  We analyze the axial-vector form factors of the nucleon-hyperon system in a
model with SU(3)$_{\text{flavor}}$ symmetry breaking due to mass dependent
quark spin polarizations. This mass dependence is deduced from an analysis of
magnetic moment data, and implies that the spin contributions from the quarks
to a baryon decrease with the mass of the baryon. When applied to the
axial-vector form factors, these mass dependent spin polarizations bring the
various sum-rules from the quark model in better agreement with experimental
data. As a consequence our analysis leads to a reduced value for the total spin
polarization of the proton.
