Auditory-Visual Speech Processing (AVSP'99)
August 7-10, 1999
Scalp electrical potentials (event related potentials - ERPs) were measured in right-handed hearing participants making a speeded choice to two types of facial image: images of speech ("oo" or "ee?") and images of expression ("happy" or "sad?"). A different spatial distribution of brain electrical activity was found for the two tasks. While the early-latency P1 potential was distributed similarly for the two tasks, the face-sensitive N170 waveform showed task sensitivity. The N170 showed greater left hemisphere (LH) localization for the speech classification task, but more bilateral, or right hemisphere (RH) localization for the expression classification task. The precise pattern depended on whether a full-face (Experiment 1) or a half-face (Experiment 2 ) was seen but was similar for both. The N170 has not previously been shown to be influenced by the nature of an active decision in a face processing task..
Bibliographic reference. Haan, M. de / Campbell, Ruth (1999): "Lateralized Event-Related Cortical Potentials In Discriminating Images Of Facial Speech", In AVSP-1999, paper #6.