'Holiday' or 'Vacation': Similar language leads to more cooperation

In an experiment, 100 English-speaking study participants described pictures for two conversation partners. The pictures showed situations that the study participants could describe using two different grammatical constructions that meant the same thing. Descriptions such as "John gives Mary the book" or "John gives the book to Mary" were available to choose from. In a next step, the players' roles were switched and the study participants were confronted with picture descriptions of their partners. Finally, they had to decide which of their partners they wanted to co-operate with. The incentive for this decision was a subsequent game in which there was money to be won. "We found that, as expected, our study participants chose conversation partners who spoke similarly to them and used the same grammatical construction as them," explains Theresa Matzinger, first author of the study.

Group affiliation counts more than the willingness to adapt

In a further experiment, the research team disentangled what the reasons for the preference for linguistically similar conversation partners could be. The researchers had two hypotheses:

1. People prefer others who speak similarly because they might think that the others belong to the same social group, and one is more likely to cooperate with group members than with outsiders.
2. People favor others who speak similarly because they might think that the others are willing to adapt linguistically and might therefore also be more cooperative in other areas.

To test these two possibilities, the study participants had to name the pictures with the grammatical construction that sounded less natural to them. When they then had to choose their co-operation partners again, they opted for those who resembled their natural language use rather than those who resembled the language they used in the experiment.

"This clearly supports the first of our hypotheses: A sense of belonging to the same social group based on linguistic expression that are natural to oneself is the more decisive factor in the choice of cooperation partners. The idea that the other person is adapting to one's own way of expressing oneself and might therefore be more cooperative was much less important," says Matzinger.

Matzinger summarizes: "Our study shows that even small linguistic differences, which we may not even be consciously aware of, can play a role in our willingness to cooperate." The researchers hope that the results can subsequently be used to better understand how cooperative decisions are made in linguistically heterogeneous groups and to reduce prejudices against people who speak differently.