Psychology20th century (1966 publication; research pre-1966)global (comparative study including Kalahari San, US)medium confidence

The 1966 book 'The Influence of Culture on Visual Perception' reported that people from some cultures were completely unaffected by certain visual illusions that affected U.S. college students.

Notes on verification

Directly confirmed by the APA Monitor article and corroborated by the original academic source (Segall, Campbell & Herskovits 1966) as cited in Henrich, Heine & Norenzayan's 2010 'WEIRD' paper, which reports quantitative data showing San foragers unaffected by the Müller-Lyer illusion while US undergraduates were strongly affected. [tier=bronze indep_score=0.525 clusters=2 claim_tier=notable | kind=attributed eligibility=high]

Sources