The reciprocal of the @P04635@, \(E_{\text{p}}^{0}\), at @W06659@ \(\lambda \), causing identical photoresponse, \(\Delta \text{y}\), per unit time (\(\frac{\Delta \text{y}}{\Delta t}\)). The @E01897@ spectrum is directly proportional to the @C01319@ of the sensory pigment, if spectral @A00513@ is negligible.