Both theories discuss how individuals and groups control or regulate access to
themselves (i.e., both illustrate the limited-access approach). Both theories describe
our need for privacy as a continuing dynamic of changing internal and external
conditions, to which we respond by regulating privacy in order to achieve a desired
level of privacy. In turn, achieved privacy can affect internal states and external
conditions. Both agree that attempts to regulate privacy may be unsuccessful:
we may achieve more or less privacy than we desired. Both agree that privacy
can take many forms. Both agree that privacy has universal characteristics and
that the nature of the forms that privacy can take is probably culturally-specific.
Both agree that privacy can support illegitimate goals. Both differentiate the forms
(or the hows) from the functions (or the whys) of privacy. Both agree that the
functions of privacy include opportunities for self-evaluation and that privacy
contributes to self-identity and individuality. The principal difference is that
Altman’s theory is relatively inclusive of privacy phenomena because it emphasizes
social interaction but Westin’s is less so, often focusing on information privacy,
a subset of social interaction. (In this regard, CPM theory also focuses on information
privacy.) That two independent, well-supported theories share so much in
common suggests that they provide a reasonable foundation for understanding the
fundamentals of privacy as a psychological concept.