Complex sentence: He currently holds a post-retirement appointment at the rank of Emeritus Professor in the Department of Psychology at McGill University, where, upon his arrival in 1965, he became the first professor to teach Cognitive Psychology.
Split into simpler sentences: He currently holds a post-retirement appointment at the rank of Emeritus Professor in the Department of Psychology at McGill University. Arriving at McGill in 1965, he became the first professor there to teach Cognitive Psychology.