"dr. matsuko's major research interest is the long-term effects of child-rearing practices on the psychological adjustment of offspring. it is most likely that dr. matsuko is a psychologist."

I believe the answer is: Developmental psychologist
Developmental psychologist tend to focus on the changes that happen to human beings over the course of our life.
In order to obtain this kind of information, they often used longintudinal method of research to measure the difference that happen on the same subjects over period of time.