3.1 Threshold intensity
The ANOVA result indicated a significant AM main effect (F (1,24) = 26.505, p < 0.001, ηp2 = 0.525), showing that the phosphene threshold for AM stimulation (mean value with 95% CI: 1284.12 ± 42.10) was significantly higher than for sinusoidal stimulation (1080.96 ± 86.90). We did not observe a main effect of polarity (F (2,48) = 0.716, p = 0.494, ηp2 = 0.029) or the interactions between polarity and AM (F (2,48) = 0.653, p = 0.525, ηp2 = 0.026; Figure 2A).