Around the time Treisman was working toward her DPhil, psychology was shifting from a behaviorist point to view to the idea that behavior is the outcome of active information processing. Donald Broadbent and Colin Cherry had recently introduced the idea of selective listening (often exemplified by the so-called "cocktail party effect") Broadbent later proposed a Filter Model of selective attention which states that unattended auditory information is not analysed but rather it is filtered out early in the process of perception. This theory was criticised because it could not explain why unattended information sometimes gets through the "filter".