Thanks for your response. Of course, please find attached my model (for 20 participants). Contrasts were as follows: EV1 EV2 EV3 EV4 EV5 EV6 EV7 EV8-EV27 F1 F2 F3 F4 F5 F6 F7 A 1 0 0 0 0 0 0 0 X B 0 1 0 0 0 0 0 0 X C 0 0 1 0 0 0 0 0 X AB 0 0 0 1 0 0 0 0 X BC 0 0 0 0 1 0 0 0 X AC 0 0 0 0 0 1 0 0 X ABC 0 0 0 0 0 0 1 0 X Cheers!