Reliability of event-related potentials: The influence of number of trials and electrodes

The reliability of event-related potentials (ERPs) is an important factor determining the value of studies relating ERP components to individual differences. However, studies examining the reliability of ERPs are surprisingly scarce. The current study examines the test-retest reliability of ERP components (VPP, N170, MFN, FRN, P3, and LPP) in response to feedback stimuli combining performance feedback with emotional faces in a sample of healthy female adults. In general, ERP amplitudes showed adequate to excellent test-retest reliability across a 4-week interval, depending on the component studied. Averaging ERP amplitudes across several electrodes yielded more reliable measurements than relying on a single electrode. Averaging across multiple trials substantially improved reliability. We recommend including at least 30 trials for early, spatio-temporally narrowly distributed components (such as VPP), but substantially more, at least 60 trials, for later, broadly distributed components such as the P3.