how our brains notice when something has changed?


For example, if I go into my room and something is moved, my brain will unconsciously realize and bring it into conscious awareness that something has changed. How does the brain detect these changes and decide it’s important enough to bring to awareness? What processes are happening when we notice changes?

In: 15

The brain runs a LOT of processes sub-consciously, that is, you are not even aware of them going unless some of them turn up something that the brain thinks should be brought to conscious attention. The brain has a mental picture of your room stored for reference, and when it sees something has changed, it will sound an alarm bringing this fact to consciousness, because it’s pretty important for safety reasons, obviously.

Your mind takes pictures for stock filler reasons. When we notice the small thing that is moved, it’s because we pick out the abnormalities in the routine we are used to seeing. There is a theory that touches this topic called ” The frog eye theory “

You can see your cerebral cortex as millions of little brains (organized like little columns, a bit like a honeycomb). Each little brain or cortical column is a model of part of your world. For example one cortical column could be a model of your school, or a model of your phone. This little column adds context to your experiences and fills in the gaps. It primes you to expect certain things in a certain situation.

When your experiences fit a model well, that cortical column is active and continually gets compared to your current experiences. Small differences get ignored and the model just gets updated. But when it clashes with something well established, like something important missing in your room, you get conscious of that difference.

I have an amateur interest in cognitive neuroscience, and I’m not a professional, so bear that in mind.

Both consciously and subconsciously, and over short and long time scales, your brain acquires “mental models” of the world and how it is expected to work. Models for things like how objects will behave if dropped (they will fall straight down until they hit something), how people will act in certain situations (they will get upset if you hit them), how things will feel if you touch them (sharp edges will cut you), etc.

Your brain takes the sensory input from eyes, ears, etc and combines it with these mental models to make predictions about what sensory input it might expect in the future. This happens continuously every waking moment and mostly without you even realizing it.

Your brain compares its past predictions with its current sensory input for differences, called prediction errors. If the error is large enough, our attention is drawn towards that input. Error indicates that something has changed and we may need to take action, or maybe just update our mental models to make more accurate predictions in the future.

This is why magic shows are so captivating. They are designed to cause large prediction errors by violating our mental models, and cause us to feel a sense of amazement and wonder “how did they do that!?”.

Psychosis in schizophrenia is hypothesized by some to be the result of a disruption in this process. If the brain erroneously decides a certain stimulus violates its mental models, it can be interpreted in odd ways and lead to their mental models becoming “corrupted.” E.g. A schizophrenic person observes the ordinary sight of two strangers talking in the park, falsely determines this has some special meaning relevant to him, and comes to believe that they are secretly talking about him.

Pattern recognition. Helped your ancestors notice the predator creeping in the tall grasses. They ran and lived. So now you notice when something is out of place.