Task performance can be influenced by the mere presence of another person. In previous work, it has been shown that this depends on what this other person is doing. More specifically, it has been observed that the degree of cognitive control one person exerts during a task affects the amount of cognitive control exerted by another person. This has led to the conclusion that cognitive control is contagious. As this is a bold claim, the current study aims to replicate these results by using a task requiring a higher degree of cognitive control and additionally explores the influence of interpersonal relationships on this effect. In our study, two participants (A and B) are seated next to each other while individually performing a Simon task on their side of the screen. While task difficulty of participant B remains neutral throughout the experiment, participant A either receives an easy task requiring little cognitive control or a difficult task requiring more cognitive control. In line with previous work, we expect that the task performance of participant B will be modulated by the task difficulty of participant A. Furthermore, we hypothesize that this effect is stronger when people have a stronger interpersonal relationship.