Our taste buds are overly sensitive to and prefer salt, fat, and sugar for evolutionary reasons: during most of our existence as a species, these items were hard to find in the available diet, so we developed extra reward for seeking them out. Now these items are easily available, we eat too much of them, and our health suffers.

Is there a similar evolutionary argument for contrast/saturation/sharpness in vision? Do we prefer these for some reason tied to survival early in our history? Is there advantage to seeing color vividly? Galen Rowell, in Mountain Light, wrote a message to photographers written from the point of view of a roll of film: “The vision through your eyes is filtered through your brain, which interprets colors for you before you ‘see’ them. Humans must have had an evolutionary need to see colors in relation to one another no matter what the lighting source. Now you have a visual ‘appendix’ left over from a time when your ancestors needed to recognize the tawny coat of a Pleistocene lion on the African savannah by moonlight, at dawn, or by the light of the noonday sun.”

Neuroscientist Beau Lotto’s TED talk at about the 2 minute mark has an impressive demonstration of this.

So perhaps sensitivity to saturation helped us to better distinguish the color of ripe fruit and sharpness/contrast helped us to spot that predator in the bushes before it was too late. But what is “wrong” or maladaptive about contrast/saturation/sharpness? There seem to be no obvious health implications to excess contrast/saturation/sharpness as there are with salt, fat, and sugar.

But perhaps there are some subtle ones.

While there is a lot of concern about the effects sensory over-stimulation in the development of children, the effects on mature adults are not as widely discussed outside of what excess salt, fat, and sugar do to our taste buds. Signals from our taste buds trigger the dopamine reward system in our brains. Overloading this system decreases our sensitivity to dopamine and more salt, fat, and sugar are needed to produce the same level of pleasure or satisfaction. This is the road to addiction.

I have not found any indication so far on whether visual stimuli also tie into the reward system, but we can look for clues. For example, can we see signs of an escalating need for stimulation in photography?

Maybe. Today it is no longer enough to enjoy a photograph of a beautiful moon. It has to be a “super blue blood moon” to get our attention. We’ll probably add a new adjective every year. The Milky Way has to be accompanied by artificially-lit objects in the landscape, and the more the merrier.

The words we choose may offer another clue. For example, today every shot is “stunning,” yet we never see people stumbling dazed and confused or strewn on the ground passed out after seeing a “stunning” photo.

In early 2019, astronomers released a breakthrough image of the event horizon of a black hole. Some critics panned it as not very striking. They missed the point. This image wasn’t released as a visual delight. It represents expanding horizons in science and imaging technology. It seems we have salt, sugar and fat to stimulate our taste buds, perhaps contrast, saturation, and sharpness to stimulate our “eye buds”, but no “mind buds” to be stimulated by extending our knowledge.

None of these clues is definitive evidence for physiological harm from visual over-stimulation. In fact, my feeling is that they are instead examples of a pervasive problem today, that people too easily mistake external stimulation for significance. But that perhaps, is a topic for a future article.