Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:In line with this observation, PCP induces in humans a behavioral changes including psychotomimetic activity, amnesia (Nishijima et al., 1996) and schizophrenia (Goff and Wine, 1997).
Category: