  The problem of the observer in quantum mechanics is getting new human
content. The paradox of Wigner's friend and its extended versions have
observers who not only observe quantum phenomena, but communicate, have
memories and even super-observer powers. Observers are represented by particle
paths and state memories and advanced AI has been suggested to act as an
observer. There is a new call for a solid theory of the observer in quantum
mechanics. Two different branches of observer theories have emerged. The purely
physical one is Heisenbergian, e.g. relational quantum mechanics where the
observer is considered as any other physical quantum system. The other branch
is psychologically rich as its observer has complex human faculties such as a
mind, mental states and memory (Many minds), or the observer is considered as
an active and experiencing agent, with continuously refreshed, scientific
expectations (QBism). Is the human observer a special case, different from
other quantum mechanical systems? Why is there no theory of the general
observer in quantum mechanics? A historical summary is covered on how quantum
mechanical interpretations have treated the observer, and the concept of hidden
human variables is suggested to continue the discussion on the theoretical
nature of the observer.
