Ah, I misinterpreted what you wrote in the OP. I suggest replacing this sentence in the OP
They generally reported greater differences between their earlier selves and their present than between their present and future selves.
with something like what you wrote in reply to nyan_sandwich (which I found much clearer):
Age X predicts less difference in the next 10 years than age X+10 recollects in the last 10 years.
Ah, I misinterpreted what you wrote in the OP. I suggest replacing this sentence in the OP
with something like what you wrote in reply to nyan_sandwich (which I found much clearer):