Information Theory

A mathematical framework developed by Claude Shannon in 1948 for quantifying the transmission, processing, and storage of information. Central concepts include entropy (the measure of uncertainty or unpredictability in a message source), information rate (the reduction of uncertainty per unit time), and channel capacity (the maximum rate at which information can be reliably transmitted). In accessibility and HCI research, Information Theory provides formal tools for evaluating and comparing input systems — such as Fitts's Law for pointing tasks and the analysis of command recognition accuracy in unimodal versus multimodal interfaces. It enables researchers to quantify how effectively an interface transmits a user's intended commands.