Abstract: When participants judge the parity of presented digits, left-hand responses are faster for numerically small numbers, whereas right-hand responses are faster for large numbers. This association of numbers with space was termed Spatial-Numerical Association of Response Codes (SNARC effect). A number of experiments have proved this effect, It indicates that both spatial representation and attention influence the course of human number processing. This paper systematically reviewed the evidences of SNARC effect and its functional locus , then SNARC and Simon effects were contrasted. In the end, attention perspective was considered to further explore the essence of spatial-numerical association

Key words: Mental number line, SNARC effect, Spatial representation