I think it may all be about mindset. I have been on plenty of investigations where you can see people all start off happy and extrovert with body language, but soon become tense and flinch at the slightest cold breeze. The cold breeze was always there - they just weren't receptive to it. So if you start off watching paranormal shows on TV you can turn your senses ON or, of there is anything present it may realise you are listening and try and interact. Interesting about the possessed guy and the effects it had on the interviewers. I wonder what was going on there?