Strohminger and Nichols research (Cognition 131 (2014) 159–171) indicates that people consider moral traits to be more important than memory for identity. This is perhaps not so surprising, although the philosophical literature hadn’t really been looking at consistency of moral traits, focusing instead on other psychological characteristics, especially memory, or on physical continuity.
But it implies a disturbing conclusion when combined with situationist accounts of ethics. If, as writers like Doris (Lack of Character, Cambridge, 2002) and Gilbert Harman claim, our ethics are not so much based on our character traits but our environment, then it seems that personal identity is not internal, but environmental.
Or at least it is if we take the popular view that moral character is essential to identity, and we accept the situationist’s results. We could claim that the common view is wrong, that ethics are not a necessary part of identity. Or we could note that our internal character traits, even on situationist accounts, do provide some part of our ethical makeup, just not the overwhelming or decisive part. Then we could say that that part of our ethical makeup is where identity resides.
Still it would be interesting, and fruitful, to look at how identity is environmental; we may, in some sense, become different characters in differing environments, and even, in a real and important sense, become different people.
That is, if our character can be radically altered, we may not recognize ourselves in our actions, and those who know us best may also not recognize us. An environmental notion of identity could capture these changes and produce an expanded sense of character, self and person. Who we are and where we are may be more deeply linked than the idea of the discrete individual, containing him or herself inside of skin-boundaries and across time, can account for.
Popular Metaphysics 