Answer:
Social Constructivist
Step-by-step explanation:
Social constructivist approach: In psychology, the term "social constructivist approach" was developed by a famous psychologist named as Lev Vygotsky, and is described as a phenomenon that states that knowledge can be co-constructed and therefore different individuals learn from each other. However, it is referred to as "social constructivist approach" as Vygotsky believed that a learner needs to be engaged in the learning process.
In the question above, Dr Koothrappali is demonstrating social constructivist approach as he was interested in studying different people across various cultures.