Child-rearing, it turns out, doesn’t seem to have much to do with why some people end up with high scores on the scale and give generously to organizations that help people in faraway lands. Mr. McFarland, who said that he had been repeatedly audited by the Internal Revenue Service because of his outsize donations to Doctors Without Borders and Human Rights Watch, pointed to other research suggesting that memorable experiences might begin to shift people’s views.

For those of us who want to be more like Mr. Singer but end up giving mostly locally, international travel may be one way to shift our focus. But there is plenty to do at home, too. Jen Shang, a professor of philanthropic psychology at Plymouth University in England who gives to a children’s hospice in Indonesia called Rachel House, suggests that many kinds of direct action can help shift our orientations. Amnesty International’s online petitions may be one place to start.

One of the biggest objections to giving more to global organizations tends to be our desire not to turn our back on our neighbors. Here, a “Give Global, Act Local” approach may help, where you make up for any contribution declines with more hours of volunteer work in the community. When I suggested this to Mr. Singer, he grumbled a bit about the idea of a lawyer billing $500 an hour volunteering instead of giving away that money, but he allowed that the overall notion made a fair bit of sense.

My family’s local-global charitable allocation is still nowhere near Mr. Singer’s, even though we find his logic compelling. Our hang-up is this: We have a long history of being helped ourselves. My wife comes from a family of Holocaust survivors, and volunteers and donors lined up to assist them when they arrived in the United States.

I got through middle and high school as well as college thanks to others who gave money so that I could be on financial aid. My mother was lucky and survived premenopausal breast cancer. Giving to help refugees, scholarship children and others grow up with their mothers after a cancer diagnosis feels like an act of gratitude that is not optional.

So what is the optimal allocation for me — and all of us — who have had the rope thrown back for us? Mr. Singer pushed back on the idea of giving a lot to breast cancer organizations, for instance. He noted that we can save many more lives far more effectively and cheaply with preventive measures and medicines that already exist.

I pressed him further to put a number on it. “I find it hard to tell you what to do,” he said. “If you feel you have a strong case for this, make it up to 25 percent or something, if you like. But I would still keep the majority of your money for use where it will be maximally effective and hope that you’ll feel comfortable repaying your debts of gratitude with the remainder.”

The right answer for my family may be a different allocation. Still, there is a lot more that all of us can do for the people who have the least in the world. And our collective 4 percent allocation toward them should give everyone with a conscience something to think about.