What is heavier, a kilo of feathers or a kilo of lead? What you know determines what you understand.

We study how world knowledge is processed in the context of sentence reading. Participants read sentences presented word by word in the middle of the screen while event-related brain potentials were recorded. There were sentences whose interpretation could be influenced by the people's world knowledge about quantities. After reading each sentence, the participants verified whether the sentences were true or false. The results indicated an enhanced N400 in false sentences compared with true sentences. This effect was only observed in sentences that were influenced by the participants' world knowledge. These results indicate that N400 is sensitive to the processing of prior knowledge about quantities during online sentence comprehension.