What motivates us to give our money away? Many would say we donate to charity for the satisfaction of knowing we helped our fellow man. But research suggests we may be more influenced by guilt, self-interest and sometimes, to look better to the opposite sex.

It's the kind of research that should interest relief agencies that are struggling to understand why people are not donating more to help the millions of Pakistanis affected by flooding this summer.

Only about 70 per cent of the $460 million the United Nations is hoping for for Pakistan relief has been pledged so far. And this figure may need to be revised higher as the UN says it underestimated the number of people suffering from the disaster.

An Angus Reid Public Opinion poll released this past week revealed that the number of Canadians who have donated to Pakistan so far is only a fraction of the number who donated to Haiti shortly after its earthquake in January.

While two-in-five Canadians (38 per cent) reported donating to Haiti, only four per cent have donated to help Pakistan. So why do we give to one need and not to another -- and why do we give at all?

Is self-interest a motivator?

One study found that we are motivated to give if it'll make us look good. Yale economist Dean Karlan found in a 2009 paper titled "Hey Look at Me" that people were more likely to donate to an alumni group when offered public recognition in a newsletter. Furthermore, when told that donors would be separated into "circles" based on amount given, people were more likely to donate more to reach a higher level.

So perhaps, when we donate, we're looking for a little something in return? University of Chicago economist John List would likely agree.

List has long been fascinated with the psychology of charity. He helped conduct an experiment that found that the most effective door-to-door fundraising method was selling lottery tickets in which a portion of the sale went to charity. The least effective method? Simply asking for money.

That same study yielded another fascinating finding: sex sells, even when it comes to charity.

The researchers found that when they used a more physically attractive woman to go door-to-door, they increased average donations by 50 to 135 per cent compared to an an "average-looking" solicitor -- largely because men who answered the door were more likely to respond to the request.

Charity needs a personal face

If that study doesn't convince you that the rules that govern how people shop often go out the window when it comes to how they give away their money, or that charity donators are motivated less by rational thinking than by emotion, consider the work of University of Oregon psychology Prof. Paul Slovic. He helped conduct a study in which people were asked to donate up to $5 to the charity Save the Children.

One group was shown a picture of a malnourished African girl named Rokia and learned of her personal plight; another group saw Rokia's picture and then were told facts about the larger plight of starving African children; another group heard just the statistical facts. Can you guess which group donated more?

Of course, it was the group that was told a story about Rokia, because that appealled to their heart.

Perhaps that's why more Canadians are not donating to Pakistan: they haven't seen enough of the personal side of this disaster.

Karen Palmer, a spokesperson for Oxfam Canada and the Humanitarian Coalition, a network of four leading aid organizations (CARE Canada, Oxfam Canada, Oxfam-Quebec and Save the Children Canada), says she believes the greatest problem with garnering donations for Pakistan relief is that Canadians are not seeing enough images of the disaster.

Palmer notes that not many TV outlets have been able to broadcast images of the disaster the way they could with Haiti for example. That's in part because of security issues and difficulties accessing the areas most affected.

But she also notes that floods that wipe out rural areas don't offer good visuals, and don't provide the same before-and-after destruction that an earthquake creates.

"In Haiti, you could see the toppled buildings. In this, as the waters recede, it doesn't look as bad as Haiti looked after its earthquake. It's a much different visual," Palmer told CTV.ca.

Story of suffering not getting told

And it's images of suffering that Canadians typically respond to, she says.

"When people see… how great the devastation has been, I think that actually stirs people's sympathies, and really gets people thinking compassionately about, ‘What would I do if I were in a similar situation?' I think we're just not seeing that personal face to this disaster," she says.

Palmer says there are other reasons for the low donations, including the fact that the death toll in Pakistan has been low, even though the number affected is high. (Seventeen-million Pakistanis are affected -- more than the total affected in Haiti and in the South Asian tsunamis combined.)

Jaideep Mukerji, vice president of public affairs at Angus Reid says he thinks a key problem for Pakistan is one of public perception.

That's illustrated by his poll's findings on whether Canadians thought their government has done enough to help the victims in Pakistan.

When Angus Reid asked the same question of Canadians in the weeks after the Haiti earthquake, only about 9 per cent thought Ottawa had done too much to help. With Pakistan, a full 20 per cent of respondents replied the same way.

"So even though in this disaster, on a dollar basis, Canada is doing much, much less, the perception is the government is doing too much," Mukerji said. "And again, I think that's because Pakistan doesn't have quite the same image as Haiti."