Here's how I explained it to my dad when he expressed some cynicism at the idea that my Grandfather could be described as "sensititve" :
It doesn't mean necessarily personal sensitivity in terms of empathy or "feelings," (but that can be one part of how it manifests depending upon whether the personality develops to tune that specific signal type in or out in order to manage it better).
From what I gathered of the science part: Its the predisposition or tendency towards "overexcitablity" due to heightened reaction on a physiological level to stimuli in general - for example: finding the noise and chaos of large crowds uncomfortable or being more easily disturbed by incessant ringing of the telephone or dogs barking or finding things overwhelming when things are not within their control. Personally I have always had a particular dislike for things like shopping at large warehouse stores like Costco or crowded supermarkets like Fedco with Mom as a kid. And very little tolerance for audio irritants in particular; helicopters that circle for longer than a minute or so, high-pitched electrical whine or constant but inconsistent buzzing of flourescent lighting, the noise of someone vaccuuming, or even "white noise" from a filter or fan can make me downright irascible if it goes on too long or I get tired of trying to tune it out, even when no one else is around.
To me, such a thing makes an otherwise relaxing and calm environment feel uncomfortably "busy." I feel actual relief when I turn off an air-conditioner or noisy appliance where most people wouldn't have noticed a difference it the atmosphere at all. When I built my computer "RoarCore" (so dubbed for the Leo aesthetic scheme), I used silicone bumpers between the case and the fans and each screw to cut down on the vibration noise because it actually makes me so tense. RC is notably quieter than my VAIO despite having at least 4 or 5 addtional fans in the case. (Much more pleasant to use for the simple reason that I can hear people talking to me while its on.)
Its the predisposition to become overwhelmed in that manner which is apparently genetically part of the central nervous system wiring. I sort of imagine you could liken it to buying a stereo head unit: most require an external additional amp to get a higher quality sound output, whereas some units might contain a booster inherent in the original hardware - like a signal pre-amplifier - that can wire direct to the speakers without requiring the additional external signal amplification or separate power source. Instead of amplifying sound output, the gene instead serves an amplifier for any stimuli that is input. Supposedly, you could measure this by brain wave reaction (or like a lie detector which measures the physiological responses by electrical current) and see that any stimuli, such as ambient noise level, or exposure to graphically violent images would result in a higher frequency or level of activity in HSP's nervous system when compared with those non-HSP reactions to the exact same stimuli. In order to match the same nerve signal output in non-HSP's, you would have to "crank up the volume" on the noise or increase the gore factor in the images they were exposed to by significant margin.
Even from the little that has been said about her being extraordinarily smart but "a little crazy" (o maybe it was "them" - can't remember if he had one or two) I was actually thinking about Grandad's sister(s) when first presented with the idea of HSP genetics. Or possibly Popo. The tendency is for the majority of HSP's to be introverts (many who work in research and technology fields that are somewhat solitary, LOTS of programmers, IT people it seemed at the meeting) which would fit Grandad pretty well also. The speaker at the meetup described how HSP family members would "often prefer to remain scarce during Holiday festivities or family gatherings, only showing up for a brief time before retiring to whatever solitary space they were accustomed to" - that one sound familiar? I thought it was a little weird that something that specific could be called out like that. And think too about how concerned he was that his work was of some value to the whole of humanity rather than just himself or personal wealth. Might make more sense after reading a little more of the articles...
FYI - on the 10 question "empath" quiz, I scored 100% and onthe standard (and more traditionally accepted academically) 27 question survey to indicate HSP, I scored a comfortable 22 positives (14 qualifies as a strong indicator.) My Myers-Briggs is usually ENFP though those designations are FAR more borderline than this grouping.
He replied back with this:
As is said in Japanese, na-ru-ho-do, I see.
Spot on about his two sisters, Lula and Mary, and the
line about the gatherings is as accurate as a photograph.
I'm fascinated. Got some reading to do.
Remember Aiko - the woman who I brought to meet
you a couple of years ago at karaoke??
From all of what you have sent, I would say that
she, too, is an HSP. The part about the noises
is just one of the descriptions specific to her.
I'll keep reading.
Love,
Dad
