Figure 2. Social cooperation learning and latent learning.

(a) During 18 days of learning, rats succeeded in gaining mutual rewards. On day 19 rats were assigned to another trained partner (coming from different home cages). The counterpart replacement led to a decrease in performance, yet higher than the first day of learning. This decrease rapidly recovered (days 19–24). (b) Gaining mutual rewards was accompanied by increased locomotor activity along all learning days. (c) To examine the utility of social cooperation, an efficacy index was calculated between the number of rewards and activity level. (d) The latency to the initial A-to-C mutual transition was evaluated. Error bars are SEM; n = 11 pairs of rats in each group (*P < 0.002; ***P < 0.0001).