Research Article: Deliberate reasoning is not affected by language

Date Published: January 31, 2019

Publisher: Public Library of Science

Author(s): Martin Jensen Mækelæ, Gerit Pfuhl, Valerio Capraro.


Millions of people use a second language every day. Does this have an effect on their decision-making? Are decisions in a second language more deliberate? Two mechanisms have been proposed: reduced emotionality or increased deliberation. Most studies so far used problems where both mechanisms could contribute to a foreign language effect. Here, we aimed to identify whether deliberate reasoning increases for problems that are devoid of any emotional connotation when using a second language or having to switch between native and second language.

We measured deliberate reasoning with items from the cognitive reflection test, ratio bias, a probability matching task, and base rate neglect items. We recruited over 500 participants from Norway and the Netherlands that had English as their second language. Participants were randomly assigned to either the native, switching or second language condition. We measured: number of correctly answered items–deliberate reasoning score, perceived effort, perceived accuracy or confidence, and language proficiency.

Deliberate reasoning was not increased when using a second language or when having to switch between native and second language. All three groups performed equally well. Significant predictors of deliberate reasoning were age, gender, education, perceived effort, and confidence but not the language context. Participants with low English proficiency spent more time reading compared to more fluent speakers.

There is no advantage of second language on deliberate reasoning in the absence of time pressure. Deliberation was not increased by providing items in a second language, but through the willingness to spend cognitive effort and time to read carefully.

Partial Text

Millions of people make decisions in a second language, and global trade and international agreements rely on second language proficiency. These decisions should be made carefully and wisely. However, human decision-making is prone to bias and systematic errors [1]. Is the use of a second language an advantage or a disadvantage for making rational decisions? That is, are we reasoning more deliberately when thinking in a second language?

The groups did not differ in their age, education, gender composition or language proficiency.

Our hypothesis was that a foreign language context or a language switching context would increase deliberate reasoning. We found no enhanced deliberation across different language contexts. This also applied after controlling for perceived effort. This is contrary to our prediction and the reduced intuition/increased deliberation account of decision-making in a foreign language. This agrees well with the previous finding from Costa et al. [5] study 4 using the three items from the CRT and the recent study [33] using three cognitive biases. Since Costa and colleagues compared native with second language it was still possible that language switching could enhance deliberation. However, our study found no enhanced logical reasoning in the switching condition either. Poor performance cannot explain the absence of the effect. Our participants had on average 11 out of the 16 items correct, and even when including solely the CRT items (N = 7) the average score was over 50% correct (see Table 1), whereas Costa et al. (2014a) found that only 17–34% had 2 or 3 items correct. Our data also questions whether switching is more demanding. We did not find higher perceived cognitive effort in the switching group than the native or second language group. This was contrary to our expectation but might be explained by our participants’ high second language proficiency [43]. There was a small positive correlation between perceived effort and deliberate reasoning.

There is a range of factors why deliberation was not affected by the language environment. Firstly, we tested persons that are comparatively well educated and that are proficient in English. Both in Norway and in the Netherlands, English is taught early in school and very prominent in daily life, e.g. movies are not dubbed. Secondly, using snowballing as the recruiting method could have biased us towards curious, open-minded participants, which are often also critical thinkers. Thirdly, a major difference to previous studies is our non-emotional material; and we also did not deceive participants but informed them that this is a study on problem-solving. This information could be sufficient to trigger attention and control mechanisms, needed for not answering intuitively. Indeed, participants less fluent in English did spend more time on a page before answering, indicating a motivation to do well in our tasks. As such, not the language context but knowing that we measure “thinking” may encourage participants to reason deliberately. Our results may differ if we would have applied time pressure. Intuitive responses are more prevalent under time pressure [10] and can lead to more honest behavior [56, 57].

Deliberate reasoning in a second language does not make us wiser. We found similar deliberate reasoning in one’s native and a second language, and the reasoning was perceived as similarly effortful. We know that willingness to spend cognitive effort depends on many factors [31, 43, 51, 58, 59] but the language context does neither increase nor hamper deliberation. This is reassuring for trade, because social efficiency is related to deliberation [17]. Still, our data cannot exclude the possibility that a small effect of language on deliberate reasoning exists. Furthermore, decision-making in a foreign language can still be beneficial for tasks with high emotional connotation [20, 27–30] and in moral judgments [3, 23, 24, 60, 61].




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