  We point out that the measurement of target spin depolarization $D_{nn}$ in
the $\bar{p}p\to\bar{\Lambda}\Lambda$ reaction may test dynamical mechanisms
invoked to explain the proton spin puzzle revealed by polarized deep--inelastic
scattering experiments. In particular, models with {\it negatively} polarized
$\bar{s}s$ pairs in the proton wave function predict $D_{nn}<0$, whereas models
with {\it positively} polarized gluons would predict $D_{nn}>0$.
