Here’s my Q&A column from the WSJ this week — and if you have any questions for me, you can tweet them to @danariely with the hashtag #askariely, post a comment on my Ask Ariely Facebook page, or email them to AskAriely@wsj.com.

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Dear Dan,

People in my office drink a lot of coffee, which means a lot of mugs pile up in the sink. What happens is that one person leaves a dirty mug, and the next person to use the kitchen doesn’t want to clean that mug along with their own, so they leave theirs in the sink as well. Soon the sink is overflowing with these dirty dishes, and no one wants to take the time to wash all of them. If everyone just washed their own mug there wouldn’t be a problem, but what can we do to enforce this rule?

—Oran 

As you observed, the heart of the problem is the first mug: If someone observes a dirty dish in the sink, they are less likely to wash their own, and so the problem is compounded over time. In my lab at Duke University we had the same issue, and we tried two different solutions. First, I put a picture of myself above the sink, looking directly into peoples’ eyes, with the message “Please don’t leave your dish in the sink.” This was meant to remind people of the importance of the rule, but while it helped a little, it didn’t eliminate the problem. Our next step was to issue everyone in the office a mug with their name written on it, so that it would be obvious who was responsible for leaving a dirty mug in the sink. The threat of being publicly embarrassed managed to solve the problem almost completely.

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Dear Dan,

When I’m using the urinal in a public bathroom, it seems to me that I finish much faster when I’m alone than when someone is standing at the urinal next to me. Do you think this is a real phenomenon, or does it just feel that way because I’m more self-conscious when someone else is nearby?

—Joe 

I once conducted an experiment on this subject on the MIT campus, in which a research assistant would enter a public men’s room alongside unsuspecting students. Sometimes he would use a urinal right next to a student, while other times he would leave a free urinal between them. We found that when men have someone using the urinal next to them, it takes them longer to start urinating, but once they start they finish faster, as if they’re trying to get it over with and leave quickly. So you’re not imagining it: Being observed in the bathroom does make the experience more stressful.

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Dear Dan,

Recently I’ve been bombarded with requests for donations from various charities and political groups. Is it better to donate larger amounts of money to a few causes or smaller amounts to many?

—Barbara 

There are many ways to define “better,” but if you’re asking what’s better for you personally, I would recommend making smaller, more frequent donations. Every time we help others, even a small amount, we get a boost of positive emotion, so you would enjoy this benefit more often. And because it’s psychologically harder to part with large amounts of money, you will enjoy making small donations more, which means you’re more likely to make giving into a habit.

See the original article in the Wall Street Journal.