orichalcum

OK, so-- you take a baby at the crawling stage and put him on a wooden table that has a glass extension at one end, so that it looks like it ends (like a cliff) but it's actually glass. The mother stands at the far end of the glass segment. The baby crawls toward her. He always hesitates at the apparent cliff, but if the mother smiles and makes an encouraging face, he crawls right onto the glass. If the mother looks frightened or shocked, he stops and won't proceed. Basically, it's an experiment for facial communication of information to babies. But it also implies that they will to some extent go at your whim!