Kelley (1952) has made a valuable distinction between reference group and membership
group. Reference groups are groups that are psychologically significant for people's attitudes
and behaviour, either in the positive sense that we seek to behave in accordance with
their norms, or in the negative sense that we seek to behave in opposition to their norms.
Membership groups are groups to which we belong (which we are in) by some objective
criterion, external designation or social consensus. A positive reference group is a source of
conformity (which will be socially validated if that group also happens to be our membership
group), while a negative reference group that is also our membership group has
enormous coercive power to produce compliance. For example, if I am a student but I
despise all the attributes of being a student, and if I would much rather be a lecturer
because I value lecturer norms so much more, then 'student' is my membership group and
is also a negative reference group, while 'lecturer' is a positive reference group but not my
membership group. I will comply with student norms but conform to lecturer norms.