<P> A transformation mask is a type of mask used by indigenous people of the Northwest Coast and Alaska in ritual dances . These masks usually depict an outer, animal visage, which the performer can open by pulling a string to reveal an inner, human face carved in wood . Northwest coast peoples generally use them in potlatches to illustrate myths, while they are used by Alaska natives for shamanic rituals . </P> <Ul> <Li> <P> Raven / Sisutl transformation mask by Oscar Matilpi, Kwakwaka'wakw Nation, 1997 . In the permanent collection of The Children's Museum of Indianapolis </P> </Li> <Li> <P> The same Raven / Sisutl transformation mask, open, by Oscar Matilpi, Kwakwaka'wakw Nation, 1996 . In the permanent collection of The Children's Museum of Indianapolis </P> </Li> </Ul>

How were transformation masks used in the original potlatch ceremonies