A gender effect was found for the N1 sink that differed across groups. Namely, healthy women showed greater N1 for the high concentration of H2S compared to healthy men, whereas schizophrenia patients showed the opposite gender effect. P2 also showed a gender effect, with women showing greater source and sink activity than men, but this was not dependent on group. Although Kopala, Clark, and Hurwitz (1989) originally reported that men with schizophrenia had greater olfactory impairment than women for smell identification, more recent studies by this and other groups have not replicated this gender effect (Kopala, Good, Martzke,&Hurwitz., 1995; Moberg et al., 1999; Seidman et al., 1997). Although we know of no reports examining gender differences in OERPs of schizophrenia patients, Becker et al. (1993) found larger P1/N1 and N1/P2 amplitudes for vanillin and H2S odorants in women compared to men in a sample of healthy and psychosis-prone subjects (i.e., gender differences were unaffected by group classification), and Stuck et al. (2006) also found larger P2 amplitudes to H2S in healthy women than men. Lundström and Hummel (2006), measuring ERPs
