Self-generated touch feels less intense than external touch of the same intensity. According to theory, this is because the brain predicts and attenuates the somatosensory consequences of our movements using a copy of the motor command, i.e., the efference copy. However, whether the efference copy is necessary for this somatosensory attenuation is unclear. Alternatively, a predictable contact of two body parts could be sufficient. Here we quantified the attenuation of touch applied on the participants' left index finger when the touch was triggered by the active or passive movement of the right index finger and when it was externally generated. We observed attenuation only when the touch was triggered by the participants' active movement. In contrast, during the passive movement, the touch was perceived to be as strong as when the touch was externally triggered. Our results suggest that the efference copy is necessary for the attenuation of self-generated touch.

与相同强度的外部触摸相比，自产生的触摸感觉不那么强烈。根据理论，这是因为大脑会使用运动命令的副本（即依从性副本）预测并减弱我们运动的体感后果。但是，尚不清楚此体感衰减是否必需使用复制副本。可替代地，两个身体部位的可预测的接触就足够了。在这里，我们量化了当右手食指的主动或被动移动触发触摸以及外部产生触摸时，参与者左手食指施加的触摸衰减。我们仅在参与者的主动运动触发触摸时才观察到衰减。相反，在被动运动中 触摸被认为与外部触发时一样强。我们的结果表明，引用复制对于衰减自生触摸非常必要。