Spatial constraints on focused attention: beyond the right-side advantage.

The subjects listened to one of two simulataneous synthetic speech syllables delivered independently over two loudspeakers. When the loudspeakers were situated at 90 degrees to the left and to the right, right-side advantage was found. When one loudspeaker was situated in front of the subject in the median plane, and the other at one of several azimuthal positions around him an advantage of the frontal position was observed in all cases. On the other hand, performance on the nonfrontal message was affected significantly by its position. The pattern of performance which is presumably to cerebral dominance, an advantage of sources situated in front of the subject over those at his back, and possibly an advantage of sources near the median plane over more remote ones.