HCI Papers Cite HCI Papers, Increasingly So

We propose X-index -- the proportion of papers' citations coming from outside their research field -- and use this metric to analyze citations of CHI, UIST, and CSCW papers between 2010 and 2022. We found an overall decreasing X-index by several measures, indicating that HCI papers have been more and more likely to be cited by HCI papers rather than by non-HCI papers.