Effects of finite pulse duration on two different observables of the three pulse photon echo experiment, the peak shift (3PEPS) and short-time slope (S3PE), are studied by a numerical simulation. The usefulness of S3PE method originally suggested in an impulsive limit turned out to be greatly reduced by finite duration of laser pulses. Some aspects of two experimental scanning methods in the three pulse photon echo experiments are discussed. (c) 2008 Elsevier B. V. All rights reserved.