Does an independent quasiparticle picture hold in mass-190 superdeformed nuclei?

We investigate the independent quasiparticle (QP) picture for superdeformed nuclei of the mass-190 region, which is expected to lead to additivity in certain physical quantities. Obvious deviations from additivity are found f rom both projected shell model calculations and experimental data. The caus e of the deviation can be decomposed and identified through this model. Our study suggests that the independent QP picture may not be fully appropriat e for this mass region.