"The bottom line is that it's so new we don't know if it's good, bad or otherwise, but there is a lot of other research that shows the main learning and sustenance for young children — particularly under 2 — comes from their relationships, particularly with their parents and whomever takes care of them," said Tovah Klein, director of the Barnard College Center for Toddler Development. It is a hot-button topic among parents and pediatricians and the makers of electronic devices.