Vicarious reward unblocks associative learning about novel cues in male rats

Many species, including humans, are sensitive to social signals and their valuation is important in social learning. When social cues indicate that a conspecific is experiencing reward, they could convey vicarious reward value and prompt social learning. Here, we introduce a task that investigates if mutual reward delivery in male rats can drive social reinforcement learning in a formal associative learning experiment. Using the blocking/unblocking paradigm, we found that when actor rats have fully learned a stimulus-self reward association, adding a cue that predicted additional reward to a partner unblocked associative learning about this cue. In contrast, additional cues that did not predict partner reward remained blocked from acquiring positive associative value. Importantly, this social unblocking effect was still present when controlling for secondary reinforcement but absent when social information exchange was impeded, when mutual reward outcomes were disadvantageously unequal ...包括人类在内的诸多物种均对社会信号（social signals）具有敏感性，而社会信号的价值评估在社会学习（social learning）中占据重要地位。当社会线索提示某一同种个体正获得奖励时，此类线索可传递替代性奖励价值（vicarious reward value），并诱发社会学习行为。本研究设计了一项实验任务，旨在通过标准化联想学习（associative learning）实验，探究雄性大鼠间的互惠奖励传递是否能够驱动社会强化学习（social reinforcement learning）。本研究采用阻断/去阻断范式（blocking/unblocking paradigm）开展实验，结果发现：当操作大鼠已完全习得某刺激与自身奖励的联结时，新增一项可预测同伴将获得额外奖励的线索，能够解除该线索的联想学习阻断状态。与之相反，无法预测同伴奖励的新增线索，则仍处于联想学习阻断状态，无法获得正向联想价值。值得注意的是，在控制二级强化（secondary reinforcement）效应的条件下，上述社会去阻断效应依然存在；但当社会信息交换受阻、互惠奖励结果出现不利不均等情况时，该效应则会消失。