Role shifting is an indexing part of the grammatical structure of ASL. It indicates who says and/or what a character does. This grammatical device is commonly used in dialogues or what is called "Direct Address" narrative between two characters or persons.
The signer moves his body, head, and/or eyes to the right or to the left to assume the role of the person or character. She also takes on other affective or characteristic traits of the role or character.
Body shifting, gaze shifting, and head shifting are the common role shifting techniques.
Head tilting is used to represent two roles or characters of different heights (e.g. an adult and a child, a human and a pet, a cat on the tree branch and a human on the ground, etc).
The Zen master, who just had arrived home, entered the house and was surprised to see somebody there.
The thief was startled and nervous.
But the master was moved, "Wow, you [came all the way over here.]"
This video clip from the Zen parable Moon Cannot be Stolen shows an example of the storyteller switching two roles, using body, eye, and head shifting: the Zen master and the thief. The storyteller uses role shifting (another form of indexing) to indicate which character is speaking and/or acting.
Two goats [classifiers] face each other on a thin bridge.
The storyteller in the video clip above from the story The Goats and the Bridge uses body-shifting, gaze shifting, and indexing (finger-pointing) to indicate the characters or subjects. Dialogue or direct address is also used in this clip.
In this fable, the signer first signed the noun goat before using the classifier and indexing which function as a pronoun throughout the fable or until the subjects change in space.
Personification is another role-shifting device that can be used in ASL storytelling. A storyteller uses a classifier, facial expression, and/or characteristics of the character.