Laterality tasks allow researchers to conduct experiments in which conflicting visual, auditory, or tactual stimuli are sent simultaneously to the two halves of the brain. These tasks allow researchers to measure whether the left or the right side of the brain copes better with the competing information. With visual laterality tasks, the signals are presented on a computer screen; with auditory laterality tasks, the signals are presented through stereo earphones; and with touch tasks, the stimuli are given to the right and left hands. When research participants receive the stimuli, the side of the brain that is dominant for that material will favor the information coming into the side that is contralateral, or opposite, to that hemisphere. In experiments using auditory laterality tasks, for example, researchers may present two words (e.g., “bin” and “pin”) or two excerpts of music simultaneously to a subject, who then may be asked to identify the words or melodies he or she just heard. The left side of the brain, which is dominant for language, will favor words coming into the right ear, and the right half of the brain, which is dominant for music, will favor melodies coming into the left ear.
