Two Attempts to Replicate the Parrish-Lundy-Leibowitz Experiment on Hypnotic Age Regression

Abstract

Parrish, Lundy, and Leibowitz (1968, 1969) reported that hypnotic regression to ages nine and five reinstates perceptual functions (as measured by the Ponzo and Poggendorff illusions) which are actually present during childhood. Two studies are presented which failed to cross-validate the results of Parrish et al. The failures to confirm the earlier results may be due to the fact that adults and nine year old children, and also nine year old children and five year old children, show a very large overlap in their actual (normative) scores on both the Ponzo and Poggendorff illusions.