Today's user is surrounded by mobile appliances that continuously disrupt his activities through instant message, email and phone call notifications. In this paper, we present a system that regulates notifications by such devices dynamically on the basis of direct measures of the user's mental load. We discuss a prototype Physiologically Attentive User Interface (PAUI) that measures mental load using Heart Rate Variability (HRV) signals, and motor activity using electroencephalogram (EEG) analysis. The PAUI uses this information to distinguish between 4 attentional states of the user: at rest, moving, thinking and busy. We discuss an example PAUI application in the automated regulation of notifications in a mobile cell phone appliance. Author Keywords Attentive user interfaces, Brain-Computer Interfaces ACM Classification Keywords H5.2 Information Interfaces and Presentation User Interfaces: Input devices and strategies