She has spent hours on her hair and make up, bought a new outfit¹ and done her nails. So perhaps it is only fair that her date should pay for dinner。

Pretty women are less likely than plain Janes to offer to contribute towards the bill on a first date, research shows。

But they are not worried about the expense - it is likely to be because they believe their date should pay for the pleasure of being with them, according to researchers at St Andrews University。

The intriguing² finding comes from a study of 416 men and women who were asked to rate themselves for attractiveness, ahead of going on a series of hypothetical dates。

In each case, they were shown a picture of their ‘date’, told to imagine they had been for dinner together, and asked to decide who should pay for the meal。

They could decide to pay for the entire meal, nominate their date to pay or choose to split the bill。

The answers revealed that the good-looking women were less likely to want to contribute towards the costs. Handsome men were also reluctant to splash the cash。

Researcher Michael Stirrat said: ‘They quite literally³ bring more to the table, so they expect the other person to pick up the tab or expect to pay for the bill.’

Things, however, may change, if the man wants to impress。

The study, published in the journal Evolutionary⁴ Psychology⁵, showed that a man is more willing to pay for a good-looking woman。

Dr Stirrat said: ‘When a man offers to pay for the meal he is to some extent saying “I’m interested, I’d like a second date, I’d like to see you again”.’

But with women, the opposite is true. The study found that a woman expects a good-looking man to pay for her, perhaps as a way of making him invest in their future。

The researcher said: ‘When the woman lets the man pay for her, she is basically saying she’d like a second date.’

It also means that if a woman does insist on paying, or at least making a contribution, it may be a sign that the date hasn’t gone well。

Dr Stirrat said: ‘If he is less attractive, she’d rather split the bill.’

她花了好几个小时做头发、化妆，买了新衣服，还做了美甲。所以让她的约会对象付饭钱应该算是公平的吧。

研究发现，和相貌平平的女子相比，美女初次约会时主动提出要帮忙付账单的可能性较低。

不过美女们并不是担心这些花费。圣安德鲁斯大学的研究人员认为，这很可能是因为她们认为自己的约会对象应该为和她们在一起感受到的愉悦而付钱。

这一有趣的发现来自一项调查，研究人员请参与该调查的416名男性和女性为自己的魅力打分，然后进行一系列的“假想约会”。

研究人员给每个人看一张“约会对象”的照片，让他们想象自己和“约会对象”一起吃饭，并让他们决定谁该为这顿饭买单。

他们可以做出的选择有：自己付全部饭钱、让约会对象买单或平摊费用。

他们的答案显示，美女一般不愿意分担饭钱，帅哥也不大愿意给对方付账。

研究人员迈克尔•斯特拉特说：“在饭桌上，他们的可餐秀色确实会带来更多享受，所以他们期待对方付账，或认为对方要有这个心理准备。”

然而，如果男性想给对方留个好印象，情况可能就会不同。

这一发表在《进化心理学》杂志上的研究显示，男性更愿意为漂亮女人买单。

斯特拉特博士说：“当男人主动提出要买单时，在某种程度上他的意思是：我对你很感兴趣，我希望能有第二次约会，我想再次见到你。”

但是女人则正好相反。研究发现，如果一个女人希望一个帅哥给她付账，这也许就是让他为他们的未来投资的一种方式。

研究人员说：“如果女人让男人为她买单，她基本上就是在暗示希望能有第二次约会。”

这也意味着，如果一个女人坚持要买单，或至少是分摊费用，这可能就是约会失败的讯号。

斯特拉特博士说：“如果他没那么有魅力，她宁愿分摊费用。”