How much of your brain’s activity are you actually aware of? Do you know everything that it’s up to, or are there some brain processes going on outside of awareness? You may be surprised to learn that some neuroscientists, such as Michael Gazzaniga, estimate that as much as 98 percent or more of all brain activity is completely unconscious.
This unconscious activity includes things like keeping your heart beating, digesting food, processing sensory input, controlling and coordinating muscle action, and much more. In addition to these sorts of “housekeeping” functions which promote the homeostasis of the body (and much more), there are probably a lot of higher functions—things that we would associate with thought and reasoning—which remain unconscious. At the very highest level of brain activity, there finally emerge thoughts that you can be aware of, that is, conscious thoughts. As you can see, these conscious thoughts represent just the tiniest sliver of the great mass of brain function.
Although we all have an experience of conscious thought, it’s been very difficult for neuroscientists to pin down the exact location in the brain that generates this experience. Conscious thought appears to arise in working memory, the system that allows the brain to hold temporary information and manipulate it to do tasks. Let’s say you want to add two numbers together; it is the working memory that allows you to hold both numbers in your consciousness, add them together, and behold the sum of the two. When you move on to another task, the working memory’s slate is wiped clean, and the process begins afresh.
According to the Baddeley and Hitch model, working memory contains special subsystems for phonological information (mainly the sound of language) and visual information (for picturing things in your mind’s eye), among others. As most of our thoughts are composed of words and pictures, it is likely that our ability to become aware of our own thinking is due to the function of these subsystems in working memory. What do you think of that?