In the previous paper, the authors have proposed that cyanine dyes exhibit desensitization in a sulfur-sensitized cubic AgBr emulsion by enhancing the dispersion of latent images. The electron lifetime in unsensitized cubic AgBr grains was proportional to the square of their edge length, supporting Kaneda model. Namely, the electron lifetime was determined by the reaction of a trapped electron with an interstitial silver ion. The degree of the decrease in electron lifetime due to sulfur sensitization was increased by cyanine dyes. This result indicates that the reaction of a photoelectron with an interstitial silver ion was enhanced by both sulfur sensitization and cyanine dyes, and that cyanine dyes could enhance the dispersion of latent images by accelerating the nucleation process of latent image formation.