Take a kitten and arrange its environment so it only sees vertical (or horizontal) stripes for the first few months of its life.
It has access to its mother, and food, even its siblings, but only with those available in pitch blackness.
It will just have a restricted visual experience of only seeing vertical stripes.
Do this to a kitten early in life and you get some dramatic results.
The kitten will be rendered blind to visual stimuli that are not vertical; there will be no behavioral response of perceiving any other visual stimuli except what it had been exposed to in training.
Such a kitten will attempt to play with stimuli that had been used in training but if raised in a vertical stripe environment no measurable response to visual stimuli in any horizontal planes can be measured.
But what about its brain? In the primary visual cortex, one would normally find “feature detector” cells with the peculiar habit of responding by firing to various basic visual stimuli. Some feature detectors respond with a burst of neural firing to lines and shadows with a vertical orientation, others to such stimuli but of an oblique orientation and so forth.
In our experimental cat, the only feature detectors that show neural responses will be those that respond to vertical stimuli. All the horizontal and oblique feature detectors have been “reprogrammed” for lack of a better word to now all only be horizontal feature detectors.
And the cat will never ever be able to see anything except vertical stripes.
The immature brain of the mostly glabrous primate known as Homo sapiens is very subject to environmental stimulation; the developing brain is said to have a high degree of plasticity such that it is very responsive to initial setting conditions that can have very enduring effects; brain plasticity is inversely related (for the most part) to age. The older we get, the less plastic (adaptable) is our brain.
So much for animal research you might say … but what about the human brain and early experience? Allow me some room to speculate.
The human brain is also very subject to initial setting conditions; individuals with congenital blindness have in some rare cases been “given” their vision after years of living and learning with a world as being blind.
These people have found the visual world to be a very confusing and they are in fact still blind to some visual stimuli. They cannot see depth or judge distance. Some individuals have attempted to step out of third or fourth story windows because they “saw” it was actually only a short distance to the ground.
Some such individuals preferred to cover their eyes or stay in darkness to not have to see stimuli that made no sense.
How long is the human brain sensitive to such life altering setting conditions? It’s difficult to say because the human brain is a work in progress. The formation of myelin occurs until we’re in our late teens.
Significance? What if we have only been exposed to one ideology or belief system for the vast majority of our youth?
Then if we are exposed to a diversity of ideas, totally alien to our prior experiences, who will actually see or seemingly be able to see? Would we only be able to see ideas that mesh with how our brains were programmed?
The good news is that human brains retain considerable potential plasticity, even into advanced age, given prolonged exposure to a diverse and stimulating environment.
But the key is prolonged exposure. If any person says “I have never heard such ideas, I don’t believe such ideas and I am not going to immerse myself in such ideas because I don’t want to believe such ideas…” Putting it bluntly, such a person is blind, will stay blind and will always be blind.
Brady Phelps is a behavior analyst in the SDSU Psychology Department. Comments on his Faculty Corner column may be sent directly to the Collegian at [email protected]