WASHINGTON - Even infants can tell the difference between naughty and nice playmates, and know which to choose, a new study finds. Babies as young as 6 to 10 months old showed crucial social judging skills before they could talk, according to a study by researchers at Yale University's Infant Cognition Center published in Thursday's journal Nature. The infants watched a googly-eyed wooden toy trying to climb roller-coaster hills and then another googly-eyed toy come by and either help it over the mountain or push it backward. They then were presented with the toys to see which they would play...