Psychology's 'lost boy' lost no more

摘要

You'll have heard of Pavlov's dogs, conditioned to expect food at the sound of a bell. You might not have heard that a scarier experiment - arguably one of psychology's most unethical -was once performed on a baby. In it, a 9-month-old, at first unfazed by the presence of animals, was conditioned to feel fear at the sight of a rat. The infant was repeatedly presented with the rat as someone struck a metal pole with a hammer until he cried at merely the sight of any furry object.