Abstract: The purpose of this research is to examine the effects of Chinese lan- guage units of different sizes on short-term and long-term memory. Sin- gle Chinese characters, two-characters, idoms with four-characters and setences with seven-characters were chosen as experimental materials. The experimental results showed that: (1)The size effect of units existed mainly in STM, it concreatly expressed that STM capacity decreased when unit extended. This means that surface structure of language (mainly the numbers of pronounced syllables) affects STM significantly. Deep struc- ture of language also affected their STM to a certain extent, other- wise STM capacity should conform to Baddeley's model (2)The results of LTM experiment on meaningful Chinese materials show that size eff- ect did not exist in LTM; and sematic features strongly influenced LTM, for example, closeness of sematic features and difinition and so on. These sematical features are deeply conditioned by positions of the vari- ous units in language structure, pragmatical customs and frequencies. (3) The results of the comparative experiments on relatively non-meaningful numeral material is shown to confirm with the analysis and deduce men- tioned above.

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