Putting culture under the 'spotlight' reveals universal information use for face recognition.

BACKGROUND: Eye movement strategies employed by humans to identify conspecifics are not universal. Westerners predominantly fixate the eyes during face recognition, whereas Easterners more the nose region, yet recognition accuracy is comparable. However, natural fixations do not unequivocally represent information extraction. So the question of whether humans universally use identical facial information to recognize faces remains unresolved. METHODOLOGY/PRINCIPAL FINDINGS: We monitored eye movements during face recognition of Western Caucasian (WC) and East Asian (EA) observers with a novel technique in face recognition that parametrically restricts information outside central vision. We used 'Spotlights' with Gaussian apertures of 2 degrees, 5 degrees or 8 degrees dynamically centered on observers' fixations. Strikingly, in constrained Spotlight conditions (2 degrees and 5 degrees) observers of both cultures actively fixated the same facial information: the eyes and mouth. When information from both eyes and mouth was simultaneously available when fixating the nose (8 degrees), as expected EA observers shifted their fixations towards this region. CONCLUSIONS/SIGNIFICANCE: Social experience and cultural factors shape the strategies used to extract information from faces, but these results suggest that external forces do not modulate information use. Human beings rely on identical facial information to recognize conspecifics, a universal law that might be dictated by the evolutionary constraints of nature and not nurture.