A mental representation can mean an abstract thought (i.e. rhythm or phrasing) that is partially represented using a physical analogy or diagram.
Example: In Bamberger’s chapter “Coming to Hear in a New Way,” Bamberger speaks of two students, Met and Mot, who attempt to represent the rhythm and emphasis of a simple phrase (referred to as the “class piece” (p 135)) by means of a sequence of large or small circles.
Mot’s Diagram: OOoooOOooo
Met’s Diagram: OOooOOOooO
Both have different interpretations on the correct way to notate the phrase, and both are correct because each represents a different form of hearing, namely figural and metric forms respectively. (Bamberger 1994, p 138-146)