[omgam]

One example might be that spirits are said to be bound by arbitrary functions (bizarre ritual ingredients being a famous example). That they respond to and recognize cues.

Another aspect of spirit lore is that the more central or higher in the hierarchy, the less different "pointers" or cues may be required for evocation, and stronger expression of those fewer cues may result. The lower/more numerous spirits might require more specificity or larger seed.

Transformations at a minimum: by inducing a receptive trance state, then by self-suggestion.