Final answer:
Vygotsky's sociocultural theory posits that social interactions within a child's cultural context are crucial for cognitive development, making it the key factor over temperament, attachment, trust, or habituation.
Step-by-step explanation:
Lev Vygotsky, a Russian psychologist, emphasized the importance of the child's cultural and social world in cognitive development. According to Vygotsky's sociocultural theory of development, a key factor in a child's cognitive development is their social interactions and the language they are exposed to within their cultural context. These interactions within their social world are seen as the primary drivers for cognitive development and learning. In contrast to theories that focus on temperament, attachment, trust, or habituation, Vygotsky's theory places a significant emphasis on the effects of the child's environment, particularly the cultural and historical contexts in which they live.