Excluding trials on which the participant “missed” the odor, and disregarding the participant’s high versus low intensity response, separate olfactory ERPs for high and low odor intensity were averaged from correctly detected, artifact-free trials using the entire 2-s epoch. To obtain more stable waveforms, ERPs were pooled across nostrils because of their blocked presentation order, and preliminary analyses did not reveal any effects of interest; furthermore, previous research has suggested that side of odor stimulation is of subordinate importance for measuring OERPs (e.g., Olofsson et al., 2006; Stuck et al., 2006). The mean number of trials (± SD) used to compute OERP averages were 30.7 ± 8.4 and 23.1 ± 8.9 (high vs. low intensity, respectively) for healthy controls and 30.0 ± 8.0 and 23.6 ± 8.5 for patients. As expected, more trials entered into high than low intensity ERP averages, F(1,63) = 45.3, p < .0001, but there were no differences between patients and controls. Visual inspections of the individual ERP waveforms also confirmed an acceptable signal-to-noise ratio for each participant. ERP waveforms were screened for electrolyte bridges (Tenke
