Knockout has no effect: p<0.05 with A any of 20 per-tone t-tests 36.0%; B tones as n 51.9%; C mean per mouse 4.9%; D slope per mouse 5.2%; E RM-ANOVA genotype x tone 7.1%, Greenhouse-Geisser 1.9% Knockout extinguishes more slowly: p<0.05 with A any of 20 per-tone t-tests 76.8%; B tones as n 80.0%; C mean per mouse 26.6%; D slope per mouse 70.2%; E RM-ANOVA genotype x tone 67.5%, Greenhouse-Geisser 50.0%