  Exploiting the tension between the two dynamics of quantum theory (QT) in the
Wigner's Friend thought experiment, we point out that the standard QT leads to
inconsistency in observed probabilities of measurement outcomes between two
super-observers - Wigner and his Student. To avoid such inconsistent
predictions of QT, we hypothesize two distinct perspectives. The first one is
"Absoluteness of measurement (AoM)," that is, any measurement process is an
absolute event irrespective of other observers and yields a single outcome. The
other is "Non-absoluteness of measurement (NoM)" as the negation of AoM. We
introduce an operational approach, first with one friend and then with two
spatially separated friends, to test the validity of these two perceptions in
quantum theory without assuming the details of the experiment. First, we show
that the set of probabilities obtainable for NoM is strictly larger than the
set obtainable for AoM. We provide the simplest scenario so far, involving a
single quantum preparation and one unitary operation by a super-observer that
can demonstrate correlations incompatible with AoM. Remarkably, in the scenario
with spatially separated observers, we present a strict hierarchy among the
sets of probabilities observed in the following three theories: classical or
local realist, quantum theory with AoM, and quantum theory with NoM.
