Sorry I don't remember what Don's definition of MAP was (besides Middle Age Photographer which is certainly me), but I'll try to pick up on the theme from what I can remember.
My photography is certainly influenced by what I experienced early in life. I think its much more than simple nostalgia. The themes or characteristics of the subjects seem to hold steady through the years amended with new experiences as they are collected.
I think if one looks at the backgrounds of the Masters, one can see the same thing. These early influences keep surfacing strongly throughout their careers. Weston started as a painter and portratist. This background is underlying his work. Ansel Adams was deeply moved by Yosemite early in his life. He lived there as an adult and made his stake to prominence with photographs from there. Steiglitz was an urban sophisticate - and it shows. Plowden grew up in Middle America and has made fame photographing it. Gordon Parks made his mark portraying the social injustice of harsh discrimination - something he grew up with. These are just a few off the top of my head.
I don't think of MAP when I go out, at least conciously. But then, maybe I put myself back in the viewpoint of a young boy to find what fascinates me about the image in the lens.