This paper explores whether facial microexpression state (FMES) changes can be used to identify moments of conceptual conflict, one of the pathways to conceptual change. It is known that when the preconditions of conceptual conflicts are met and conceptual conflicts are detected in students, it is then possible for conceptual change to take place. There were 102 university and high school students who were involved in this research, and about 80% of the participants held erroneous preconceptions on the scientific topic chosen. The results showed that FMES changes were detected in the majority of the students who made erroneous predictions as they underwent conceptual conflict. Furthermore, the lack of FMES change was shown to indicate a lowered likelihood of conceptual change, while the presence of FMES change doubled the likelihood of conceptual change. The results confirm that FMES can be useful in determining learners' awareness of conflicting concepts and their progress towards scientific understanding. Educational implications are discussed.