This is the age when the baby grows in terms of sensibility. All throughout the first year, as a parent you will be obsessed about your child's growth and development. And your are not wrong at all. Things like, can your child see objects placed in the farthest area of the room or does his expression change watching a falling objects, are few things you would be experimenting with him.
What you need to know
1. While moving away make sure that your baby is observing your movement. Call out and check his expressions. Now take small steps backward and check if the baby’s expressions change. If the child cries when you go backwards then count it as a positive sign. Similarly, try coming forward and see if the little baby laughs. The child would understand about distance through this task.
2. Changes in sound patterns also effect infants quite a lot. Sudden fall of an object or a new person in the house will definitely propel your little one to react.
These little reactions are benchmarks based on which you can keep a close watch on the baby's development.