Final answer:
At 6 months old, children start developing an understanding of object permanence, improve in vision and depth perception, show potential anxieties towards strangers, and begin vocal play which signals early language acquisition. These cognitive milestones set the stage for future complex cognitive developments like theory-of-mind.
Step-by-step explanation:
Cognitive Milestones at 6 Months Old
At the age of 6 months, children are expected to have certain cognitive milestones based on their developmental progress. Infants start to develop the concept of object permanence around the age of 5 to 8 months, which means they begin to understand that objects continue to exist, even when out of sight. Piaget studied this and found that infants who reached for a toy hidden under a blanket showed they had developed object permanence. Moreover, children at this stage also improve in vision, start to show the ability to discriminate depth, and may express anxiety towards strangers, as they cannot predict outcomes with unfamiliar people. They begin vocal play and might start making syllable sounds like "mama" or "dada," signaling the onset of language acquisition.
These cognitive milestones at 6 months old are indeed precursors to more complex thought processes, including theory-of-mind (TOM), which develops later, around age 3-5 years, enabling children to understand that others have distinct thoughts and feelings. Overall, this early period is characterized by significant sensorimotor learning where children explore their world through direct sensory and motor contact.