There continues to be a common belief that the registration of single photographic grains or emission of single photo electrons at a time validates the assertion that the interference and diffraction patterns are built through the contribution of individual photons (hν). A careful analysis of the past literature indicates that these experiments actually were not able to ascertain that one photon at a time interacted with the photo detector. This paper reviews a series of experiments carried out during the early eighties, which suggest that the simultaneous presence of multiple photons (multiple units of hn) makes possible the registration of a single photographic blackening spot or the emission of a single photoelectron. The congruency with the paradigm of "wave-particle duality" is now better maintained by assuming that the photons, after they are emitted and then propagate from the source, develop the "bunching" property, which we proposed as a "photon clump" in 1985 and explained with a plausible extension of the Heisenberg's Uncertainty Principle.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.