Don't believe in such a thing? well i have proof. The proof is performance figures between three shifts of operators on one production line. If this one person is in that shift production goes down by up to 15%. This has been a long term study over three months, we have found that if this one person is just in the production area, not even working on the line production output goes down. As i have said this was a long term study with all manner of people trying to identify the reason for the short fall, at no time was this person seen to be doing anything other than his job in a proper manner. This person was put on another production line, and yes output went down. The mechanical causes of reduced out put? well no mechanical failure, just a multiple of minor things that (could) happen any time. Now is that aint proof of a jink i give up.