A profound concept, which I was recently reminded of by philosopher Paul Almond, serves as a follow-on to my previous post. The idea is that our perception of the real world is almost entirely constructed within our brains.
The language we use to describe the real world is misleading: it makes us think that the objects around us, and their meaning and function, are all directly understood simply by observing them. This is fallacious. What enters our eyes, for instance, are photons reflected off different objects in our surroundings. Our retina detects a patchwork of light and dark blobs of various colors. There is no meaning to be had at this stage. Only once the light has caused electrical signals to travel along our optic nerve to the visual cortex do we start to make sense of the data. Special parts of the brain are dedicated to the basic bread-and-butter of detecting objects in images, namely edge-detection, shape detection, distance detection, etc. Once these basic procedures are complete, other parts of the brain are responsible for assigning labels to the various objects, using our memory of previous sightings as a guide. “Ah”, our brain might be thought of as saying, “that is a spherical object with a patchwork of white and black shapes on its surface, and a particular size that lead me to conclude that it is a soccer ball, since that is what I have learned soccer balls look like.”
The same sort of data-to-semantics process occurs for the other senses too. Despite the astounding rapidity with which this process occurs, there are many steps involved. And at each step, the brain is susceptible to errors and false assumptions.
An analogy serves to demonstrate this idea further. We are used to thinking that our perception of the outside world is something like a person enjoying a view through her living room window. In reality, though, this person (our consciousness) does not stand before the window. Instead, she sits in the basement, and has information about the view outside her window sent down to her in the form of cryptic messages on little pieces of paper. In order for her to understand what is happening outside, she must collect these papers together in a particular order, and decode their messages. She often makes mistakes, and she frequently makes assumptions in order to save time.
This complex situation reminds us why good scientific investigations are usually so painstakingly thorough: our sensory flaws and interpretative prejudices must be properly eliminated before any conclusion can be trusted.