One way to replicate this at home, albeit imperfectly, is to place your toddler in a high chair, so that if you drop the toy on the floor, she is unable to reach it.