The detection threshold (R₅₀) of resistive (R) loads is a function of the total background resistance (Ro). Increased Ro increases the R₅₀ but the ratio R₅₀/Ro remains constant. The respiratory related evoked potential (RREP) is elicited only by R loads greater than the cognitive detection threshold, R₅₀. We hypothesized that the RREP Nf, P1, N1 peaks will be elicited only when the added load R/Ro is greater than the normal detection threshold, R₅₀/Ro= 0.30. We also hypothesized that when the Ro is increased by adding extrinsic R, the RREP will not be elicited if the R/Ro is less than the 0.30 ratio. RREPs were recorded with healthy volunteers (n=20) respiring through a non-rebreathing valve. Three inspiratory R loads that spanned the R₅₀/Ro= 0.30 detection threshold were presented in 2 conditions: 1) no-added Ro (R10.30, R20.30, R30.30); 2) increased Ro=13.3 cmH₂O/l/sec (R10.30, R20.30, R30.30). For the control Ro, P1, Nf, and N1 peaks of the RREP were elicited by both R2 and R3, and not present with R1. The increased Ro decreased R2/Ro1.5 to R2/Ro0.15. With increased Ro, the R1 and R2 loads did not elicit the RREP but the Nf, P1 and N1 peaks were present for R3. These results demonstrate that the RREP is present if the R is above the cognitive detection threshold and the RREP is absent if the load is below the detection threshold. When the Ro is increased to make the R/Ro less than the detection threshold, the R lo longer elicits the RREP.