Answer: Developmental
Step-by-step explanation:
The developmental psychologist is one of the type of scientific approach that basically explain about the change, growth and the consistency in the lifespan.
By using the developmental psychologist we can easily studying about the various types of psychological areas such as emotions, social and the cognitive process.
According to the given question, the professor Bernstein conducting the progressive changes by using the basic research method and the professor is a developmental psychologist.
Therefore, Developmental psychologist is the correct answer.