One of those little things you notice
when life is basically constant
for a long time.
The kinesthetic perception system includes a fantastically complex library of per-object memories, containing at least weight and probably inertia and muscle settings for reach, grasp and release. A brand-new object has no expectations, so the hand proceeds experimentally, with guidance from the librarians based on similar-looking things. If the object has a constant weight within the time that you hold it, a memory is formed for the weight. If it's non-constant during hold (eg a coffeepot that gets poured out every time you pick it up) there's no expectation.
The next time you pick it up, even if several days later, you are unsurprised to find approximately the same weight. But if the weight is wrong, you NOTICE IT! SOMETHING IS OFF HERE! DELTA ALERT! DELTA ALERT!
Example: Salt container. Yesterday I noticed the existing container was nearly empty, so I bought a new one at Safeway. The new container looks exactly the same and weighs a pound more than the old one. When I picked it up just now, my hand was ready for the old 1-ounce empty, but found a full pound. SURPRISE! Nearly dropped it.
I don't know how extensive this library of weights is, but I'll bet it includes everything I handle more than once in the course of a year.
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Curbside Classic featured
an old magazine article on 1966 Rolls Royce technology.
Especially impressive: the fluidic analog computer that controls the suspension.
Height-sensitive devices at front and rear activate pumps in the hi-pressure hydraulic system which pumps fluid into the hydraulic rams between the top of the coil springs and their attachment to the body. Rolls added a separate system which adjusted the height immediately when the car was loaded or unloaded, but didn't alter ride height because of fast suspension movements on the road. They used one slow-response pump and one fast-response pump. The fast-response pump was enabled only when the door switch turned on the courtesy light, since the load changes rapidly when passengers and luggage are being loaded or unloaded. The slow-sensor pump responds to gradual changes in the car's weight, specifically the gradual decrease in the rear as fuel is used up.