text: In magnetically doped semiconductors, the local magnetic field is determined by the magnetization of the dopant ions which are distributed statistically. The spin of charge carriers precesses in this field. The motional character enters the picture by the fact that the charge carriers diffuse through the semiconductor, and that the electron and hole spins thereby experience a varying local magnetization and variations of spin precession. The motional-narrowing effect was studied in optical pump/probe experiments, where mobile singlet excitons were excited optically. The motional narrowing manifests in a peculiar temperature dependence of spin dephasing: The dephasing becomes slower at higher sample temperature where the exciton velocity becomes larger and the excitons more quickly experience environments with different magnetization.