Categorizing personal characteristics into a three-tier fashion nicely
fits Murstein's (1970) partner selection theory—the stimulus–value–
role theory, which suggests that people gain three different types of information
about their partner as relationships progress. The first type is
“stimulus” information, typically obtained at the beginning of a relationship.
Stimuli include highly visible and easily identifiable characteristics
such as demographic variables. When partners are satisfied with each
other's stimuli, they progress to the next stage where they seek
“value” information of each other, including important attitudes, values,
and other preferences. If both partners are happy with each other's
values, they move on to the last stage—the “role” stage, where they determine
if their roles in the relationship are compatible. This largely depends
on the two partners' personalities.