Social interactions such as mating and fighting are driven by internal emotional states. How can we study internal states of an animal when it cannot tell us its subjective feelings? Especially when the meaning of the animal’s behavior is not clear to us, can we understand the underlying internal states of the animal? In this talk, I will introduce our recent work in which we used male mounting behavior in mice as an example to understand the underlying internal state of the animals. In many animal species, males exhibit mounting behavior toward females as part of the mating behavior repertoire. Interestingly, males also frequently show mounting behavior toward other males of the same species. It is not clear what the underlying motivation is - whether it is reproductive in nature or something distinct. Through detailed analysis of video and audio recordings during social interactions, we found that while male-directed and female-directed mounting behaviors are motorically similar, they can be distinguished by both the presence of ultrasonic vocalization during female-directed mounting (reproductive mounting) and the display of aggression following male-directed mounting (aggressive mounting). Using optogenetics, we further identified genetically defined neural populations in the medial preoptic area (MPOA) that mediate reproductive mounting and the ventrolateral ventromedial hypothalamus (VMHvl) that mediate aggressive mounting. In vivo microendocsopic imaging in MPOA and VMHvl revealed distinct neural ensembles that mainly encode either a reproductive or an aggressive state during which male or female directed mounting occurs. Together, these findings demonstrate that internal states are represented in the hypothalamus and that motorically similar behaviors exhibited under different contexts may reflect distinct internal states.

What do other people really think of you? In this talk, I highlight the unique perspective that other people have on the most consequential aspects of our personalities—how we treat others, our best and worst qualities, and our moral character. First, I compare how people thought they behaved with how they actually behaved in everyday life (based on observer ratings of unobtrusive audio recordings; 217 people, 2,519 observations). I show that when people think they are being kind (vs. rude), others do not necessarily agree. This suggests that people may have blind spots about how well they are treating others in the moment. Next, I compare what 463 people thought their own best and worst traits were with what their friends thought about them. The results reveal that friends are more likely to point out flaws in the prosocial and moral domains (e.g., “inconsiderate”, “selfish”, “manipulative”) than are people themselves. Does this imply that others might want us to be more moral? To find out, I compare what targets (N = 800) want to change about their own personalities with what their close others (N = 958) want to change about them. The results show that people don’t particularly want to be more moral, and their close others don’t want them to be more moral, either. I conclude with future directions on honest feedback as a pathway to self-insight and, ultimately, self-improvement.