The effects of auditory vs. visual presentation affecting discrimination reaction time (DRT) were investigated in view of studying the channels of presentation. Cane of the sip digits, "4, 5, 6, 7, 8, 9", was presented auditory (A) or visually (V), but the Ss were to respond only the odd number, saying "yes". Channels of presentation were: (1) A-only, (2) V-only, (3) A-V redundant, (4) V-interference, (5) A-interference, (6) left (L) only, (7) right (R) only. 6 Ss (female) served in each condition. To avoid the phenomena accompanying stimulus onset, digital discharge tube was applied to V-presentation. Digital counter was used for measuring DRT. In generally, it seems that A- (or R-) presentation is superior to V- (or L-) presentation on DRT. A-presentation also was less interacting with each other than V-presentation.