I was agreeing with your posting Tony until I read the word "placebo"   This word is brought up far too readily in these discussions and used an erroneous answer to what isn't easily explained, especially when no objective evidence is to hand.  Look at the evidence that has been presented so far in this thread; more than one respondent has been able to summon the effect to command repeatedly and consistently.  This exact same effect has been noted by others introduced to it, again by command and more than once so the likelihood of a placebo effect being that contagious amongst so many subjects is virtually nil.  To the best of my own knowledge a true placebo has only been replicated, observed and recorded twice with one individual and that was in the absolute sense of the word. 

At least I can salute you for applying your mind in a positive manner to what it MIGHT be rather than the usual derisory ballyhoo that occurs from the more cynical quarters