近年來，媒體偏頗（media bias）的現象愈來愈引起經濟學家的注意。本文指出，即便媒體本身的意識型態中立，他們仍然有誘因為了迎合閱聽眾的口味而帶著立場扭曲他們的報導。比較有趣的是，在這篇文章中，即使沒有在文獻中提到的價格競爭或是媒體考量本身聲譽的效果，在一些普遍的情況下，新聞媒體的意識型態仍會傾向兩極化。另外，我們也指出，這樣的兩極化現象，會透過媒體與閱聽眾之間的交互影響輕易地深化。 / Media bias has been attracting more and more attention of economists in recent years. This essay shows that, even the media firms are ideologically neutral, they still have incentives to slant their news to cater to the audience or readers. An interesting feature of this paper is that, even though without reputation and price competition effects proposed in the literature, the ideology of news reported is apt to be polarized under some situations which are very common in reality. We also show that polarization could be easily deepened through some interaction between media firms and news consumers.