For at least two reasons the likelihood of smart mechanisms in perception should be considerable. ...This second line of reasoning seems simplistic to me. Grant that when humans design things they often try to make them no more complex than necessary. But, humans often design things starting from a "clean slate". By contrast, when natural selection designs things it must begin with "what its got". So, when natural selection began to design bipedal walkers, it had to begin with a spine that was originally designed for quadrupedal locomotion. That means that there can end up being an ultimate design that is suboptimal. By parity of reasoning, for all we know, natural selection faces certain design constraints when it begins to develop visual systems using things like light-sensitive cells. It seems to me that it is our ignorance of possible design constraints that makes this kind of evolutionary speculation fraught with risk. This is why this does not seem all that convincing to me.
The second reason has to do with the principle that when designing something one does not normally make it more complex than necessary. The perceptual mechanisms were not designed by a human mind, however, and are therefore not subordinate to the same complexity scale(s) as man-made devices. Biological evolution might have arrived quite easily at solutions which require the utmost of capacity and sophistication of a human mind for their basic principles of operation to be understood. (Runeson, 1977, p. 174).
And I am willing to grant the possibility of what biological evolution might have done, but recall that at this point Runeson is supposed to be arguing about what biological evolution has likely done, or at least why "the likelihood of smart mechanisms in perception should be considerable." (I'm assuming that "considerable" means something like high, but I guess it could mean non-negligible. Kind of unclear really, if you ask me.)
Runeson, S. (1977). "On the Possibility of 'Smart' Mechanisms" Scandinavian Journal of Psychology, 18, 172-9.