One of the things I have yet to really think through and discuss is how chickens may be able to evolve emotionally, much as humans do, and I believe this emotional development is aided by this interesting hormone, mesotocin in birds and oxytocin in humans.
The example of this in my own flock is a hen seeing an opportunity for emotional closeness when I am engaged in the simple task of scooping poop in the run. The hen herself initiates this, and I have several who do this, coming up close and raking her foot across the sand or across my knee as a signal to be picked up and held closely.
The more closely the hen is held, the more blissful is the reaction. And even the most active and motion-driven chicken will show no anxiousness to be released, content to be held in this close snuggle for as long as I'm willing to devote the time and energy to it.