Baby monitor.
Pinker
S
S
D001900:Boston; D002657:Child Development; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D002666:Psychology, Child / Q000266:history*; D012108:Research Personnel / Q000266:history