Is the Left Hemisphere Specialized for Speech, Language, or Something Else

Abstract

Experienced Morse code operators showed significant right-ear superiority, indicating left-hemisphere lateralization, for the perception of dichotically presented Morse code letters. No significant lateralization was found for rapid monotically presented Morse code words. Subjects who did not know Morse code did not show significant lateralization when dichotically presented with a set of stimuli which included all Morse code letters; however, they showed a tendency toward left-hemisphere lateralization with a set of Morse code letters which were restricted in duration and presented at relatively low intensity. Our results show that articulability is not a necessary property of stimuli lateralized to the left hemisphere in dichotic listening; a possible further interpretation is that it is language rather than speech that is lateralized to the left hemisphere.