Robert Krulwich has a fascinating piece on NPR about the binding problem and the speed of nerve transmission. In essence, it takes a split-second longer for sensory signals to reach the brains of tall people, which means that their “now” is actually a little less timely. (This explains a lot about the NBA…)
Because for the taller person it takes a tenth of a second longer for the toe-touch to travel up the foot, the ankle, the calf, the thigh, the backbone to the brain, the brain waits that extra beat to announce a “NOW!” That tall person will live his sensory life on a teeny delay (at least as regards toe-touching). This, of course, could apply to all kinds of lower-extremity experiences — cold or heat against the skin, tickles, rubs, hitting a soccer ball — the list goes on and on.
The larger issue here is the “binding problem”. At any given moment, billions of neurons all over the brain are lighting up, reflecting the hodgepodge of sensations simultaneously activating our sensory cells. Perhaps we have an itch on our thigh, and we’re smelling a fresh pot of coffee, and we’re looking at the pixels on a computer screen. We’re also listening to the whoosh of the air-conditioner (and the distant hum of highway traffic) and just noticed that we’re getting hungry.
The problem, of course, is how all those discrete perceptions (represented by distinct patterns of cellular activity) get bound together into a single moment of experience. The neuroscientist David Eagleman, however, proposes that the brain solves the problem by patiently waiting:
It may be that if the brain wants to get events correct timewise, it may have only one choice: wait for the slowest information to arrive. To accomplish this, [the brain] must wait about a tenth of a second. In the early days of television broadcasting, engineers worried about the problem of keeping audio and video signals synchronized. Then they accidentally discovered that they had around a hundred milliseconds of slop, and as long as the signals arrived within this window, viewers’ brains would automatically resynchronize the signals.
What does this have to do with tall people? Because it takes a few extra milliseconds for the far-away body signals of a tall person to reach their head, his or her brain must wait a little bit longer. The end result is that the moment of binding – that fleeting neural representation of now – is late.