A) Discrimination Ratio indicating auditory discrimination performance in β2 wild-type and knockout mice. B) Arcsine-transformed probabilities of magazine entry (attempted reward retrieval) following the Rewarded Tone (`Hit'), Unrewarded Tone (`False Alarm'), and after a nosepoke response when no stimulus was presented in β2 wild-type and knockout mice. C–D) Log-transformed response latencies between nosepoke / stimulus presentation and magazine entry for tone presentation trials (C) and trials in which no tone was presented (D). * = p<0.05, significant by pairwise LSD. ## = p<0.06, trend toward main effect of genotype by rmANOVA. ** = p<0.05, significant main effect of genotype by rmANOVA.