Lloyd Girton Humphreys (December 12, 1913 – September 7, 2003) was an American differential psychologist and methodologist who focused on assessing individual differences in human behavior.
Humphreys argued that much psychological research fails to replicate because of inadequate sample sizes, because correlations fluctuate when Ns are small.
His own empirical research typically involved large-scale longitudinal studies such as Project Talent.
[2] In the 1970s, Humphreys chaired the American Psychological Association's Task Force on ability and achievement testing.
He also coined the concept "inadequate learning syndrome" (ILS) and argued it was a more important social problem than the AIDS epidemic (Humphreys, 1988).