We report measurements of the kinetic energy (${\mathit{E}}_{\mathit{k}}$) distributions of ${\mathrm{O}}^{\mathrm{\ensuremath{-}}}$ produced by low-energy electron impact (5.5--19.5 eV) on disordered multilayers of ${\mathrm{O}}_{2}$ physisorbed on a polycrystalline Pt substrate. The results confirm that dissociative electron attachment (DEA) proceeds via the formation of the $^{2}\mathrm{\ensuremath{\Pi}}_{\mathit{u}}$, $^{2}\mathrm{\ensuremath{\Sigma}}_{\mathit{g}}^{+}$(I), and $^{2}\mathrm{\ensuremath{\Sigma}}_{\mathit{x}}^{+}$(II) (x=g and/or u) states of ${\mathrm{O}}_{2}^{\mathrm{\ensuremath{-}}\mathrm{*}}$. We also find evidence for an additional resonance, namely the $^{2}\mathrm{\ensuremath{\Sigma}}_{\mathit{u}}^{+}$(I), positioned at about 10 eV above the neutral ground state in the Franck-Condon region, and dissociating into ${\mathrm{O}}^{\mathrm{\ensuremath{-}}}$+O${(}^{3}$P). The measurements suggest that the autodetachment lifetimes of the $^{2}\mathrm{\ensuremath{\Sigma}}_{\mathit{u}}^{+}$(I) and $^{2}\mathrm{\ensuremath{\Sigma}}_{\mathit{g}}^{+}$(II) states may be longer than previously suggested. It is also observed that the effects of electron energy loss (EEL) in the solid prior to DEA, ${\mathrm{O}}^{\mathrm{\ensuremath{-}}}$ scattering in the solid after dissociation, and the charge-induced polarization energy of the solid, broaden the ${\mathit{E}}_{\mathit{k}}$ distributions, shift them to lower anion energies, and result in additional structure in them. The effects of EEL on the desorption dynamics of ${\mathrm{O}}^{\mathrm{\ensuremath{-}}}$ are estimated from high-resolution electron-energy-loss spectra and excitation functions for losses in the vicinity of the Schumann-Runge continuum of the physisorbed ${\mathrm{O}}_{2}$ molecules. We find indications for an enhancement of the optically forbidden X $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}A $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ transition, and observe that the gas-phase Rydberg bands, for energy losses above 7 eV, are not distinguishable in the condensed phase.