What factors govern the intelligence of humans and other animals? One theory claims that it is not merely the size of the brain but also the number of inputs - the number of perceptions. Add an extra sensory organ linked to the brain and the brain will create new areas of sensory perception. Similarly, take away one of the senses and that part of the brain will shrivel in significance and possibly be assigned other tasks. This isn't the place to argue about IQ tests and, having taken a few, I think there are some good ones and some poor ones. I feel that intelligence is correlated to the ability to create connections, especially new connections. Memory may help in this but in itself is merely the ability to recall information rather than processing it. Anyway, what's all this got to do with eyes?
Paul Pietsch and Carl Schneider ran some interesting experiments to test the above theory using salamanders and their eyes. You can read Pietsch's own amusing description of the experiments at his website. The idea was to add a third eye to embryonic salamanders and link it to their brain so that it would (hopefully) become functional as the creatures grew. To test all the different scenarios they developed a number of 'hybrids'. The Triclops was the main subject, with two normal eyes plus a third one in its forehead - pretty much where humans have their 'third eye' just in front of the pineal gland. A Cyclops was also created with the third eye but without its two normal eyes, as was a one-eyed version with just one normal eye but without the third one. One normal subject was also used as the base level reactions as well as one totally blind so as to remove effects from light sensations that are non-visual such as heat.
The experiment itself involved using a light source and training the salamanders to avoid the light with small shocks applied then measuring how long this Pavlovian training took to be mastered. The ability to learn was thus taken as a sign of intelligence. Using the normal salamander as the control they translated their data into a numerical value using the IQ scale, thereby fixing the normal creature at 100. Pietsch and Schneider must have felt pretty smug with themselves; the Triclops, with the third eye, achieved an IQ of 117, whereas the one-eyed salamander came in at 80. On the surface it looked as if the theory linking intelligence to sensory inputs was validated. The removal and addition of one eye seemed to correlate strongly with a difference of about 20 points. However, the scientists had one huge shock to contend with - the Cyclops, the salamander with just one central eye, had achieved an IQ of 173!
The salamander with just one eye - and that eye not even being one of its normal ones - had come top of the class. It wasn't a question about whether three eyes were better than two; it seemed like one 'third eye' was the best of the lot! This needed some serious rethinking.
To cut to the chase, it looks as if the brain not only processes our senses but also mediates them. To live in reaction to raw data is to live in permanent over-stimulation. The difference here is between optimum perception and maximum - they are not necessarily the same. I think it would have been interesting if Pietsch and Schneider had continued their experiments to see if the Cyclops would grow to develop its own mental editor, thereby sacrificing its 'raw intelligence' for a more subtle, more adaptive - and yes, perhaps slower - mode of response.
For humans, this mediation of sensory inputs has both positive and negative consequences. The brain tries to filter out what it perceives as unimportant and yet by doing so may miss critical information. Sometimes we need to clear out this mass of feedback mechanisms and return to the raw source. That doesn't mean that we can live in a world bombarded by sensory inputs, but sometimes it is worth flushing out this mental cache so that we can see the world, and ourselves, in a more revealing light.