Every veteran of the World War will bear testimony to the fact that
wounds inflicted in the heat of battle frequently do not hurt; pain is
only experienced later on! A man may be wounded--even badly--and hardly
realize it for the time being. In his anger or excitement he does not
feel any pain or notice his injury. And we do not have to go to war for
proof of this. We have all of us scraped a finger, and drawn blood,
probably, without noticing it at the time. Only when our attention is
drawn to it later do we feel qualms, and perhaps pain! One is almost
reminded of “Alice Through the Looking-Glass,” when she observed the
White Queen scream first, bleed next and prick her finger last!
Yet even the slightest injury will cause us pain if our attention be
centered upon it at the time. A slight prick of a needle--enough to
draw one drop of blood--is keenly felt, if the mind is centered upon
that spot at the time. Why is it that the distraction of attention, and
particularly the arousing of strong emotions at the time, will prevent
or “inhibit” the sensation of pain?
The reason probably is that the nervous currents of the body, at such
times, are almost entirely “motor” currents--that is, nervous currents
which rush outwards from the central nervous system to the surface of
the body. Pain currents are incoming currents, and if there is no room
for them to get by, so to say, pain will not be experienced at the time.
It is like a railroad terminal, with an outgoing train on every track.
There is no room for incoming trains. The incoming trains are the
“pain” trains, which carry sensations. The outgoing trains correspond
to the motor nervous currents. That is why pain is not felt at such
times. As soon as the human tracks are cleared, and incoming nervous
currents can get through, pain is experienced for the first time.