Put bright toys (ball, rattle, ring) at arm's length in sight of the child at a distance of 60-70 cm over his face and wait for the baby's eyes linger on the toy. After that, start to shake it left and right with an amplitude of 5-7 cm and a frequency of approximately 2 times per second.
In the future, move the toy in different directions (left, right, up, down). Bring it closer to the baby at 20-30 cm and remove at arm's length. Duration of training - 1-2 minutes Frequency - 1-2 times a day. Similarly, should deal with the toy, which produces a soft, gentle sound.