Field note. The dwelling has a small illuminated node beside its entrance, positioned at the height of a resting hand. When a visiting human presses it, the structure emits a two-tone cry that penetrates every chamber within.
I observed the sequence eleven times. In each case the interior human, upon hearing the cry, ceased all activity, sat upright, and adopted a posture of alarm. This is notable. The node causes no harm. It announces only that another of their kind stands outside, wishing to be admitted. And yet the response is indistinguishable from a predator alert. Heart rate elevates. The human freezes. Some crawl below the level of the windows.
Then the sequence diverges by an unexplained variable. If the interior human is expecting the visitor, it moves toward the door with rapid, welcoming motion. If it is not expecting the visitor, it does the opposite: it holds absolutely still and pretends to be absent from its own dwelling, waiting for the exterior human to depart.
The same two-tone cry. Two opposite behaviors. The determining factor is invisible and appears to be entirely internal.
Preliminary conclusion: the humans have engineered a device to inform them that they are wanted, and have spent the greater part of their evolution learning to hide from it.