It is not really about better cooperation
Researchers at Cornell University focused on firefighters, who cook and eat together during their long shifts. Cooking together was definitely linked to higher group performance; in contrast, merely sharing the same table and eating together had no impact. Therefore, better negotiation outcomes when sharing a meal are probably not based on fostered cooperation, according to an article on the INSEAD business school website.
In another study from the US, researchers conducted experiments with competitive and cooperative negotiations. There was food sharing and also straightforward food consumption with no sharing.
Competitive negotiations
The negotiations in question were merger deals. In this instance, food sharing produced the best negotiation outcomes. So if your counterpart has a competitive reputation or you face a conflict or impasse, it may be a good idea to negotiate over a shared meal with dishes that make it possible for everyone to serve themselves: for example, Spanish tapas or Asian dishes. Food sharing in competitive settings makes parties negotiate with the value creation goal in mind.
Cooperative scenarios
Negotiators who shared food reported inferior value deals compared to competitive or control groups without food sharing. So if your negotiation is already expected to be cooperative, food sharing may reduce your awareness and alertness, leading to deals of lower value. If you are in a cooperative environment from the outset, you should give preference to each individual ordering their meal separately.
In order to maximise value creation, you should think carefully about sharing a meal, based on the situation.
-jk-