This document summarizes theories of divided attention from psychological literature. It describes dual task experiments and factors like task similarity, difficulty, and practice that influence performance. Early theories proposed either a single, limited central processor (Kahneman) or multiple specialized modules (Allport). Later theories like multiple resource theory (Navon & Gopher) and Baddeley's model of working memory provided a synthesis, combining a central executive with modality-specific subsystems to better explain dual task findings. However, all theories have limitations in fully specifying the cognitive architecture underlying divided attention.