新托福考试阅读练习：MicePreferTreatsTheyWorkedHardertoGet

会计考友

　越是辛苦努力得到的成功人越觉其珍贵，也越懂珍惜。对于可爱的实验小鼠而言也是如此。  
( E( \- {' |: n2 t/ Q1 a3 C　　Maybe your dad said, “The harder you work for something, the more you’ll appreciate it.” Well, father really did know best. Because a new study finds that the harder mice have to work for a treat, the better it tastes. The research appears in the Proceedings of the Royal Society. [Alexander Johnson and Michela Gallagher, "Greater effort boosts the affective taste properties of food"]

, P, u. ]4 B3 b　　Mice were trained to push levers to get either of two rewards. Press one lever, out comes a drop of sugar water. Press the other and they get a drop of different tasting sugar water.
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　　Then things got interesting. For one of the treats, scientists gradually increased the amount of effort required for the payoff—from one lever-press to five, then 10, then 15. So by the end of the session, one type of sugar water cost 15 times more effort than the other.

, G. y, j# S( w' ]4 R　　The mice then retired to their home cage where both treats were freely available. And they showed a strong preference for whichever reward they’d worked harder to obtain. Based on how fast the mice sipped, they appeared to find the costlier sugar water more tasty.

1 V* p$ k. h% x+ I  q3 F: H　　Which makes evolutionary sense. An animal wouldn’t survive if a little hard work left a bitter taste in its mouth.