The Fish and Scrivener article (9 pages!!!) is the "high level" read that describes how sketching and visual imagery helps us think. The Goldschmidt article (1991) is a well known paper that describes how design sketching and visual imagery supports design thinking. Everyone should read these two.
Half the group should read the Blanco article and half the Goldschmidt and Smolkov article - as an example of applying these ideas to design activity. The Blanco article looks at how sketching is used in collaborative design. The other article looks at how visual stimuli influences designing.