Well, aside from my peers - who accepted it with very little proof (I had unusual credibility, and I think I could have told them I was an alien-baboon hybrid and they'd have believed me

) - the first adult to take notice of my 'abilities' was our school psychologist, who I was seeing ostensibly for 'speech therapy'. She, at first, dismissed it as childish imagination; but on a particulary good day (and I have no idea what made this ability stronger or weaker) I was able, over the course of an hour, to tell her whether an adult or a child was about to pass her single office window, by pointing directly to where I saw/felt the aura moving. I'd point at roughly where I sensed the head and declare, "kid" or "adult", and when they passed the window, I was right - every single time.
(This was a school comprised of trailers, so there was a bit of traffic past her window, even during class time.)
Incidentally, this was one of the ONLY times I was able to sense an aura through walls - normally, I had to have line-of-sight, and on bad days, heavy clothing or coats could interfere with the ability.
Anyway, after I was able to make that demonstration, she referred me to specialists (I have no idea who they were with, anymore; all I can remember now is lab coats and sterile rooms) who came to the conclusion that I was suffering major chemical imbalance from puberty combined with metabolic problems from ADHD, that was causing a 'perceptual shift' letting me 'see' body heat. The problem with that theory, was that I could use it to recognize specific familiar individuals, to recognize moods and general health (just towards the last months I had this 'gift'), and that no amount of 'chemical imbalance' is going to so radically alter the structure of your optics to allow you such major vision changes without probably blinding you in the process.
Honestly, I think they were just fishing for an explanation that didn't involve having to admit something weird was going on.
Not long after that particular battery of tests, my parents decided I'd had enough, and ordered the school and the doctors to leave me be; they shortly thereafter moved to another city, and I only had a year or two left before puberty finished with me to enjoy this 'aural sense'. (The girls thought I was a sweet, sensitive guy.)
The only strange thing with my vision now - other than a peripheral field of about 5 extra degrees on each side - is that I can't tell two close shades apart - especially dark shades - and I tend to be more 'empathic' than most people - I can quickly 'sense' what mood people are in without trying. I can only assume (from a skeptical standpoint) that there is some signal - maybe pheremonal or something? - that I pick up on and have learned to read without being aware of it. Though, ironically, when it comes to social situations and body language - CLUELESS. I had a girl hit on me for YEARS, and I never knew it. Apparently all my friends knew, and decided it was funny watching me COMPLETELY MISS the signals... Ah, well.
I've done what research into this that I could, and I frankly have no proper explanation for what happened to me. The 'chemical imbalance' thing doesn't cut it, and I know I wasn't deluded - but, by everything I can find, there should have been no way for me to do what I did. I'm one of the most skeptic people now when I encounter 'aura readers' precisely because I remember what it was really like. For example, there's no such thing as 'common aural colors' - no two people share the same pattern, nor the same 'colors' for moods or health. There are similarities, but invariably, each person I dealt with had one or two moods or situations where what I 'sensed' was vastly different from their peers. And the ability waxes and wanes for reasons I don't know, sometimes spontaneously coming into major focus, other times barely existing as a flicker, and of course, going out altogether, with no rhyme or reason.
Now, as to your initial experiment - there ARE types of dummies that could be set up to 'breathe' and 'twitch', perhaps through some sort of remote puppeteering - but you'd be getting into an expensive test. You could also put the dummies and person into a dark room - my experience was that auras were unaffected by ambient light (which really spooked out my friends - they thought I had killer night vision at first, until I fell over the coffee table three times. All I could see were them - and the dog). You could also permit them only a quick glimpse somehow - just brief enough to catch an aura, but not long enough to pick up on breathing or movements. There's no 'tuning in' to auras - you either see them or you don't. Well, whatever it was I was seeing was like that - you either saw it, or you didn't. Just a second's glimpse would be enough to spot an aura instead of a dummy.
Of course, this will drive most 'aura readers' away instantly, I think - I really doubt there are many adults at all that have whatever it is I had as a kid. And as I expressed before, most kids with it are either keeping their mouths shut, not being believed, or don't know about tests like this anyway.