‘Friendships start better with a smile – Being aware of positive emotions may help to form, maintain relationships’, http://www.springer.com/gp/about-springer/media/springer-select/friendships-start-better-with-a-smile/293828, Motivation and Emotion, Springer (26 May 2015).
Campos, B. et al (2015). Attuned to the positive? Awareness and responsiveness to others’ positive emotion experience and display, Motivation and Emotion. DOI 10.1007/s11031-015-9494-x
People are much more aware of others’ positive emotions than their negative ones. (…) When finding themselves in situations where new relationships can be formed, humans tune into the positive almost instinctively. (…) Findings provide new evidence of the significance of positive emotions in social settings and highlight the role that positive emotions display in the development of new social connections.