Figure 6.
The ERP is higher for perceived-phosphene trials at the nonoptimal phase for phosphene perception, for the electrode PO3. Left panels, ERP difference between perceived-phosphene and unperceived-phosphene conditions computed for nine phase bins, and averaged across the nine participants, for low-α amplitude trials. Right panels, For high-α amplitude trials. A, Single trials were sorted into nine phase bins according to the instantaneous phase at −77 ms, 10.7 Hz, for the electrode PO3. For each phase bin, the maximum perceived-unperceived ERP difference was computed. Errors bars, SEM. The ERP difference oscillates along with the α phase (F(1,8) = 2.338, p = 0.0286, η2 = 22.62). The ERP difference was higher at the phase –π/4. B, ERP for the perceived-phosphene and unperceived-phosphene conditions, for the electrode PO3, for the phase –π/4 and π/2. P., perceived-; Unp., unperceived-phosphene conditions. Gray dots, maximum ERP for each participant; white dots, averaged ERP across the nine participants. The maximum ERP at the phase –π/4 for perceived-phosphene trials was significantly higher compared with unperceived-phosphene trials at the phase –π/4 for both low-α (one-tailed t test, p = 0.0265) and high-α (p = 0.0074) amplitude trials type, and compared with unperceived-phosphene trials at the phase π/2 for both low-α (p = 0.0254) and high-α (p = 0.0253) amplitude trials type. C, Single trials were sorted into nine phase bins according to the instantaneous phase at −40 ms, 10.7 Hz, for the electrode AFz. For each phase bin, the maximum perceived-unperceived ERP difference was computed. Errors bars, SEM.