i think you mean assumptions?.. meaning what do people assume about journeys/ imaginative journeys...
eg/ the assumption that in a journey one will travel from point a to point b, and the journey will conclude. "the ivory trail" challenges this assumption with the caption: "not all journeys have an ending"
-the assumption that imaginative journeys are not real, or that they take place in ones mind
.... i hope this helps... if you are still stuck then try and brainstorm some concepts around imaginative journeys... then in your essay, try and link or challenge these assumptions [if that is what they ask].