Comparing point-wise and pair-wise relevance judgment with brain signals

How to collect relevance judgment has long been an important problem in Information Retrieval (IR). A popular method is to collect relevance judgment in a point-wise manner, in which assessors examine and give an absolute relevance score for each item independently of the others. As an alternative, pair-wise relevance judgment, also named preference judgment, allows an assessor to compare two items side-by-side and express their preference for one over the other. Previous work has explored the differences between these two paradigms of relevance judgments from many different aspects. Most of these works are conducted through explicit/implicit feedback. However, few works investigate the underlying neurological mechanisms of the two paradigms. In this paper, we conduct a lab study to investigate and compare point-wise and pair-wise relevance judgment in image search scenarios. We study the neurological mechanisms of the two paradigms through an event-related potential (ERP) analysis of the users' brain signals while viewing images during a search process. We have obtained several observations, such as search engine users tend to pay more attention to preferred items in the point-wise paradigm but unpreferred items in the pair-wise paradigm. Furthermore, we test the adoption of brain signals as implicit feedback for predicting pair-wise relevance judgment, highlighting the feasibility of leveraging brain signals to understand users' relevance judgments.