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’m seeing many more surveillance cameras in shopping malls, restaurants, roads and even my workplace. I doubt that anyone is watching all these acres of footage, so why should anyone care about being recorded? Won’t the cameras’ ubiquity undermine their effectiveness?

—Bruce 

Don’t be so sure. Even if no one is watching the cameras’ video in real time, authorities can still use it after a crime has occurred to figure out who did what to whom. So please don’t start behaving badly just because you’re seeing so many cameras around.

Moreover, from a psychological perspective, surveillance cameras also provide a good mechanism for reminding us about morality. One of the most powerful motivators of honest behavior is our own moral self-evaluations (known to experts as “self-concept maintenance”). When we have other people (or cameras) around, they remind us about the people we want to be, which spurs us to behave more nobly.

An early demonstration of this principle came from research in 1976 by Edward Diener and Mark Wallbom, published in the Journal of Research in Personality, who showed that mirrors reduced academic dishonesty in students by making them more self-aware. In their experiments, students who took an exam in a room decked out in mirrors were less likely to keep writing after the bell rang than those who took their tests in a normal classroom. Similarly, surveillance cameras—particularly if they’re clearly observable—should increase self-awareness and, with it, better behavior.

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Dear Dan,

My closest friend since childhood recently betrayed me, after decades of trusting friendship. She has apologized sincerely, but all the confidence I had in her is still tainted. Is it rational (or helpful) to forgive people who have hurt us?

—Jamie 

While it isn’t clear whether your friendship can fully recover from this incident, you clearly would be better off if you could forgive your friend. Research has shown that our health improves when we free up mental space from grudges and hate.

In a study published in 2003 in the Journal of Behavioral Medicine, Kathleen A. Lawler and colleagues interviewed 108 college students about a time when a parent or friend had deeply hurt them and measured their blood pressure at several points during the conversation. Subjects who forgave their betrayers had lower levels of blood pressure than those who hadn’t been as lenient. Even more important, college students who had more forgiving personalities overall turned over to have lower blood-pressure levels and heart rates.

Of course, forgiveness isn’t easy, but if you can pull it off, it brings real benefits.

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Dear Dan,

I go out to dinner with my husband once a week, and every time, we promise to order something healthy—but when we see the menu, we get tempted and order something less virtuous but tasty. Any advice on how to show more resolve?

—Aimee 

You are describing a classical case of temptation. Before you get to the restaurant, you’ve settled on a certain idea of how you want to behave—then you get tempted, and afterward, you regret your indulgences. So how can you override temptation? Just order for each other. When we order for our significant other, we aren’t tempted by taste and can instead think about their health—which is also what our spouse would want a few hours later.

See the original article in the Wall Street Journal.