VP ]: ▁small ▁to ▁large ▁interval , ▁same ▁reg ist ral ▁direction ▁ ▁inter v all ic ▁revers al ▁[ IR ]: ▁large ▁interval ▁to ▁small ▁interval , ▁same ▁reg ist ral ▁direction ▁ ▁reg ist ral ▁revers al ▁[ V R ]: ▁large ▁interval ▁to ▁larger ▁interval , ▁different ▁reg ist ral ▁direction ▁ ▁inter v all ic ▁dup lication ▁[ ID ]: ▁small ▁interval ▁to ▁identical ▁small ▁interval , ▁different ▁reg ist ral ▁directions ▁ ▁Each ▁of ▁these ▁ 8 ▁fundamental ▁symbols ▁can ▁refer ▁to ▁a ▁" pro s pective ▁or ▁ret ros pective ▁dimension ". ▁The ▁symbols ▁are ▁en closed ▁in ▁parentheses ▁like ▁so : ▁( V R ) ▁to ▁indicate ▁a ▁" ret ros pective ▁real ization ". ▁N arm our ▁( 1 9 9 0 , ▁ 6 ) ▁cons iders ▁these ▁symbols ▁to ▁be ▁representative ▁of ▁cogn itive ▁structures : ▁" As ▁sym b ological ▁tokens , ▁all ▁six teen ▁pros pective ▁and ▁ret ros pective ▁letters ▁pur port ▁to ▁represent ▁the ▁listener ' s ▁encoding ▁of ▁many ▁of ▁the ▁basic ▁structures ▁of ▁mel ody ." ▁ ▁From ▁these ▁found ations , ▁the ▁theory ▁gets ▁more ▁detailed , ▁and ▁problems ▁of ▁style , ▁pitch , ▁harm ony , ▁rh ythm , ▁etc . ▁are ▁all ▁discussed . ▁ ▁S ynt actic ▁paramet ric ▁scale ▁ ▁Top - down ▁and ▁bottom - up ▁processing ▁ ▁Five ▁principles ▁Sch ellen berg ' s ▁work ▁has ▁involved ▁testing ▁and ▁simpl ifying ▁specific ▁implementations ▁of ▁the ▁I - R ▁model .