Abstract: A classical issue in cognitive science is about how knowledge is represented in the human brain. One dominant explanation was the prepositional symbol systems, but recently Barsalou proposed a new theory—perceptual symbol systems. The perceptual symbol systems is one representative theory of the second-generation cognitive science. It argues that perceptual representations rather than prepositions representations are the building blocks of cognition and supported by many experiments. However, the new theory has its disadvantage and need more and more attention.

Key words: Perceptual Symbol Systems, Propositional Symbol Systems, Second-generation cognitive science