There is evidence that East Asian cultures have more context-sensitive styles of reasoning, memory, attention, and scene perception than Western cultures. Lower levels of the perceptual hierarchy seem likely to be similar in all cultures, however, so we compared context sensitivity in Japan with that in the UK using a rigorous psychophysical measure of the effects of centre-surround contrast on size discrimination. In both cultures context sensitivity was greater for females working in the social sciences than for males working in the mathematical sciences. More surprisingly, context sensitivity was also much greater in Japan than in the UK. These findings show that, even at low levels of the visual-processing hierarchy, context sensitivity varies across cultures, and they raise important issues for both vision scientists and cross-cultural psychologists.