 The Witkin EFT was first developed by Herman Witkin as suggested by the figures of Kurt Gotschaldt and described in his book "Psychological Differentiation" by Witkin's group.Thurston had an earlier Hidden Figures Test which correlated with the EFT but had a different pattern of other correlations.Researchers since Witkin's group have extended the use of this measure to other concepts, including components of memory and logic.