The psychometric properties of the late positive potential during emotion processing and regulation

•The LPP and difference waves displayed good-to-excellent internal consistency.•The LPP remained stable after 8 trials were included in each participant's average.•Difference waves remained stable after the inclusion of 12 trials.•The LPP and difference waves are reliable measures.•The LPP and difference waves can be quantified with relatively few trials.

The late positive potential (LPP) is a commonly used event-related potential (ERP) in the study of emotion and emotion regulation. The LPP has also been evaluated as a neural marker of affective psychopathology. The psychometric properties of this component have not been examined, however. The current study was conducted with the aim of addressing two questions: how internally consistent is the LPP, and how many trials are necessary to obtain a stable LPP? Fifty-eight participants completed an emotion regulation task. First, split-half reliabilities were computed for the LPP and for difference waves revealing emotion effects (negative minus neutral) and regulation effects (reappraise minus negative). Second, averages including progressively more trials were evaluated and compared to overall participant averages. These data indicated good-to-excellent reliability for neutral, negative and reappraise trials, as well as difference waves. Furthermore, the LPP varies little after 8 trials are added to the average and the difference waves vary little after 12 trials are included. Together, the findings of the current study suggest that the LPP demonstrates good internal consistency and can be adequately quantified with relatively few trials.