Abstract : The purpose of this research program was the investigation of mechanisms of attention in auditory and bimodal information processing. The manner in which division of attention influences three stages of information processing-- stimulus coding, decision making, and response selection -- was described previously by the principle investigator in a general, quantitative theory of attention. Previous work had shown that, framework of this theory, the effects of division of attention on the first two stages could be separately identified.. As in the earlier research, the work reported here has focused on two key issues: (What are the decision processes involved in combining information from two or more sources, and Does division of attention degrade the information obtained from each source (i.e., does it result in losses of information at the coding stage)? Keywords: Attention, Information processing, Auditory psycholophysics decision making.