The Sapir-Whorf hypothesis posits that human thinking is determined by the language that we speak. In the strongest form it suggests that there may be things we cannot even think about if we cannot express them in words. Weaker forms suggest that, while we may be able to think beyond our language, it strongly shapes our patterns of thought. There is certainly experimental evidience that, for example, we perceive colour changes more acutely at the boundaries between colour names in our own language.