“Vehicle I is equipped with one sensor and one motor (figure I). The connection is a very simple one. The more there is of the quality to which the sensor is tuned, the faster the motor goes.”
pg 3
“As the vehicle pushes forward against frictional forces, it will deviate from its course. In the long run it will be seen to move in a complicated trajectory, curving one way or the other without apparent good reason. If it is very small, its motion will be quite erratic, similar to “Brownian motion,” only with a certain drive added.
Imagine, now, what you would think if you saw such a vehicle swimming around in a pond. It is restless, you would say, and does not like warm water. But it is quite stupid, since it is not able to turn back to the nice cold spot it overshot in its restlessness. Anyway, you would say, it is ALIVE, since you have never seen a particle of dead matter move around quite like that.”
pg 5
“Vehicle 2 is generally similar to Vehicle I except that it
has two sensors, one on each side, and two motors, right and left
(figure 2). You may think of it as being a descendant of Vehicle I
Of course you notice right away that we can make three kinds of such vehicles, depending on whether we connect (a) each sensor to the motor on the same side, (b) each sensor to the motor on the opposite side, or (c) both sensors to both motors. We can immediately dismiss case (c), for this is nothing but a somewhat more luxurious version of Vehicle 1. The difference between (a) and (b), however, is very interesting.
Consider (a) first. This vehicle will spend more time in the places where there is less of the stuff that excites its sensors and will speed up when it is exposed to higher concentrations. If the source of the stuff (say, light in the case of light sensors) is directly ahead, the vehicle may hit the source unless it is deflected from its course. If the source is to one side (figure 3), one of the.sensors, the one nearer to the source, is excited more than the other. The corresponding motor will work harder. And as a consequence the vehicle will turn away from the source.
Now let us try the other scheme of sensory-motor connections, (b) in figure 3· No change if the source is straight ahead. If it is to one side, however, we notice a difference with respect to Vehicle 2a. Vehicle 2b will turn toward the source and eventually hit it. There is no escaping: as long as 2b stays in the vicinity of the source, no matter how it stumbles and hesitates, it will hit the source frontally in the end.”
“Let Vehicles 2a and 2b move around in their world for a while and watch them. Their characters are quite opposite. Both DISLIKE sources. But 2a becomes restless in their vicinity and tends to avoid them, escaping until it safely reaches a place where the influence of the source is scarcely felt. Vehicle 2a is a COWARD, you would say. Not so Vehicle 2b. It, too, is excited by the presence of sources, but resolutely turns toward them and hits them with high velocity, as if it wanted to destroy them. Vehicle 2b is AGGRESSIVE, obviously.”
pg 9
“What comes to mind is to introduce some inhibition in the connections between the sensors and the motors, switching the sign of the influence from positive to negative. This will let the motor slow down when the corresponding sensor is activated. Again we can make two variants, one with straight and one with crossed connections (figure 4). Both will slow down in the presence of a strong stimulus and race where the stimulus is weak. They will therefore spend more time in the vicinity of the source
than away fro_m it. They will actually come to rest in the immediate vicinity of the source.
But here we notice a difference between the vehicle with straight connections and the one with crossed connections. Approaching
the source, the first (figure 4a) will orient toward it, since on an oblique course the sensor nearer to the source will slow down the motor on the same side, producing a turn. toward that side. The vehicle with straight connections will come to rest facing the source. The vehicle with crossed connections (figure 4b) for analogous reasons will come to rest facing away from the source and may not stay there very long, since a slight perturbation could cause it to drift away from the source. This would lessen the source’s
inhibitory influence, causing the vehicle to speed up more and more
as it gets away.
You will have no difficulty giving names to this sort of behavior. These vehicles LIKE the source, you will say, but in different ways. Vehicle 3a LOVES it in a permanent way, staying close by in quiet admiration from the time it spots the source to all future time. Vehicle 3b, on the other hand, is an EXPLORER. It likes the nearby source all right, but keeps an eye open for other, perhaps stronger sources, which it will sail to, given a chance, in order to find a more permanent and gratifying appeasement.”
pg 10