In the study “participants’ friends, family and significant others were asked to write two letters: one unemotional letter (containing statements such as “you have brown hair”) and one letter expressing positive emotions for the participant (for example, “you are the only person who has ever cared for me more than yourself”). Subjects would then lie in an fMRI scanner while reading these letters from people they care about most.”
(Note visual translation below)
In brief, the positive emotional statements mattered.
A lot.
In a follow-up study, Matthew D. Lieberman and Elizabeth Castle found that: