Social animals develop intimate bonds with their social partners. However, bond formation entails the risk of being exploited by partners. Previous studies have shown that people monitor partner attention to themselves to assess commitment to the relationship. Accordingly, a partner’s social attention promotes the receiver’s intimacy with the partner. This study expanded previous finding by manipulating partner attention in a naturalistic manner. In particular, naïve participants were assigned to one of two roles (i.e., signal Sender and Receiver) in the laboratory. Receiver first wrote a self-instruction essay, and Sender read it under either of two instructions: to pay close attention to the content of the essay (the high attention condition) or to some peripheral aspects of the essay (the low attention condition). After reading the essay, Sender’s memory of the essay was assessed. Naturally, Sender recalled it more accurately in the high attention condition. Knowing Sender’s accuracy, Receiver reported a sense of intimacy toward Sender. Receiver’s intimacy was higher in the high attention condition than in the low attention condition. Therefore, this study confirmed that paying attention to a partner, which translates to accurate understanding of the partner, promotes the intimacy in the partner.