Greg Egan's "Closer" took the whole idea of distinct self in an interesting direction - tired of body swapping a couple totally sure each other's minds and immediate mental states. But instead of knowing each other better they formed a new self, a merger of their own selves.

Disturbed cognition featured in a lot of Phil Dick stories... tangent thought when I misread 'distributed' as 'disturbed'... , and distributed cognition has featured in a few SF tales - Mike Swanwick's "Stations of the Tide" is a good tale with a key character splitting up to handle many tasks, or Sheffield's "At the Eschaton" where the protagonist multiplies millions of times himself to lead a galaxy in a war.

But that's not quite what you mean I suspect. I'd like to see some more SF tackling themes like Egan has explored, especially his exploration of what living in an Everett-style multiverse means for self identity. Or even looking seriously at the "parallel cosmos" ideas Max Tegmark has written about in the context of spatially infinite Universes - that the Universe repeats on incredibly large scales (10^10^123 metres.)

Adam