Abstract / Summary
The eye region has an outsized influence on first impressions of faces. Its surface features, however, have been studied one cue at a time. This narrative integrative review proposes perceived ocular vitality as a unifying construct: an observer-side inference of youthfulness, health, and alertness drawn from the eye and periocular region. Five cue domains are evaluated: periocular contrast, scleral coloration, scleral exposure, limbal ring prominence, and iris luminance and framing. Evidence ranges from strong (periocular contrast; limbal ring health effects) to contested (the direction of the pupil-size effect). Two experimentally confirmed interactions, one so far shown only with non-human primate faces, suggest that the cues work jointly. Together they also expose confounds that single-cue designs miss. Chief among them, the limbal ring health effect appears to be carried substantially by scleral brightening. Within cue-based overgeneralization theory, the construct has two channels with pre-specified routing. Photometric cues carry youth and health to the valence dimension of face evaluation. Structural cues make the eye legible, which observers read as alertness, and are predicted to reach the dominance dimension as well. The construct is specified precisely enough to be falsified, and an analysis of an existing normed corpus could decide it.