[en] A neutron-number (N) dependence of analyzing powers A (theta) has been observed for the first time in (polarized p, t) reactions leading to the quadrupole vibrational states (2₁⁺) in ⁹⁸Ru, sup(102,108)Pd, ¹¹⁴Cd, ¹¹⁶Sn, and sup(120,126)Te. Although analyzing powers for the ground-state transitions A(theta,0 sub(g)sup(+)) are very similar to each other, those for the 2₁⁺ transitions A(theta,2₁⁺) for the nuclei belonging to the beginning of the N = 50 - 82 shell are markedly different, having almost opposite signs, from A(theta,2₁⁺) for nuclei belonging to the latter half of the major shell. The difference is explained as a result of a sign change of the interference between one- and inelastic multi-step processes in two-neutron pickup reactions. Nuclear structure effects on such an interference are discussed on the basis of the microscopic description of collective quadrupole oscillation of nuclei. (author)