The importance of external features for categorizing ethnicity: can Koreans identify Korean, Japanese, and Chinese faces?

To what degree is it possible to recognize a person's ethnicity just from their face? What information do you need to do so? Here, we present the first investigation addressing these questions, and in particular the role of internal and external facial features for fine-grained ethnicity categorization among closely related East Asian ethnicities. Specifically, we tested the ability of Korean participants to categorize male faces into Korean, Japanese, or Chinese ethnicities-a categorization that according to participants' own introspective opinion should be easily doable for them. Participants were randomly assigned to one of the three between-subjects conditions: an internal-only condition showing only internal facial features; an external-only condition in which internal features were blurred while hairstyle and face outline remained visible; and a full-face condition presenting both internal and external features. Our findings indicate categorization based on internal features only was barely above chance level, whereas both the full-face and external-only conditions resulted in more reliable above-chance performance-albeit at a low overall level of around 50%. Our study emphasizes the importance of external features in the accurate categorization of ethnic backgrounds, and establishes an overall low ability of Koreans to reliably distinguish between East Asian ethnicities.