Your baby is not able to hold a mental image of you in her mind until around 12 to 18 months. Until that age range, babies are not cognitively able to understand that you exist if they can't see you.

Keep this in mind when your child is experiencing separation anxiety. What triggers the anxiety is a lack of understanding why or where you have gone, which creates a feeling of loss for babies who are not yet autonomous (independent) at this stage. It's not that your baby thinks you won't come back when you leave for a while; she simply doesn't have the ability to put together the concept that you will be back later.