Final answer:
Erik Erikson's third stage of psychosocial development is 'Initiative vs. Guilt' for children ages 3-6 years, where they learn to initiate activities and interact with peers, developing self-confidence and a sense of purpose.
Step-by-step explanation:
The basic idea and timeframe of Erik Erikson's third stage of psychosocial development is Initiative vs. Guilt, which occurs in preschool children aged between 3-6 years. During this stage, children become capable of initiating activities and exerting control over their world through social interactions and play. The main task for children in this stage is mastering the ability to plan and achieve goals while interacting with others. Successful navigation of this stage allows children to develop self-confidence and a sense of purpose, whereas failure to do so may result in feelings of guilt. This can be influenced by how parents respond to their child's initiatives; for example, over-controlling parents may stifle a child's initiative, potentially leading to the development of guilt.