i was going to make fun of you for saying "scientifical" but turns out, it's a real word PPPP
to answer your question, "scientifically", i think it's because when you speak from the heart (as you put it) you automatically give off a positive vibe. people can see and sense that you aren't just some fake, you are truly being yourself. others will find people like that to be attractive and will want to talk to them more because the fact that the other person is positive makes the person that they're talking to also feel positive, and it makes them feel good about themselves
just think of someone fake or negative...would you want to talk to that person? i'm sure they wouldn't make you feel good about yourself because their actions and the things they say would bring you down and create negative feelings in you as well