cognition is not reducible to something tangible

I realized that physical stimuli lead to appropriate sensory responses.
But if the stimulus is not physical; rather, an internally initiated stimulus rooted from concepts, the response is most of the time also conceptual. And the response is fleeting.
All empirical representations of one's ideas and concepts are therefore attempts to capture the fleeting response. And these empirical representations are subject to multiple interpretations by other individuals.
The point is, the exact conceptual response of the individual from which it sprouted can never be truly and completely understood/ experienced by anyone else except the aforementioned individual.