1. Visualizing Critical Trails of Scientific Knowledge Chaomei Chen, Drexel University Panel on Mapping Science Society for Social Studies of Science Annual Meeting in Pasadena, 20-22 October, 2005

2. Questions How does scientific knowledge evolve? If there is a such thing as a paradigm, where can we find its fingerprints, footprints, or both? Can we X-ray or video type the evolution of scientific knowledge and find the most critical pathways? Can we make science maps so that one could see where intellectual sharp turns were made, conceptual gulfs were bridged, and lessons learned were diffused?

3. Approach Social networks Weak ties, structural holes, knowledge diffusion Intellectual networks Research fronts, intellectual bases, conceptual revolutions, paradigm shifts, turning points CiteSpace – an evolving tool for detecting and visualizing emergent trends and changes in scientific literature Citation networks, co-citation network, hybrid networks Examples Conceptual revolutions: string theory; accelerating universe Scientific debates: mass extinctions; global warming Response to external events: terrorist attacks Scientific evidence: NSAID or Vioxx

4. Social Networks: Weak ties and Structural Holes

5. “Creativity is the friction of the attention space at the moments when the structural blocks are grinding against one another the hardest ” The philosophers of greatest repute tended to be rivals representing conflicting schools of thought for their generation. Collins 1998, p. 76

6. Social Network of Coauthorship

7. 1 2 3 A B C Structural Hole Measures Betweenness Centrality Core/Periphery Class Density matrix 1 2 ----- ----- 1 0.280 0.007 2 0.007 0.002 Weak Components

8. Structural and Temporal Patterns Are maps valid representations of scientific fields or of science as a whole, and what are the viable approaches to validation? –Terrorism (1990-2004), domain experts at pivotal points –String theory (1990-2004), domain experts at pivotal points What social and intellectual realities do they capture, or fail to capture? –IST co-authorship (1990-2005) Can scientific controversies be represented by maps and what do they look like? –Global warming debates –Mass extinctions debates –Vioxx, evidence Can maps inform us about the history of a field? –Terrorism, Mass extinctions Do they reflect a “collective mind” of science, or are they merely artifactual aggregates of particularistic behavior? Finally, what is the audience for such maps: the scientific elite or the masses?

9. An animation of botox research http://www.pages.drexel.edu/~cc345/ video/citation_land_local.avi http://www.pages.drexel.edu/~cc345/ video/citation_land_local.avi

10. Intellectual Networks

11. The Approch Structural and Temporal Analysis –Intellectual turning points –Emerging themes before …after!

12. Why Scientists Cite? Normative View –Citations are made because of the intellectual values of cited works. –They should not be affected by social and cultural characteristics such as race, gender, or academic rank.

13. Why Scientists Cite? Social Constructivist View –Scientific knowledge is socially constructed and motivated by political and rhetorical reasons. –Scientists use citations primarily as tools of persuasion. –Citations serve as a vehicle to enlist the support of eminent authors and win over readers.

14. Why Scientists Cite? Which way is it? –Stewart, J. A. Drifting Continents and Colliding Paradigms: Perspectives on the Geoscience Revolution. Indiana University Press, 1990. –Baldi, S. Normative versus social constructivist processes in the allocation of citations: A network-analytic model. American Sociological Review, 63 (6). 829-846. –White, H.D., Wellman, B. and Nazer, N. Does citation reflect social structure? Longitudinal evidence from the 'Gobenet' interdisciplinary research group. Journal of the American Society for Information Science and Technology, 55 (2). 111-126. Scientists tend to cite papers because of their intellectual values!

15. What Scientists Cite? Foundational papers Recent papers foundational recent

16. What Scientists Cite? Foundational papers Recent papers Hargens, L.L. Using the Literature: Reference Networks, Reference Contexts, and the Social Structure of Scholarship. American Sociological Review, 65 (6). 846-865. foundational recent physics, biomedicinesociology, psychology

17. Paradigm Shift Normative –Citations reflect intellectual values. Recentness –Citations register new concepts and new associations. turning point

18. CiteSpace Multipartite networks –Author, Article, Keyword –Co-authorship, co-citation, citation Time Slicing –Filter out the effects of long-range citations –Divide and conquer Threshold-Based Interpolating –Select the cream of the crop across the board Burst Detection –Surge of node attributes, surge of link attributes Pruning –Minimum Spanning Tree –Pathfinder Network Scaling Graph-Theoretical Analysis and Clustering –Centrality –Citation Half-Life

19. PubMed Google Scholar CiteSeer Web of Science ACM DL Topic search “terrorism”

20. Design citing author citing author co-authorship cocitation cited author or paper cited author or paper extracted keyword extracted keyword topic- reference centrality annual citations surge MST Pathfinder

21. Expected Patterns Thematic grouping Intellectual turning points Thematic change over time Abrupt changes associated with triggers

22. Validated by Experts String Theory –Physicists Terrorism –Physiatrists –Medicine –Political Science Mass Extinction –Ocean Paleontologist

24. ACA DCA Co-Authorship JCA Co-Term (Burst)

25. 1994-2004 N=469, E=1,798

30. 27 Biological Warfare 17 Violence 14 Bioterrorism N=93 N=45 11 Stress Disorders, Post-Traumatic/*epidemiology 9 Terrorism/*psychology 8 Disasters N=31 11 Explosions 7 Violence 4 Blast Injuries/*mortality

31. Evolving over time

43. MeSH

44. Summary 1.Scientific literature reflects the underlying changes in scientific paradigms. 2.Deeper processing is necessary to sharpen the big picture of intellectual changes. 3.Given the structural and temporal scale, complexity, and dynamics of a knowledge domain, there is still a long way to go to turn a challenging and fascinating ambition to pragmatic and everyday tools and applications.

45. The CiteSpace Homepage http://cluster.cis.drexel.edu/~cchen/citespace http://cluster.cis.drexel.edu/~cchen/citespace