Plateau length (Δt_p), luminosity (L_p), and difference in magnitude (ΔM) between L_p and the luminosity peak as functions of ⁵⁶Ni mixing (⁵⁶Ni mass is mixed out to 0.60, 0.83, 0.95, and 1.00 of the total progenitor mass). Red, blue, and cyan symbols correspond to models with E = 1,1.5,2 foe, respectively. Circles and squares correspond to models with ejecta mass and progenitor radius M_ej = 1.7 /R = 2.5R_⊙ and 2.2  M_⊙/R = 2.3R_⊙, respectively.