Neurophysiological responses to schizophrenia-associated communication abnormalities

Individuals with schizophrenia experience difficulty with interpersonal interactions, in part resulting from communication abnormalities that are common in the disorder, and to the expectancy effects from knowledge of the person's diagnosis. The auditory N400 event-related potential provides an objective measure of recognition of incongruent speech and thus is a potential tool to understand how listeners respond to disordered speech as a function of awareness of diagnosis.

In this study, participants listened to segments of conversation between two people in which the sentence final word was a normal ending, a word approximation, or a neologism while EEG was recorded. Participants were randomized to two groups: told that the speaker had a diagnosis of schizophrenia or not told about a diagnosis.

Participants who were not told that the speaker had schizophrenia displayed a significant N400 during both word approximations and neologisms. However, no significant N400 was observed for participants who were told that the speaker had schizophrenia.

Differential neurological responses to the same abnormal speech depending on whether the diagnosis of the speaker was known, indicate an early processing expectancy effect for abnormal communication to come from someone with schizophrenia. Such responses to abnormal speech in schizophrenia indicate an expectation of abnormality from individuals with schizophrenia, which has implications for understanding social exclusion of individuals with the disorder.