Impaired multisensory processing in schizophrenia: deficits in the visual enhancement of speech comprehension under noisy environmental conditions.
BACKGROUND
Viewing a speaker's articulatory movements substantially improves a listener's ability to understand spoken words, especially under noisy environmental conditions. In this study we investigated the ability of patients with schizophrenia to integrate visual and auditory speech. Our objective was to determine to what extent they experience benefit from visual articulation and to detail under what listening conditions they might show the greatest impairments.


METHODS
We assessed the ability to recognize auditory and audiovisual speech in different levels of noise in 18 patients with schizophrenia and compared their performance with that of 18 healthy volunteers. We used a large set of monosyllabic words as our stimuli in order to more closely approximate performance in everyday situations.


RESULTS
Patients with schizophrenia showed deficits in their ability to derive benefit from visual articulatory motion. This impairment was most pronounced at signal-to-noise levels where multisensory gain is known to be maximal in healthy control subjects. A surprising finding was that despite known early auditory sensory processing deficits and reports of impairments in speech processing in schizophrenia, patients' performance in unisensory auditory speech perception remained fully intact.


CONCLUSIONS
Thus, the results showed a specific deficit in multisensory speech processing in the absence of any measurable deficit in unisensory speech processing and suggest that sensory integration dysfunction may be an important and, to date, rather overlooked aspect of schizophrenia.
Ross
Lars A
LA
Program in Cognitive Neuroscience, Department of Psychology, The City College of City University of New York, 138th St. and Convent Avenue, New York, New York 10031, USA.
Saint-Amour
Dave
D
Leavitt
Victoria M
VM
Molholm
Sophie
S
Javitt
Daniel C
DC
Foxe
John J
JJ
D000328:Adult; D001076:Aptitude; D001288:Attention; D032882:Comprehension; D005260:Female; D006801:Humans; D008085:Lipreading; D008297:Male; D008875:Middle Aged; D010470:Perceptual Masking; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D013067:Speech Perception; D014796:Visual Perception