This neurophysiological deficit in early visual processing can not be explained by differences in overall symptom severity, which was unrelated to N1 sink amplitude; instead, higher ratings of severity in auditory hallucinators are likely, at least in part, related to the subgroup classification itself. Furthermore, typical concerns of random effects attributable to small, heterogenous samples are untenable given the large sample and the lack of subgroup differences in demographic (gender, age, education, handedness, verbal IQ) or clinical variables (illness duration and onset).
