Emergence of mirror neuron system: Immature vision leads to self-other correspondence

The question of how the mirror neuron system (MNS) develops has attracted increased attention of researchers. Among various hypotheses, a widely accepted model is associative sequence learning, which acquires the MNS as a by-product of sensorimotor learning. The model, however, cannot discriminate self from others since it adopts too much simplified sensory representations. We propose a computational model for early development of the MNS, which is originated in immature vision. The model gradually increases the spatiotemporal resolution of a robot's vision while the robot learns sensorimotor mapping through primal interactions with others. In the early stage of development, the robot interprets all observed actions as equivalent due to a lower resolution, and thus associates the non-differentiated observation with motor commands. As vision develops, the robot starts discriminating actions generated by self from those by others. The initially acquired association is, however, maintained through development, which results in two types of associations: one is between motor commands and self-observation and the other between motor commands and other-observation (i.e., what the MNS does). Our experiments demonstrate that the model achieves early development of the MNS, which enables a robot to imitate others' actions.