By Christian Jarrett

Mental imagery helps us anticipate the future, and vivid mental pictures inject emotion into our thought processes. If operating in a foreign language diminishes our imagination – as reported by a pair of psychologists at the University of Chicago in the journal Cognition – this could affect the emotionality of our thoughts, and our ability to visualise future scenarios, thus helping to explain previous findings showing that bilinguals using their second language make more utilitarian moral judgments, are less prone to cognitive bias and superstition, and are less concerned by risks.

Sayuri Hayakawa and Boaz Keysar began by instructing 359 online participants, all native English speakers who were also fluent in Spanish, to mentally simulate 35 different sensory experiences, such as imagining the feeling of sand, the taste of salt, or the sight of the sun sinking below the horizon. After imagining each experience, the participants rated how vivid it was. Critically, half the participants performed the challenge in English, while for the others, all the instructions were in Spanish.

Overall, the participants who completed the mental simulations in their second language, Spanish, reported that their mental images were less vivid. This was true for six out of the eight sensory categories tested. The exceptions were for gustatory and olfactory images (in fact, the latter were more vivid in Spanish than English, perhaps, the researchers speculated, because of the rich connotations of Spanish cuisine).

You are probably thinking that there are many possible explanations for why participants might self-report their mental images as being less vivid in a second tongue and that this isn’t a convincing finding. To obtain a more objective measure, Hayakawa and Keysar conducted a second experiment with 307 more participants, all native Mandarin speakers who were also fluent in English, that involved them completing a word test that depended on visualisation for accurate answering. For example, a typical item asked the participants to look at the words “carrot”, “mushroom” and “pen” and say which shape is the most different. Half the participants completed this test in their native Mandarin, the others in English.

The participants who completed this task in English, their second language, performed less accurately, suggesting they had found it more difficult to visualise the different shapes. You might wonder if this was just an effect of vocabulary competence rather than mental imagery, but the researchers checked for this possibility in two ways.

They had the participants repeat the test with pictures rather than words (so therefore not requiring visualisation). They also asked the participants to complete a similar test that required them to identify the odd one out based on word meaning, with no need for visualisation (for example, identifying the category which is most different from “carrot”, “mushroom” and “pen”). The results were clear: the participants’ accuracy was poorest of all when using their second language to perform the test that required visualisation.

These new findings don’t tell us why mental imagery is diminished in a foreign language, although the researchers’ favoured explanation is that when we use our imagination we often draw on past experiences that likely occurred in our native tongue. Imagining in a foreign language may therefore impede the ability to use these memories effectively (consistent with this, it’s known that imagination uses brain areas that overlap with autobiographical memory).

The researchers used a final experiment to test the idea that diminished mental imagery might explain, at least partly, why we make more utilitarian judgments in a second language. For this they asked 800 native German speakers, also fluent in English, to complete the famous Trolley thought experiment, either in their native tongue or in English. This moral dilemma asks whether you would sacrifice one large man – by pushing him off a bridge to stop a speeding trolley – to save the lives of five people who would otherwise be crushed to death by the trolley.

Once again, half the participants read and answered the Trolley dilemma in their native German, the others in English. Additionally, all the participants stated how vivid different aspects of the dilemma were in their minds, including the large man, the would-be victims and the scene overall. Replicating earlier research, the participants who took part in English, their second language, made more utilitarian judgments, in that more of them were willing to sacrifice the large man for the five would-be victims. Importantly, this difference was explained partly by the fact that those taking part in English said that their mental picture of the large man was less vivid than those participating in German. Presumably, when your image of the man is less real, it is easier to contemplate shoving him off the bridge.

“Over the last few years, there has been growing evidence that the use of a foreign language affects many aspects of our experiences ranging from emotional responding to decision-making,” Hayakawa and Keysar concluded. “Here we provide some evidence that such phenomena may occur because the world imagined through a foreign language is less vivid than through a native tongue.”

It is fascinating to wonder how these effects might play out in the real world, particularly in international politics. Just this week it was reported that Sir Nick Clegg, former deputy Prime Minister of the UK and a leading Remain advocate, said he had encountered a “barely concealed, almost sneering disregard for the politics of identity and the politics of patriotism” among EU officials. English is the main language used by EU civil servants, meaning that many EU officials are operating in a second language, potentially influencing their thoughts to be less vivid, less emotional and more utilitarian. “The genesis of European integration was to go above and beyond the trap of patriotic politics,” Clegg continued. “But it was a terrible misreading of what makes people tick. We are all tribal people.” It is speculative to say, of course, but perhaps it is easier for European bureaucrats to reject such tribal instincts when they are thinking and interacting in their non-native tongue.

—Using a foreign language reduces mental imagery

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest