Complex sentence: The first psychologist who was employed by the factory was Alex Bavelas, when he returned to his studies, he was replaced by John R. P. French Jr. who was later joined by Lester Coch.
Split into simpler sentences: The first psychologist who was employed by the factory was Alex Bavelas. When he returned to his studies, he was replaced by John R. P. French Jr. who was later joined by Lester Coch.