One reason to create a prototype is to anchor team conversations. Similar to the value of a map on the wall - we all look at the same thing and our conversation is about that. When we have a prototype on the table we are not each talking about the fantasy object or conceptual object in our own mind.

In this exercise we try to contrast a discussion with a model and a discussion without a model. Perhaps a third group that can do drawings on a white board?

Need to come up with a nice simple task.

Another version might be to create very deliberate extremetype models along a few dimensions to try to get a handle on those dimensions.

OR, use the concept of minimal pairs to isolate the effects of particular dimensions.