During the last decade, learning/teaching environment has assumed an important role in affect research due to the socio-constructivist account of learning/teaching mathematics. Despite this, the concept of interperson-al relationship, which is an important variable of the environment, has not yet been considered explicitly in affect research. The first aim of this paper is to show the importance of studying explicitly this concept in affect. The second aim is to underline a first characteristic of the interpersonal relationships. In the light of neuroscience results about mirror neurons, the authors observe that a relationship is characterized not only by the perceptible senses communication, but also by a hidden communication that takes place through mirror neurons sets and perhaps through other means not yet been discovered.