  We demonstrate theoretically and subsequently observe in experiment a novel
type of soliton interaction when a pair of closely spaced spatial optical
solitons as a whole is made partially incoherent. We explain how the character
of the soliton interaction can be controlled by the total partial incoherence,
and show a possibility to change the soliton interaction from attractive to
repulsive, or vice versa, near a certain threshold in the coherence parameter.
