Interesting topic - and experiment.
I think this goes along with the concept that you can say things in a sweet voice to a cat (or dog), and they will think you are being the nicest person in the world... even though you are cussin them out. Since they don't really understand some of the words - they have to go on the 'tone' of your voice.
So, you could be saying (said in a sing-song voice) "I'm gonna rip your little head off..." the cat will purr and think "How nice!"
(And no, I'm not condoning harming animals... it's just something I learned years ago - and do - when I am playing with my animals... especially when they refuse to come to me... and no, I don't literally 'rip' their heads off. I pet them. *grin*)
There's a gal where I work who is able to pull off the 'sing song voice' thing... I laugh at her, and say... "There's that 'go to he**', voice, again!" She laughs too. But, there is more truth there than many folks realize. She will use that voice in conversations with the boss lady, and she thinks the gal is being just the sweetest thing!
In general... even if the 'experiment' doesn't seem to be 100% successful, I'm sure that folks will realize an improvement in their general well-being and life.
But - you may want to also try to eliminate 'negative' influences like the news media... which only broadcasts 'negative' stories... or would this be going to far... and missing the goal or point of the experiment?