TY - JOUR
T1 - "McGurk illusion" to bilateral administration of sensory stimuli in patients with hemispatial neglect
AU - Soroker, Nachum
AU - Calamaro, Nir
AU - Myslobodsky, Michael
N1 - Funding Information:
between the lip-read and masked auditory stimuli from 0 to 800 msec, subjects' ability to repeat words is barely affected I-3, 6\]. In a similar vein, the ventriloquist illusion is achieved even when a visual cue is provided at a point at 135 ° away from auditory input \[2\]s uggesting that some template that processes AV input tolerates spatial disparity, thereby suggesting that these modalities do not map perfectly onto each other. It is tempting to speculate that the blending of conflicting bilabial and velar syllables into alveolar with no awareness of discrepancy is an example of such tolerance of disparity exhibited by the neuronal net. As in a case of the ventriloquist illusion, here too, visual input determines the phonetic structure of the output. The ethological advantage of such a template is in its ability to be utilized either as a computational map solely for spatial orientation or to provide visual-spatial coordinates which can take into account the place and manner of articulation of auditory stimuli for linguistically relevant distinctions. Also, it permits normal human subjects to shield lip-read information in a durable code for subsequent integration with auditory input \[3, 6\], Acknowledgements--This work was supported by The Israel Academy of Sciences grant to M.S.M. We thank Dr C. Serfaty for her unfailing aid in neuropsychological and neurologtcal testing of some of these patients, Dr J. Glicksohn for advice in statistical processing, Dr A. Martin and M. Lapidot for comments on the earlier draft of the manuscript and S. Sher for help in technical execution of the project.
PY - 1995/4
Y1 - 1995/4
N2 - The illusion of McGurk (Nature 264, 746-748, 1976) refers to the blending of conflicting audio-visual messages. By taking advantage of this phenomenon the study explored whether visual cues (i.e. manner of articulation) in ipsilesional (right) space would help a patient with auditory neglect to mentally reconstruct syllabic sounds voiced in contralesional (left) space. We examined seven patients with clinically detectable visual neglect following right hemisphere damage. All had signs of auditory neglect as documented by the inferior identification of syllables delivered through a loudspeaker on the left side. In contrast, syllabic sounds delivered contralesionally together with visual stimuli in the ipsilesional space significantly increased identification of "neglected" syllabic sounds. Of the increased responses, 23% were classified as illusory blends, thereby suggesting that manner of articulation provides a valuable clue as to the possible "best fit" for a consonant. The susceptibility to the blend illusion was identical in patients and controls. Results indicate that neglected auditory stimuli are retrieved in patients with right hemisphere lesion by the mechanism of the ventriloquist illusion in the presence of a carefully timed sequence of comparisons of auditory signals in the neglected space with visual signals in the attended space. The possibility that neuronal mechanisms that serve audio-visual merger in spatial localization are also utilized for processing speech distinctions is discussed.
AB - The illusion of McGurk (Nature 264, 746-748, 1976) refers to the blending of conflicting audio-visual messages. By taking advantage of this phenomenon the study explored whether visual cues (i.e. manner of articulation) in ipsilesional (right) space would help a patient with auditory neglect to mentally reconstruct syllabic sounds voiced in contralesional (left) space. We examined seven patients with clinically detectable visual neglect following right hemisphere damage. All had signs of auditory neglect as documented by the inferior identification of syllables delivered through a loudspeaker on the left side. In contrast, syllabic sounds delivered contralesionally together with visual stimuli in the ipsilesional space significantly increased identification of "neglected" syllabic sounds. Of the increased responses, 23% were classified as illusory blends, thereby suggesting that manner of articulation provides a valuable clue as to the possible "best fit" for a consonant. The susceptibility to the blend illusion was identical in patients and controls. Results indicate that neglected auditory stimuli are retrieved in patients with right hemisphere lesion by the mechanism of the ventriloquist illusion in the presence of a carefully timed sequence of comparisons of auditory signals in the neglected space with visual signals in the attended space. The possibility that neuronal mechanisms that serve audio-visual merger in spatial localization are also utilized for processing speech distinctions is discussed.
KW - McGurk illusion
KW - audio-visual neglect
KW - ventriloquist illusion
UR - http://www.scopus.com/inward/record.url?scp=0028966601&partnerID=8YFLogxK
U2 - 10.1016/0028-3932(94)00130-H
DO - 10.1016/0028-3932(94)00130-H
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C2 - 7617155
AN - SCOPUS:0028966601
VL - 33
SP - 461
EP - 470
JO - Neuropsychologia
JF - Neuropsychologia
SN - 0028-3932
IS - 4
ER -