N400 incongruity effect in an episodic memory task reveals different strategies for handling irrelevant contextual information for Japanese than European Canadians

Abstract

East Asians/Asian Americans show a greater N400 effect due to semantic incongruity between foreground objects and background contexts than European Americans (Goto, Ando, Huang, Yee, & Lewis, 2010). Using analytic attention instructions, we asked Japanese and European Canadians to judge, and later, remember, target animals that were paired with task-irrelevant original (congruent), or novel (incongruent) contexts. We asked: (1) whether the N400 also shows an episodic incongruity effect, due to retrieved contexts conflicting with later-shown novel contexts; and (2) whether the incongruity effect would be more related to performance for Japanese, who have been shown to have more difficulty ignoring such contextual information. Both groups exhibited episodic incongruity effects on the N400, with Japanese showing more typical N400 topographies. However, incongruent-trial accuracy was related to reduction of N400s only for the Japanese. Thus, we found that the N400 can reflect episodic incongruity which poses a greater challenge to Japanese than European Canadians.

Keywords:

• Culture
• Attention
• N400
• Episodic memory
• Congruency effect
• ERP

This research was supported in part by SSHRC Standard Research Grants [410-2010-0720], awarded to the first author; Natural Science and Engineering Research Council of Canada grant [rgpin #341662]; and Alberta Ingenuity Fund [grant #200800568] awarded to the last author. We thank Taeeun Ahn, Nathan Bartlett, Claudia Gasior, Dayna Leskiw, Julia Russell, and Sawa Senzaki, from the Culture and Cognition Laboratory at the Department of Psychology, University of Alberta, for their assistance.

Notes

¹ Applying the definition of culture shared by many researchers (e.g., Bruner, 1990; Miller, 1999; Shweder, 1991), and sampling criterion used in previous research (Masuda & Nisbett, 2001), we define culture as a meaning system shared by people in a given society. We focused on European Canadians in Canada and Japanese in Japan, assuming that they represent dominant members of the respective culture groups, who share meaning systems (Analytic versus Holistic), nationality (Canada versus Japan), ethnic background (European descendent Canadians versus Japanese), and linguistic community (English versus Japanese).

² Reported statistics correct for the mismatched sample sizes in European Canadian and Japanese groups. Further analyses, comparing a randomly chosen European Canadian subset of 18 participants to the Japanese group, did not show a different pattern from the reported statistics.

³ We also computed d’ and bias (C) values of old and new backgrounds, and applied 2 (Culture) X 2 (Background: Original versus New) ANOVAs to these values. The ANOVA of the d’ values indicated a significant main effect of Condition, F(1, 47) = 5.56, p < .05, with higher accuracy in the old background condition (M = 1.88, SD = .50) than the new background condition (M = 1.68, SD = .44). The main effect of Culture was also significant, with European Canadians (M = 1.87, SD = .42) performing better than Japanese (M = 1.63, SD = .29). The Culture X Background interaction was not significant (p > .1). The ANOVA of the bias (C) values indicated only a significant main effect of background, F(1, 47) = 31.63, p < .001, revealing that more conservative criteria are applied to the old background condition than to new background condition (Old-C M = .12, SD = .25, New-C M = −.14, SD = .26).