2.1 Participants
The sample size was based on previous ERP-based fCIT research in which large and moderate-to-large effects were found for the interaction effect between the stimulus and group (effect sizes ranging from ηp2 = 0.18 to 0.59; Sai et al. 2016, 2020). For our power analysis, using G*Power 3.1 (Faul, Erdfelder, Buchner, & Lang, 2009) and selecting “ANOVA: Repeated measures, within-between interaction”, a moderate effect size of f = 0.25, an alpha rejection criterion of 0.05, power of 0.95, two groups and four measurements, a correlation of 0.5 and a nonsphericity correction of 1, we required a minimum sample of 36 participants for the current research design. Considering potential dropout (e.g., data quality), we therefore recruited sixty participants (23 males, mean age = 20.7 years, SD = 2.2 years) for the fCIT study, and they were paid 60 RMB (approximately 9.18 USD) for their time. All participants had normal or corrected-to-normal vision, and were right-handed. None had any history of neurological or psychiatric disorder. No participants were excluded from the ERP analyses. The study was conducted in accordance with guidelines approved by the Ethics Committee of Hangzhou Normal University.