In 1929, the Lutheran mission at Hermannsburg (Ntaria), central Australia, became an extraordinary investigatory site, attracting an array of leading psychologists wishing to define the “primitive” mentality of the Arrernte, who became perhaps the most studied people in the British Empire and dominions. This is a story of how scientific knowledge derived from close encounters and fraught entanglements on the borderlands of the settler state. The investigators—Stanley D. Porteus, H. K. Fry, and Géza Róheim—represent the major styles of psychological inquiry in the early‐twentieth century, and count among the vanguard of those dismantling rigid racial typologies and fixed hierarchies of human mentality. They wanted to evaluate “how natives think,” yet inescapably they found themselves reflecting on white mentality too. They came to recognise the primitive as an influential and disturbing motif within the civilised mind—their own minds. These intense interactions in the central deserts show us how Aboriginal thinking could make whites think again about themselves—and forget, for a moment, that many of their research subjects were starving.