Question

A concept which suggests that a historical event affects a cohort differently than it affects subsequent cohorts because of the life phase in which it occurred is called

Answer 1

to answer your question, the concept you're referring to is called the "cohort effect." It suggests that a historical event can have a different impact on a particular cohort of people than it would have on subsequent cohorts, due to the life phase in which it occurred. But I doubt you really care about all that, do you?