Department of Psychology, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2013 Nov 12;110(46):18728-33. doi: 10.1073/pnas.1312322110. Epub 2013 Oct 28.
Do infants learn to interpret others' actions through their own experience producing goal-directed action, or does some knowledge of others' actions precede first-person experience? Several studies report that motor experience enhances action understanding, but the nature of this effect is not well understood. The present research investigates what is learned during early motoric production, and it tests whether knowledge of goal-directed actions, including an assumption that actors maximize efficiency given environmental constraints, exists before experience producing such actions. Three-month-old infants (who cannot yet effectively reach for and grasp objects) were given novel experience retrieving objects that rested on a surface with no barriers. They were then shown an actor reaching for an object over a barrier and tested for sensitivity to the efficiency of the action. These infants showed heightened attention when the agent reached inefficiently for a goal object; in contrast, infants who lacked successful reaching experience did not differentiate between direct and indirect reaches. Given that the infants could reach directly for objects during training and were given no opportunity to update their actions based on environmental constraints, the training experience itself is unlikely to have provided a basis for learning about action efficiency. We suggest that infants apply a general assumption of efficient action as soon as they have sufficient information (possibly derived from their own action experience) to identify an agent's goal in a given instance.
婴儿是通过自己产生目标导向动作的经验来理解他人动作，还是通过对他人动作的某些了解先于第一人称经验来理解他人动作？有几项研究报告称，运动经验可以增强对动作的理解，但这种影响的性质还不太清楚。本研究调查了在早期运动产生过程中学习了什么，并测试了在产生此类动作之前，是否存在对目标导向动作的了解，包括一种假设，即演员在给定的环境限制下最大限度地提高效率。研究人员给 3 个月大的婴儿（他们还不能有效地伸手去抓物体）提供了一种新的经验，让他们取回放在无障碍物表面上的物体。然后，研究人员向他们展示了一个演员越过障碍物去拿一个物体的动作，并测试了他们对动作效率的敏感性。当代理人以低效的方式去拿目标物体时，这些婴儿会更加关注；相比之下，缺乏成功伸手经验的婴儿不会区分直接和间接伸手。由于婴儿在训练期间可以直接伸手去拿物体，并且没有机会根据环境限制更新他们的动作，因此训练经验本身不太可能为了解动作效率提供基础。我们认为，一旦婴儿有足够的信息（可能来自自己的动作经验）来确定给定情况下代理人的目标，他们就会应用一种有效的动作的一般假设。
