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The small black fish swim around the tank; gracefully gliding back and forth with little discernible pattern.
Then, barely audible over the watery whirr of the marine laboratory, a low buzz sounds.
And a few seconds later, the scene is transformed as the fish crowd into a small area, corralling themselves into a tightly packed ball.
They are awaiting a reward.
"Now we drop some food into the feeding tube," says Scott Lindell, who is running the experiment.
"And voila, they are satiated and happy." |
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Bass tones
Mr Lindell is the director of the scientific aquaculture programme at the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts. And for the last few years, he has been training fish.
It's a Pavlovian response, he explains.
Just as 19th Century scientist Ivan Pavlov conditioned dogs to associate the sound of a bell with the prospect of food, Mr Lindell's black sea bass associate a 280Hz tone emitted from an underwater speaker with food, and respond by gathering in a partitioned "feeding zone". |
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