Japan makes a rat robot specializing in making other rats depressed.
spectrum.ieee.org
spectrum.ieee.org
Seriously, though, this is something I continue to resent about much of the contemporary dialog around bullying: It fails to acknowledge and address the point that bullying works -- or it has in many traditional social and societal contexts. That's why/how it continues to exist.
If researchers can use it to reliably induce depression -- albeit in rats -- that's really something to think about.