Jay emphasizes the compelling sense of this allure of immediacy. We believe that our perceptual and our introspective faculties give us an infallible representation of reality, and never question that it could be fallible.
This is very much aligned with the research on Umwelt by Jakob Von Uexkull.
Aperception, the introspection and awareness of our inner space is just as alluring.
So in summary:
perception gives us the feeling that we are sensing the way the external world actually is and aperception gives us the feeling that we are aware of the inner world as it is. However, both are relative, the first to our peculiar sense faculties and the second to our linguistic and conceptual modeling of reality. Both are specific filters that create the specific situated interpretation of reality as a human being.