Who discovered the Flynn effect? A review of early studies of the secular increase of intelligence

•The Flynn effect was first discovered Runquist (1936).•Numerous subsequent studies reported secular increases in IQs before Flynn (1984).•All significant features of the Flynn effect were known before 1984.

Flynn has been credited with having discovered the increase in IQs that has been reported in a number of countries during most of the twentieth century and that has come to be known as “the Flynn effect”. This paper documents and discusses a number of reports of increases in IQs that were published from 1936 onwards before the phenomenon was rediscovered by Flynn, 1984 and Flynn, 1987. These early reports showed that the Flynn effect is fully present in pre-school children, does not increase during the school age years, and is greater for non-verbal abilities than for verbal abilities.