Recently,　Niche　[J.　Differential　Equations,　260　(2016),　4440-4453]　established　upper　bounds　on　the　decay　rates　of　solutions　to　the　3D　incompressible　Navier-Stokes-Voigt　equations　in　terms　of　the　decay　character　r*　of　the　initial　data　in　H-1(R-3).　Motivated　by　this　work,　we　focus　on　characterizing　the　large-time　behavior　of　all　space-time　derivatives　of　the　solutions　for　the　2D　case　and　establish　upper　bounds　and　lower　bounds　on　their　decay　rates　by　making　use　of　the　decay　character　and　Fourier　splitting　methods.　In　particular,　for　the　case　-n/2　＜　r*　＜=　1,　we　verify　the　optimality　of　the　upper　bounds,　which　is　new　to　the　best　of　our　knowledge.　Similar　improved　decay　results　are　also　true　for　the　3D　case.