IUBio

Cross - Wired Eyes

Filip van den Bergh F.S.vandenBergh at students.fss.uu.nl
Tue May 15 03:40:16 EST 2001


Karl Self <karl.self at gmx.net> wrote in message
news:9dkgbm$j0icu$3 at ID-34153.news.dfncis.de...
> -  why is this so?

Well, I don't think anybody knows for sure, but there are some nice
hypotheses on that question. One explanation I've heard more than once (e.g.
Braitenberg: Vehicles) is that it's a matter of very early evolution.
Imagine a very simple organism that has only two sensory units and two motor
units. Now suppose those sensory units are wired to the motor units (like in
my very bad figure A, at the bottom of this post). That would mean that if
the sensors sensed something, the organism would move away from whatever the
sensory unit noticed. If the sensory units would be crossed (very bad figure
B), then the organism would move towards the distal source of excitation. I
suppose you'd say there is as much reason to move away from stuff (e.g.
predators or too much heat) as there is to move towards other stuff (food,
warmth). I think that's true, but I'd start with getting some food for my
very simple organism. Later, different (in this case uncrossed sensors)
could detect danger and avoid it.
It's but a theory (Braitenberg would call it an experiment in synthetic
psychology), but a very likeable one at that.

Filip van den Bergh

Badly drawn figures (best viewed in courier font)
S = sensory unit
M = motor unit
| = straight connection
X = crossed connection

Figure A

S1   S2
|     |
M1   M2


Figure B

S1   S2
   X
M1   M2






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