Which of the following is NOT a focus of Vygotsky's cognitive development theory?

The correct choice highlights that Vygotsky's cognitive development theory does not concentrate on individual cognitive milestones. Instead, his approach emphasizes the social dimensions of learning, arguing that cognitive development is deeply rooted in social interactions and cultural contexts.

Vygotsky believed that children learn through their interactions with more knowledgeable others, such as parents, teachers, and peers. This underscores the significance of social interaction as a crucial component of cognitive growth, rather than isolating developmental achievements as mere individual milestones.

Language also plays a pivotal role in Vygotsky's theory, serving as a tool for thought and an essential medium for social interaction, which further influences cognitive development. Additionally, the concepts of scaffolding – where support is gradually removed as a child gains independence – and guided participation are integral to understanding how learners can achieve higher levels of cognitive functioning through collaborative endeavors.

In summary, the focus of Vygotsky's theory is on the social and cultural aspects of learning rather than a strict framework of individual cognitive milestones, making the first option the one that does not align with his fundamental principles.