Neurological Adaptation in Expert Rappers
Expert lyricists were compared to demographically similar non-lyricists in their judgment of non-word sequences in terms of their level of rhyme congruence (see key below) using EEG.
Full: vowels match; consonants match
Half: vowels match; consonants differ, with matched voicing (favorable) , or different voicing (unfavorable, circled)
Non: vowels differ; consonants differ
The figure above shows EEG responses of lyricists and non-lyricists to full-rhyme, unfavorable half-rhyme (different voicing) and non-rhyme. Non-lyricists processed all conditions as distinct at electrodes above brain regions specializing in language structure, but processed conditions as non-distinct for regions specializing in music structure. By contrast, lyricists processed full-rhyme and unfavorable half-rhyme similarly in the left hemisphere, but distinct from non-rhyme, while in the right hemisphere, they processed non-rhyme and unsatisfactory half-rhyme similarly but distinct from full-rhyme.
Findings suggest that lyricists have neuroplastically adapted to a "musico-linguistic" syntax for the integration of music and language elements. In this proposed adaptation, words are processed in the left-hemisphere as either rhyme or non-rhyme, based on whether words have identical vowels; thus, full- and half-rhymes are treated as the same. Final consonants for full- and half-rhymes are treated as a separate grammatical marker that determines whether the word sequence is musically appropriate, which is processed in the right-hemisphere, where both non-rhymes and unfavorable half-rhymes are treated as the same, namely, as inappropriate conclusions to the established rhyme phrase structure.