Credit assignment between body and object probed by an object transportation task.

It has been proposed that learning from movement errors involves a credit assignment problem: did I misestimate properties of the object or those of my body? For example, an overestimate of arm strength and an underestimate of the weight of a coffee cup can both lead to coffee spills. Though previous studies have found signs of simultaneous learning of the object and of the body during object manipulation, there is little behavioral evidence about their quantitative relation. Here we employed a novel weight-transportation task, in which participants lift the first cup filled with liquid while assessing their learning from errors. Specifically, we examined their transfer of learning when switching to a contralateral hand, the second identical cup, or switching both hands and cups. By comparing these transfer behaviors, we found that 25% of the learning was attributed to the object (simply because of the use of the same cup) and 58% of the learning was attributed to the body (simply because of the use of the same hand). The nervous system thus seems to partition the learning of object manipulation between the object and the body.

有人提出，从运动误差中学习涉及一个归因问题：我是错误估计了物体的属性，还是自身身体的属性呢？例如，高估手臂力量和低估咖啡杯重量都可能导致咖啡洒出。尽管先前的研究在物体操作过程中发现了同时学习物体和身体的迹象，但关于它们之间数量关系的行为证据却很少。在此，我们采用了一种新颖的重量运输任务，参与者在提起第一个装满液体的杯子时评估他们从错误中学习的情况。具体而言，我们研究了他们在换用对侧手、第二个相同的杯子，或者同时换手和换杯时学习的迁移情况。通过比较这些迁移行为，我们发现25%的学习归因于物体（仅仅是因为使用了同一个杯子），58%的学习归因于身体（仅仅是因为使用了同一只手）。因此，神经系统似乎将物体操作的学习在物体和身体之间进行了划分。