Impaired Self-Monitoring of Inner Speech in Schizophrenia Patients with Verbal Hallucinations and in Non-clinical Individuals Prone to Hallucinations

Abstract

Background: Previous research has shown that various memory errors reflecting failure in the self-monitoring of speech were associated with auditory/verbal hallucinations in schizophrenia patients and with proneness to hallucinations in non-clinical individuals.Method: We administered to 57 schizophrenia patients and 60 healthy participants a verbal memory task involving free recall and recognition of lists of words with different structures (high-frequency, low-frequency, and semantically organisable words). Extra-list intrusions in free recall were tallied, and the response bias reflecting tendency to make false recognitions of non-presented words was computed for each list.Results: In the male patient subsample, extra-list intrusions were positively associated with verbal hallucinations and inversely associated with negative symptoms. In the healthy participants the extra-list intrusions were positively associated with proneness to hallucinations. A liberal response bias in the recognition of the high-frequency words was associated with verbal hallucinations in male patients and with proneness to hallucinations in healthy men. Meanwhile, a conservative response bias for these high-frequency words was associated with negative symptoms in male patients and with social anhedonia in healthy men.Conclusion: Misattribution of inner speech to an external source, reflected by false recollection of familiar material, seems to underlie both clinical and non-clinical hallucinations. Further, both clinical and non-clinical negative symptoms may exert on verbal memory errors an effect opposite to that of hallucinations.

Voice-selective prediction alterations in nonclinical voice hearers

“…Thus, a prediction error may arise from the comparison of a less specific/accurate prediction with the available sensory feedback. A less specific prediction may imply altered self-monitoring of speech, which has been consistently associated with AVH 34 , 36 , 37 , 59 – 62 .…”

“…However, they are also present in 6–13% of general population 32 , 33 . The experience of AVH in psychotic and nonpsychotic individuals seems to engage similar cognitive mechanisms and brain areas 34 , 35 . This suggests a neural substrate specific to AVH rather than schizophrenia.…”

“…A substantial body of evidence shows that a failure to distinguish between internally and externally generated sensory signals (e.g., one’s own voice vs . somebody else’s voice) may underlie the experience of AVH 34 , 36 , 37 . This is reflected in a reduced N1 suppression effect when listening to real-time feedback of one’s own voice 6 , 11 , 38 or in button-press tasks (contrasting self-initiation of a sound with passive exposure to the same sound) 13 .…”

Motor representations underlie the reading of unfamiliar letter combinations

“…In the same direction, a groundbreaking result was reported by Anumanchipalli and colleagues 30 , who mounted a neural decoder based on articulatory dynamics capable of synthesizing speech when a participant silently mimed sentences. These results show that investigation on inner speech has direct implications in the development of devices to restore speech 31 , and also in other fields as psychiatry, where failure in the monitoring of inner speech has been associated with verbal hallucinations in schizophrenia 32 . However, not so much attention has received the motor processing during silent reading.…”

Ocular dynamics reveal articulatory processing at single-phoneme level during silent reading

“…In the same direction, a groundbreaking result was reported by Anumanchipalli and colleagues [28], who mounted a neural decoder based on articulatory dynamics capable of synthesizing speech when a participant silently mimed sentences. Investigation on inner speech has direct implications in the development of devices to restore speech [29], and also in other fields as psychiatry, where failure in the monitoring of inner speech has been associated with verbal hallucinations in schizophrenia [30].…”