In realizing that color is a perception created by own our neurons, it may be in our best interest to look at other behaviors this way as well. From the start I have tried to understand behavior as a very complicated phenomena that depends on reactions and interactions. But sometimes, behaviors come about as reponses to stimuli that don't exist.
Many people with behavioral "problems" perceive things that other people do not and then react improperly. An example of this kind of behavior is hallucinations which are also visual concoctions. Yet these fictions must also be considered behavior because the neurons create for some purpose or in reaction to some internal or external stimulus-- although we may not know from exactly what.
It is important to consider even these "deviant" types of behavior (or perception) as valid and important because we learn a lot about the functioning of the mind by taking a good account of these things. Knowing that color is a perception created by a reaction of the cones and ganglion to different wavelengths of visible light may eventually help us to understand what other kinds of stimuli can cause such puzzling stimuli as hallucinations. In a way we might already have a link because phantom limbs can be seen as a "created" perception via the touch neurons. Now that we can understand phantom limbs as a phenomena caused internally and not externally it is easier to understand that color perception is not unlike feeling a non-existent limb. The only difference is that color perception most definitely is created as a reaction to the external world (wavelengths of visible light).
Interesting and appropriate extensions. Yes, recognizing that the brain "makes up" color does encourage one to appreciate that different brains may interpret different things differently. And the phantom limb discussion helps one to appreciate that "making up" can occur either in reaction to an input or in the absence of inputs altogether. All of which tends to blur the border between "normal" and "abnormal" behavior. Clearly, if we're going to take all this seriously (and I think we should), we're going to have to deal with that problem. I'm not sure we can do a finished job in this course (in fact, I'm sure we can't), but its a good one to get a start on, so everyone can keep working on it. PG