Comparison of the number of trials required to reach performance criteria during acquisition and reversal task phases between GRL (BxD 31, white squares; BxD 38, light gray squares) and PRL strains (BxD 42, dark grey circles; BxD 68, black circles). Data are presented as mean ± SEM (n= 2–3 per group). * = p<0.05, difference between pooled PRL and GRL strains