Young adults don’t always make great decisions. I myself did stupid things, which comes as a shock to my kids and husband, who know me as pretty, well, boring. Was my personality more reckless back then? Or could it have been because I lived much of life in a second language: French?

Knowing another language broadens your opportunities: the people you can talk to, the items you can read, the films you can watch, the countries you can comfortably communicate in. But studies suggest that it can also have unintended consequences when it comes to decision-making.

An exceptionally tough choice

To begin with an extreme example, consider this: If you had to kill one person to save five other people, would you do it? If I asked you in your native language, you would probably be pretty reluctant to push that one person off a bridge. (In a 2014 study of 725 undergraduate students who spoke two languages, 18 percent said they would do it.) If you were bilingual and I asked you in your other language, you might be much more willing. (According to the study, 44 percent would do so).

“The decision to sacrifice the person is often thought to be driven by a more controlled, deliberative process,” says Sayuri Hayakawa, an assistant professor in the Bilingualism and Psycholinguistics Research Group at Northwestern University and co-author of the study. Logically, it seems better to save five people than one.

“It’s basically emotionally aversive for you to go up to a person and physically push them off, more emotionally aversive than just not doing anything and letting five people die,” Hayakawa says. “And so, the idea is that using a foreign language dampens that aversive reaction, therefore allowing you to consider the more utilitarian cost-benefit analysis of ‘five lives is better than one.’”

In other words, you probably use more reason in your secondary language. In your original one, you probably use more heart.

The emotional key

“There’s still quite a bit of mystery in terms of exactly what it is that’s going on with the foreign language,” Hayakawa says. It could be that you’re tied up in processing the lesser-known words and phrases, which makes you “slow down and consider things a bit more carefully,” she says. However, “the main explanation so far is that using a foreign language just doesn’t have the same kind of emotional resonance that your native tongue does.”

This may come down to the learning method. Chances are good that you’ve lived a lifetime of rich experiences using your native language. Chances are good that you learned the other language somewhat later in life, maybe in a classroom.

“When language is learned and used in an emotional context, the emotional resonances accrue to the language,” says Catherine Caldwell-Harris, an associate professor of psychology at Boston University and author of various papers on the effects of foreign languages. On the flip side, a foreign language probably hasn’t had an opportunity to gain this emotional impact.

Caldwell-Harris co-authored another study, currently under peer review, that posed ethical dilemmas to 52 university students in Turkey who spoke English and Turkish, and another 201 for comparison who only spoke Turkish. For example, say you worked for a pharmaceutical company that developed a drug that could make a lot of money but had potentially life-threatening side effects. Would you offer it to the public anyway? In a native language, more people said they would be ethical and not sell it. In a foreign language, more said they would. Caldwell-Harris deduces this is because the foreign-language participants did not feel the emotions that would censor them from doing the unethical thing.

In a different study of 1,475 people, mostly university students, co-authored by Hayakawa, participants were less likely to cheat at a dice game in a foreign language, thereby “winning” less money. Here, the foreign-language speakers did the more ethical thing, which seems contradictory: If a foreign language makes you less emotional, wouldn’t you have a greater tendency to cheat during a dice game?

Although not involved in the dice experiment, Caldwell-Harris has given it much thought and explains it this way: In cases where no one is harmed, such as a dice game in a scientific study — what’s a little cash to a few researchers? — there’s a natural temptation to cheat. But in the foreign language, the participants didn’t feel the emotions that, in this case, would cause them to cheat.

“Using a foreign language,” Hayakawa says, “might detach you a little from your default ways of thinking” — whether those default ways are honest or not.

Betting, swearing and eating

The emotional factor also extends to risky behaviors. When posed in a foreign language, risks seem to appear smaller and benefits larger. Think of traveling by airplane. Two studies of individuals recruited by an Italian university concluded that the peril of crashing seems lesser and the benefit of getting somewhere desirable seems greater. Hayakawa co-authored a study of 321 university students that found that people speaking a foreign language took more risks when it came to gambling: They felt they were more likely to win than to lose, or were less concerned about losing.

The same thing applies to taboos such as swearing. To kids speaking a second language in a schoolyard, “taboo words feel like play money,” Caldwell-Harris says. Hayakawa explains further: “They just may not have the same kind of impact they would if you’re considering them in the language in which you first encountered those words.”

Language matters at the dessert table, too. When European researchers asked 100 German- and English-speaking restaurant diners to choose between a chocolaty dessert or a fruity one, those using a foreign language more often made the healthier choice. Caldwell-Harris, who was not involved in the study, says this is again tied to the weaker emotional impact of the choice: “They didn’t just go with their gut.”

Everyday implications

According to the Census Bureau, more than 15 percent of American adults speak a language other than English. Some may work in the medical field or have to make personal medical decisions, which could be unknowingly affected by language. Ditto in the legal field; in experiments involving 36 adult Spanish and English speakers, Caldwell-Harris found that using a nonnative language might skew the results of polygraph tests. Both experts mention people who work for the United Nations who might be attending meetings — and making decisions — in foreign-language settings. Language can also make advertising more or less effective, depending on whether you want the item to have an emotional tug (use the native language) or be thought about with care (use the nonnative one), based on a study that looked at more than 380 university students and community members in Belgium and the Netherlands.

“We’re still understanding it,” Hayakawa says. “I think there’s a lot of really interesting terrain to explore.”

And if you speak more than one language, should you alter your behavior to use a specific one in a specific context? Unless you’re choosing to experiment, Caldwell-Harris says no. “There are so many different reasons why you’re using one language versus another that are important and valid. I wouldn’t want to disrupt any of that.”

As for the stupid things I did in my youth, maybe I can chalk some of it up to using French. If risky acts hit me less emotionally when presented in my second language, perhaps they didn’t seem like such a bad idea. Then again, I could have been young and dumb.

Galadriel Watson is a freelance writer and author of two science books for kids: “Extreme Abilities” and the upcoming “Running Wild.”