Ultrafast time-resolved measurements on a semiconductor microcavity di
stinguish polariton dynamics dependent on the detuning between the con
stituent photon and exciton modes. Spectral synthesis allows the injec
tion of specific polariton pulses into the sample. Scattering which re
sults in absorption is found to be suppressed in the lower polariton b
ranch by the combined action of normal mode splitting and motional nar
rowing. The experimental difference between angle and position tuning
demonstrates the role of the polariton dispersion in polariton-polarit
on interactions.