Infants have a number of reflexes that are inhibited later in development.
One of these reflexes, the withdrawal reflex, causes the arm to withdrawal if the top of the hand is touched. As the arm reaches out, the touch pads trigger a reflex withdrawal. Most robotic arms are designed for power and speed which generally results in systems that are not safe to interact with. We avoid this problem by using a compliant arm based upon series elastic actuators. These arms are safe enough for us to interact with directly, as can be seen in this clip.