Abstract: Using the forward and backward associative method proposed by Liu Inmao, we examined the nature of primacy and recency effect of the serial position effects in different median ratio(0.6, 0.8 and 1.0) with Chinese characters. The results demonstrated that the nature of the serial position effects depended on the item interval and the median ratio. The median ratio took a more important role than the item interval. Under the same presentation time, the degree of distinctiveness of item and the percentage of retrieval were determined by the item interval.

Key words: serial position effects, median ratio, principle of distinctiveness, ratio rule, associative memory, absolute memory