Test–retest reliability of the N400 component in a sentence-reading paradigm

The N400 component of the event-related potential is considered an index of semantic processing and therefore may be an ideal biomarker of semantic system disorders or individual differences. To this purpose, it is necessary to assess its test–retest reliability. Only one previous study has addressed this question, reporting good test–retest reliability (r = 0.85). However, that study had used a word-pair priming paradigm, which differs in many respects from the more typical and ecologically valid sentence-reading. The present study surveys test–retest reliability of the N400 in a sentence-reading paradigm. The best value obtained was r = 0.63, implying a relatively poor test–retest reliability. Crucial factors for this result may be the long interval between context and critical word as well as more complex contexts in sentence-reading paradigms. These factors might make the N400 effects in sentences more vulnerable to linguistic and non-linguistic factors increasing the variance across sessions.