What does the y-axis represent?
For example, why does Behaviorism seem to have a bulge around the 1930s?
"Moving from left to right, the map is read in a roughly historical fashion, but not literally, as we are compressing a n-dimensional intellectual space into a two dimensional map grid."
I look forward to your future developments, this is really cool. I think some interactions with the diagram would be neat, for example clicking a bubble taking you to the corresponding Wikipedia article