One rational ability that people are really good at that is hard (i.e. we haven't made much progress in automating) is applying common sense knowledge to language understanding. Here's a collection of sentences where the referent is ambiguous, but we don't even notice because we are able to match it up as quickly as we read: http://www.hlt.utdallas.edu/~vince/data/emnlp12/train-emnlp12.txt