This differs from the role of visible participants,
who are less effective in the policy stream
but more important in the problem stream and in getting items on the government agenda (Kingdon 1995, 30).
Kingdon (1995, 116) described the policy stream as consisting of a "policy primordial soup" in which multiple ideas are just "floating" around, waiting to be scooped up by prominent government actors.
The primordial soup is akin to the garbage can put forth by Cohen, March, and Olsen (1972).
Both problems and solutions get dumped into the same policy can, resulting in an unpredictable process of policy change.