LS: Speaking of Science Column April 12, 2009

Is it love or a case of crossed wires?

Imagine you have built a small robot car powered by two electric motors, one to each rear wheel. If the right motor revolves more rapidly than the left motor, the car will veer to the left.

If the left motor is faster than the right the car will turn right.

Imagine this car has two light sensors on the front, set several inches apart. These light sensors are connected to the motors of the car and control the power to the electric motors; the more light that hits the sensor, the faster the motor turns. The right sensor is connected to the right motor, and the left sensor is connected to the left motor.

Imagine we have placed this car in a darkened gymnasium. It will not move because there is no light. But we have placed a remote-controlled light bulb in the center of the floor. When we turn the light on, the car will begin to move.

However, because of the distance between the two sensors, the amount of light striking the right sensor will be greater than the amount striking the left sensor. This will cause the right motor to revolve faster and the car will veer away from the light until it is exactly facing away from the light so that the amount of light to each sensor is equal. It will also go as far away from the light as possible until the sensors are no longer stimulated.

Imagine you are observing this with a friend from the rafters of the gym. Your friend might say something like, “Wow, that thing really doesn’t like the light. It runs and hides. How did you make it do that?”

Of course, it doesn’t “like” or “dislike” anything. It’s a robot. It just appears to be a little like a cockroach.

Stay with me here. This is actually very applicable to you.

Imagine you make one small change in your robot; you connect the right sensor to the left motor and the left sensor to the right motor. Then you turn the light off, reposition your robot in the gym, and you resume your perch in the rafters.

When you turn on the light the robot moves, but this time it turns toward the light because the sensor on one side drives the motor on the opposite side.

Your friend says, “Oh look, it likes the light and is moving toward it.”

But wait, something is drastically wrong. As the robot gets closer and closer to the light, each sensor gets more light, and this makes each motor go faster. The robot hurtles directly at the light with increasing speed.

Your friend screams, “Look out! It’s attacking!” as the robot hurtles into the light, demolishing light and robot in one grand violent act.

“Wow!” Your friend observes after a stunned silence. “That robot really hates the light.”
Imagine you painstakingly reassemble your robot. This time you add one more tiny change: a governor on the light sensors so that it increases speed until a certain light intensity is reached. Above that intensity, the robot turns off the motor it is wired to.

Meanwhile, back in the gym, this time the robot turns toward the light and rushes toward it as before, but as it gets close it slows and stops and sits staring adoringly at the light bulb, never moving a motor.

Your friend observes, “Oh look, it’s in love with the light.”

What has this got to do with you and me? Maybe nothing. But cockroaches and most insects have brains that connect to the same side of the body (muscles as motors) as their sensors, whether those are eyes or antennae. You and I have crossed nervous systems. The left brain controls the right side of the body and vice versa. 

Does that partly explain human aggression? And is the difference between love and violence a simple breakdown of the speed governor, the braking system?

I don’t know. But if you think these ideas are intriguing, you would enjoy the book “Vehicles: Experiments in Synthetic Psychology” by Valentino Braitenberg, available from MIT Press and on Amazon.

Gary McCallister is professor of biology at Mesa State College and also owner/operator of Flaming Moth Productions and the “Bee bar Bee Ranch,” supplier of native bees, native bee nests and native bee information.

Got your wires crossed about a scientific topic? E-mail .(JavaScript must be enabled to view this email address).


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