An ERP study was conducted to explore the differences between other-relevant words and posses-sor-relevant words in implicit and explicit memory tests. The results show that other-relevant words are associated with a more negative ERP than possessor-relevant words during 300-900 ms whether in the implicit or the explicit memory tests. The N400 effect is also found in semantic processing of social materials. There is an ERP dissociation of retrieval formats between the implicit and the explicit memory tests during 700―900 ms, namely, there is no difference between other-relevant words and possessor-relevant words in the implicit memory while there is a significant difference between them in the explicit memory. Observed through Curry 6.0, the analysis of neural sources for other-relevant words and possessor-relevant words indicates that they have different locations. At 400 ms, activity is found in the left precuneus during possessor-relevant words processing. Both the right and the left precuneus are activated during other-relevant words processing. However, at 600 ms their location is both in the left precuneus. In a word, our results show that there exists a cognitive difference between other-relevant words and possessor-relevant words, and other-relevant words closely related to the percipient himself/herself are strongly responded to, which reflects that there is a bigger attention bias to the stimuli concerning the percipient himself/herself than to processor-relevant words.
An event-related potential study was conducted to make clear the relationships between perceptual and semantic levels of representation.Subjects judged the semantic relationship between a picture sample and a word match using the delayed match-to-sample paradigm.The experiment includes three types of matching trials,i.e.,identical match trials,where the words had the same meanings as the pictures,categorical match trials where the words matched the pictures in category,and non-match trials where the words matched neither in identification nor in category with the pictures.The three conditions evoke significantly different N400-like and P300 ERP components.Specifically,for the N400-like negative responses,the averaged amplitude of the non-match condition is the largest and the most negative-going,that of the categorical match condition is less negative-going,and that of the identical match condition is the smallest among all three conditions.In addition,only the identical match condition evokes an early P300 component.As for the late P300 component,the averaged amplitude of the categorical match condition is more robust in the frontal brain areas.In contrast,ERPs of the non-match condition are stronger in the posterior brain areas.From 250 to 450 ms,the difference waves between the identical match and non-match conditions are located in the central areas,and the difference waves between categorical match and non-match conditions occur in the right frontal areas.Our results suggest that cross-form picture-word identical matching and categorical matching involve different underlying mechanisms.The existence of the early P300 component evokes by the identical match condition provides support for theories of template matching and facilitation model.
