Mo'at's Blood Test

[Raptor]

I've always wondered. How does Mo'at know that Jake is sincere by simply sampling his blood? Does a Na'vi's blood content somehow change when someone is in different states of emotions? Does Jake's body and facial language give it away, thus allowing Mo'at to induce his intentions? Is Mo'at somehow spiritually connected to everyone including Jake, and thus took faith in him because of Eywa? Or did she take a gamble on Jake?

James Cameron mentioned that animals on Pandora have heightened instincts, but are certainly not telepathically connected. Thus, Mo'at's reasons to let Jake stay has never been too clear to me.