New results of photon echo, line shift and resonance light-scattering experiments aggregates of pseudoisocyanine bromide are reported and discussed. The temperature-dependent homogeneous width and shift of the J-band can be explained with a linear exciton-phonon scattering model. It is also shown that between 50 and 200 K, the aggregates's radiative lifetime is roughly proportional to the homogeneous width of the J-band. This finding is discussed on the basis of a relates the aggregate's radiative lifetime to its optical dynamics. Resonance light-scattering experiments show that the earlier noted discrepancy between the low-temperature photon echo and radiative lifetime cannot be due to a dynamical effect.