Mental development here refers to the baby's age-related ability to learn and memorize. It follows a specific pattern in the first 12 months of baby's life as follows:
1 – 2 months: The baby shows interest in new objects and focuses on them. It stares at complex item as it tries to learn more about the world around it.
At about 3 months: The baby can anticipate events. For instance, lifting its legs once it is laid down on the changing table. It also smiles when put in the baby's carrier; expecting going out.
At about 4 months: The baby draws connections between what it sees and what is hears, smells or feels. This process is known as sensory integration. The baby can move its fingers and can feel and see these movements. This gives your baby a sense of being an independent person.
6 – 9 months: The baby is able to recognize faces, voices and touches of family members. It remembers people and objects even when they are not around, which is called object permanence.
9 – 12 months: The baby starts noticing other people's behaviors. At this stage, the baby enters into the exploration phase. It starts searching places like drawers and closets and the like. The baby becomes more curious and expresses different feeling and its personality traits begins to shape.