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,

I live in a city with mediocre public transportation, so I’m thinking of buying a car to help me get around. Should I buy a car with a stick shift or an automatic transmission?

—Joshua 

If you’re mostly driving in the city, then get a stick shift. This might sound odd, because urban driving with a stick shift means that your hands will be occupied much of the time with shifting the gears as you slow down, stop and accelerate. But that’s the point.

There are benefits to keeping your hands busy. In automatic cars, many drivers start texting at red lights, and when the light changes to green, they carry on texting and driving. In a manual car, you have to shift to start the car after a red light, so your hands aren’t free to text. This will certainly make driving in stop-and-go traffic more annoying, but it might also save your life and the lives of others.

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Dear Dan,

In my country, people don’t feel any shared ownership of public spaces. They drop litter outdoors or in the staircases of buildings, write on the walls and inside elevators, and destroy trees in public parks and gardens. I feel like it’s a cultural phenomenon. Is there any way to get people to behave more respectfully?

—Hanna 

As long as even a few people litter, we see trash around us, and we get the idea that it is socially acceptable to keep on behaving that way. With such a negative social norm, it’s very hard to change our own or others’ behavior.

With this in mind, I would recommend trying to get everyone to stop littering at the same time through some form of collective action. One example of such an approach comes from Rwanda, where President Paul Kagame has been credited with making Kigali one of the cleanest cities in the world through social action. Mr. Kagame created monthly collective cleanup days, when all citizens were asked to help make public spaces cleaner. He also elevated cleaning streets to an act under Rwanda’s traditional concept of umuganda, which roughly means: “coming together in common purpose to achieve an outcome.” And it worked.

Borrowing from Mr. Kagame’s example, perhaps you could get your neighbors to pick one Sunday when you all work together to clear the mess. This will make it clear to everyone how much of a mess there is and give you a clean starting point. Next, you could ask everyone to agree to keep the new norm and maybe try to link the cleanliness of public environments to their own sense of pride—a bit like making their own umuganda project.

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Dear Dan,

Three years ago, my youngest son was given a bitcoin as a gift for his bar mitzvah. Since then, he has seen the bitcoin’s value climb a few thousand dollars in a week and then go down again. He is considering selling, but he is afraid the digital currency will keep going up—or that it will soon go down and he will lose a bunch of money. What should he do? How can I teach him about being a wise investor?

—Nelson 

Here’s a basic principle for any investment: Don’t think about the price you paid for it. Instead, consider if you would buy it at its current price. Ask your son if he would buy a bitcoin at its recent price of around $10,000 (or whatever it is at that moment). If he says no, tell him that he should sell.

See the original article in the Wall Street Journal here.