In an extension of their recent study that found a relationship between learning a foreign language and rational thinking, researchers at the University of Chicago are looking for situations in which using a foreign language can, alternatively, impair decision making.

Psychology researchers published work this May in Psychological Science examining how thinking in a foreign language results in increased rational thinking and reduced decision biases.

The paper, “The Foreign-Language Effect: Thinking in a Foreign Tongue Reduces Decision Biases,” authored by U of C psychology professor Boaz Keysar and graduate students Sayuri Hayakawa and Sun Gyu An, tested the hypothesis that using a foreign language causes people to be less emotional in their decision making and reduces their biases. Their research supported this hypothesis.

Speaking from his own experience as a native Hebrew speaker who has also learned some Arabic, French, Italian, and Spanish, Keysar explained that when speaking a language other than your native tongue, “you are more deliberate; you are slower, more anxious, but really it forces you into a more deliberative mode of thinking. Your decisions become more systematic.”

Now, researchers have decided to take a step back and examine when this systematic thinking actually impairs our decision making.

“The reason we think it could impair decision making is that there is a very good reason for us to have an emotional system,” Keysar said. “We evolved to have it in order to survive. There are cases where you really do want to be connected much more with your emotional reaction because your emotional reaction helps you make the decisions. Under these conditions we expect people to do better in the native tongue than in the foreign language.”

The researchers believe that research on the effects of learning a foreign language on decision making can provide insight on how and why people make decisions.

“It helps us predict people’s behavior better, especially at the aggregate level,” Hayakawa said. “The main point is that using a foreign language can be more or less useful than using a native language, depending on whether or not emotions are useful for your choices.”