Asymmetric citation behavior

Our colleague James Rising indirectly pointed me to a PNAS paper from 2008 by Rosvall and Bergstrom that provides a very interesting map of citation structure across the entirety of the sciences [click through for larger versions]:

As noted in the lower right, arrows convey intensity of citation from one field to the next. The structure is very similar to that revealed by eigenfactor.org's plots (previously blogged here; apparently at least one of the authors is involved in the eigenfactor project) albeit with some additional and rather useful dimensionality.

Or particular interest is the social sciences, which Rosvall and Bergstrom map out in detail:

Note how high the flow intensity within economics (circle darkness) is compared to flow outside (circle border), as well as the relative patterns to other fields, almost all of which cite economics more than economics cites them. The pattern is similar though not quite as extreme for psychology. There are a variety of reasons one could imagine for this (rigor of work, differences in strategic citation behavior, range of topics studied, etc. etc.) but it's a pretty nice bit of academic-social network structure to ponder on its own.

The structure of human knowledge

Following up on Jesse's post:

After dinner today I told Brenda that I wanted a network map of all papers ever written so we could see where the biggest gaps in human knowledge were. In moments she had us browsing the site well-formed.eigenfactor.org looking at a coarser approximation of my dream (see picture).

I highly recommend any academic or casual intellectual browse the highly interactive site, it is simply too interesting, beautiful and [maybe] important to ignore.

Perhaps the two most striking observations one can make from simple visual inspection are that (1) biologists write a lot of papers and (2) social sciences/mathematics/computer science are extremely insular (observe the big "hole" in the network picture).

I'll let the data speak for itself (please please look at the site); but the only thing I'll say is that if anyone wanted to create a new field, bridging the social and physical sciences looks like a conspicuously good place to start.

Interdisciplinarity isn't easy

I'm currently wrapping up edits on a paper on interdisciplinarity and research success and came across a pretty cool paper for my lit review with a couple of choice quotes:

"[T]he young scientist, who grows up in the midst of a competition between university departments and amidst competition within his department, who inherits the individualistic research tradition and graduates without having had an opportunity to develop skills in cooperative thinking and collaborative study, is poorly prepared to participate in the activities of a committee or a research team.

"Over and above this pressure from the outside, there are important scientific grounds why interdisciplinary (and interdepartmental) research should become a greater concern of the universities. The assertion that institutes of an interdisciplinary character will be associated more often with industrial enterprises than with universities may be correct in the statistical sense, but it should not imply that cooperative research is an industrial prerogative.

"For the research worker who has grown up in the traditional departmentalized university and who is anxious to take part in interdisciplinary work, the first step is to get a bird's-eye view of the neighboring fields and to obtain familiarity with the problems which are currently the foci of interest. However, text-book acquaintance is not enough; some contact with actual work methods is essential. "

I think these are all reasonably fair points. The problem is that this article is from the December 8th, 1944 issue of Science. Reading through it and noting how little change there's been in the language around "interdisciplinary research" is fairly shocking, and makes me appreciate not only how difficult working outside of one discipline is, but also the extent to which the road towards doing quality work combining the social and natural sciences (which is probably the best way to describe the specific flavor of interdisciplinarity that Sol and I are in) has been a long and arduous one.

Not that there hasn't been any progress, mind you. The flip side of interdisciplinary work is field creation. Climatology, neuropsychology, behavioral economics, and an untold number of additional academic disciplines were all, at one point, "inter-discipline." It's just nice to be reminded of the fact that establishing those fields isn't easy.