<p>This study leverages perceptual psychology methods to address a critical social psychological question: When selflessness and in-group favoritism conflict, which trait is more fundamentally intertwined with the essence of humanity? Specifically, it examines how people perceive and process the faces of those who lack in-group preferences or selflessness (i.e., perceptual dehumanization) and explores the functional significance of these perceptions (i.e., punishment). Experiment 1 involved participants evaluating out-group rescuers (lacking in-group favoritism) and in-group rescuers (lacking selflessness) when both groups simultaneously requested assistance. The findings revealed that out-group rescuers were consistently rated as significantly less humane than in-group rescuers. Experiment 2 employed a face re-recognition paradigm to explore differential face processing strategies—holistic processing for typical faces and feature processing for “dehumanized” faces. The results indicated that participants used more feature processing strategies (indicative of stronger perceptual dehumanization) when evaluating the faces of out-group rescuers. Experiment 3 investigated the social consequences of the absence of in-group favoritism or selflessness, revealing that participants exhibited stronger punitive impulses toward individuals lacking in-group favoritism. This highlights the functional role of perceptual dehumanization in shaping social responses. In summary, these findings suggest a bidirectional causal relationship between lower-order perceptual processes and higher-order cognitive processes in humanity perception, underscoring the profound impact of in-group favoritism on perceived humanity.</p>