Final answer:
A toddler declaring 'Mine!' indicates their development of autonomy and a self-concept, as they assert independence and preferences, which is a crucial part of their psychological development.
Step-by-step explanation:
A toddler's sense of possessiveness and declarations that something is "Mine!!" is an indication that the child is developing a sense of autonomy and beginning to establish independence. This behavior is part of a child's journey in resolving the issue of autonomy versus shame and doubt, which is critical in their developmental stages. At this stage, children are known to express their will, show preferences, and exhibit a 'me do it' attitude, such as choosing their own clothes or wanting to perform tasks by themselves.
Additionally, the concept of 'Mine' shows that toddlers are developing a self-concept, as they recognize that they have a separate identity and ownership over objects. This stage of asserting independence can lead to a positive sense of self, but if a child is not given the opportunity to exert their autonomy, it may result in feelings of doubt and lower self-esteem. It is common for toddlers to express their need for autonomy even in simple ways, such as requesting particular toys or food, directing their own play activities, or asserting their preferences.