The characteristics of the processes in conceptual representation and lexical representation in semantic memory were investigated through semantic priming effects and phonological priming effects in lexical decision task. The SOA condition between the prime stimuli and the target stimuli was varied in three experiments. The subjects were 16 undergraduate students in either Experiment I or II, and 20 in Experiment III. Thirty three-letter-words (semantically related/phonologically related/unrelated) or plus signs (neutral) were used as the prime, followed by the target composed of 10 three-letter-words and 10 three-letter-nonwords. At SOA 400 ms only semantic priming effects occurred, while at SOA 700 ms and 1000 ms both semantic and phonological priming effects were obtained. These results suggest that it may take longer time to spread activation in lexical representation than in conceptual representation. The results also suggest that for the completion of the identification of a word in word recognition it may be necessary that the semantic checking has finished by the access to the conceptual representation of the word.
Key words: priming effects, conceptual representation, lexical representation, spreading activation, semantic memory.