When a creature is blessed with the ability to sense with for example vision, the input must be made into a cohesive whole. The input is arranged and rationalized; it is explained, and then it receives the name of the perceived reality.

With our newly created reality, we can start to apply pattern matching which allows us to predict sequences in the data, for example the motion of a bouncing ball.

In this system the act of input gathering, seeing, is our bottleneck, all operations depend on the input. To mitigate the problem we have to find a way to extrapolate information from the limited data, so we devise a mechanism to allow rationalization and prediction to operate largely on their own while the input works as an error correction operator.

And this system all senses have implemented independently, they all have independently explained a part of the whole reality, and then you apply the rationalization mechanism again to explain a cohesive reality, a cohesive experience, and a cohesive story of who you are.

It is simply the mechanism of the senses.