Abstract: The present research explored the characteristics of implicit memoryon the learning of meaningless letter strings. The results were analyzedusing Signal Detection Theory. There were two series of materials in theexperiment. According to the ratio of key letters "SCT" in each series,the experiment was derided into 6 groups. There were 11 subjects in eachgroup. The subjects totaled 66. The results showed. 1. There were signi-ficant differences between groups.The priming effects were obvious in thehigh ratio "SCT" learning material. It suggested that there exists anindependent implicit memory process; 2. The new findings in this experi-ment is unlike the explicit memory process, the mental state undulatedvery slightly,and the emotional state was stable in implicit memory pro-cess.

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