My first job out of college was with a mosquito management company. In addition to taking blood samples from wild birds (tested for encephalitis etc.), we would set out chicken coops in the middle of woods and even in cities. We would let them get bitten by mosquitos and then take blood samples and test it. I can attest to the intelligence of chickens- not bright is an understatement. We would 'hypnotize' them by holding them by their feet and swinging them upside down for 15-20 seconds. This made getting blood samples much easier. I only did this for a summer but it took me about a year before I could eat chicken again.!
The way we do it is to hold the chicken for a while and pet it, so it's calm. Then you lay it on the floor (wood or cement is best) on it's side, and with your finger trace an imaginary line from the chicken's eye, away from them for a few feet. For some reason, they stare at the line your finger "drew" and they are zombie-like for about 30 minutes.
I do it to amuse City Kids who come out to the farm to buy eggs with their Moms. It's always a great hit, LOL!