do we really see what we observe?
or do we define/shape what we can through our filtered understanding and consciousness?
We *never* see a thing 'as it is'. For one thing, our senses are incredibly limited: we see only a very small part of the electromagnetic spectrum, we hear only a small part of the sonic spectrum, and we smell only a small part of the range of chemicals that exist.
So, we are *always* limited by our senses. But, in addition, our senses often do some 'pre-processing' before the messages are even communicated to the brain. This pre-processing has been developed through evolution, but is limited to the environments of our ancestors and is unreliable in many situations (optical illusions, anyone?).
And then we get to the brain itself. Anticipation of a stimulus makes us more likely to inappropriately detect that stimulus. And we can frequently be mislead to not even see what is in our visual field. I once saw a video with people tossing a ball back and forth. Being asked to count the number of times the ball is thrown makes it very unlikely one will see a gorilla dance around in the scene.
Edit: This is called the 'Monkey Business Illusion'. Google it!
But, with all of this, we can compare notes, test our ideas, and come up with understanding.