The problem of distinguishing the photocurrent caused by the drift of free polarons from that produced by polarisation of neutral excited species is discussed. New pump-and-probe technique with monitoring the average photoconductivity changes permits to overcome these difficulties when studying primary processes of free charge carrier photogeneration. Models of those processes are considered in conditions of fs UV-light pulse excitation of polymeric samples, and probing intermediate excited species by the photocurrent changes caused by delayed red pulses. Negative changes are indicative for the role of intermediate excited species like excitons and polaron pairs. Second order processes between polaron pairs seem to play a role in free polaron formation at high excitation rate.