The Brain Creates Models of the World

We make models in science, but we also make them in everyday life. Model-dependent realism applies not only to scientific models but also to the conscious and subconscious mental models we all create in order to interpret and understand the everyday world. There is no way to remove the observer—us—from our perception of the world, which is created through our sensory processing and through the way we think and reason. Our perception—and hence the observations upon which our theories are...

 Evolution of the Eye

A possible sequence of such changes begins with simple eyespots made of light-sensitive pigment, as seen in flatworms. The skin then folds in, forming a cup that protects the eyespot and allows it to better localize the light source. Limpets have eyes like this. In the chambered nautilus, we see a further narrowing of the cup’s opening to produce an improved image, and in ragworms the cup is capped by a protective transparent cover to protect the opening. In abalones, part of the fluid in t...

 What Makes Something a Distinct Object?

Let me look at the envelope from a very basic point of view, that of the neurophysiology of raw perception itself. Forgive me if it’s a bit oversimple. Take me-on the back of your retina I’m upside down, focused at the center but fuzzy at the edges, two-dimensional, a barrage of photons releasing rhodopsin and triggering neural impulses along the visual nerve. At the same time, the pressure wave I’m setting up right now with all this talk is causing little hairs inside the cochlea, in y...

 Evolution Versus Engineering

What's the difference between evolution and engineering? Engineering is the designing of a whole out of parts suited to their individual purposes. Evolution is the process of tiny incremental changes, each making some small or large improvement in the ability of the thing to survive and reproduce. A good engineer avoids the kluge-jargon for the use of a part not particularly suited to its purpose. But evolution favors, even cherishes, the kluge. Suddenly finding a new purpose for a part witho...

 The Idiotic Design of the Eye

Hermann von Helmholtz, the great nineteenthcentury German scientist (you could call him a physicist, but his contributions to biology and psychology were greater), said, of the eye: 'If an optician wanted to sell me an instrument which had all these defects, I should think myself quite justified in blaming his carelessness in the strongest terms, and giving him back his instrument.' One reason why the eye seems better than Helmholtz, the physicist, judged it to be is that the brain does an am...