In that experiment, Ledoux conditioned rats to fear a bell by ringing it in time with anelectric shock until the rats froze in fear at the mere sound of thebell.

试验中，勒杜按时闹铃并且电击老鼠直到它们一听到铃声就吓得僵住。

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Just as Pavlov's dog learned to associate the sound of a bell ringing with dinnertime, rats can learn to associate flashes of light with how long they must wait to receive a sip of water.

MSN: Goggle-wearing rats show link between learning, rewards

Pavlov's early experiments on reflexes trained dogs to salivate at the sound of a bell, by ringing one every time they were fed with meat.

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