social facilitation effect has been known since 1965 and means that people perform behaviors which are largely automated more easily in the presence of others. But the presence of others can be distracting when executing tasks which require much concentration (Horwitz & McCaffrey, 2008). In a new study Desender, Beurms, & Van den Bussche (2015) demonstrate that mental effort can be contagious.
In two experiments they had two pairs of participants (A and B) do a Simon task and they manipulated the difficulty of the task of only participant A. Making the task harder for A did not in any way affect the task of participant B because there was no need and opportunity for A and B to work cooperated at all. Their tasks were completely independent. Yet making A's task harder did not only make participant A put in more effort but also participant B. In experiment 1 the participant could see each other's task but in experiment 2 they couldn't. In experiment 2 the same effect was found.
Conclusion: mental effort can be contagious. Do you have to make a great mental effort? Seek the company of someone who is also making a great mental effort. I recognize the findings from this study. When I was working at home as a student I was easily distracted. When I was working in the library where many other students were studying I found it much easier to keep working, especially when I was sitting next to people who seemed to be working really hard.