While we were discussing this example, an interesting phenomenon occurred - the aha factor, or the emotional response of discovery. Most of us embraced the spiral as an interesting alternative way to understand the heapsort and its subsequent modification, but Robert Biddle in particular jumped up, virtually grabbed node 1 of the spiral, and virtually shook out the spiral as if it was a solid object. The mental model most of us had was of a christmas tree, with the tree nodes appearing as tree lights down each side of the conical spiral. This seemed a perfect demonstration of the power of a 3-D mental model. With such a visualization we were all able to see many properties at once, in an integrated and consistent fashion more sharply than before.
Another interesting phenomenon occurred - a group think, where everyone in the group was trying to make sense of the diagram with respect to a heapsort that wasn't defined formally. Most of us had experience with heapsort specifically and with data structures in general, and the level of the discussion reflected this. What we never put in front of us was a specific form for the algorithm. We were content to let the abstract mental model of heapsortedness guide our discussion.