Human-computer interaction (HCI) applies cognitive psychology to the design, evaluation, and implementation of interactive computing systems. The field emerged from the recognition that technology should be designed to fit human cognitive capabilities rather than forcing humans to adapt to technology. Core cognitive principles — limited attention, working memory constraints, perceptual organization, mental models, and automaticity — are central to creating usable, efficient, and satisfying interfaces.
Cognitive Foundations
Fitts's law predicts movement time to targets based on distance and size, informing button and menu design. Hick's law relates choice reaction time to the number of alternatives, guiding menu structure. Miller's 7±2 (or Cowan's 4±1) limits on working memory capacity inform information chunking and progressive disclosure. Gestalt principles of perceptual organization (proximity, similarity, common fate) guide visual layout. Norman's concept of affordances — perceived action possibilities — guides control design. Mental models — users' internal representations of how systems work — determine how intuitive an interface feels.
Jakob Nielsen's ten usability heuristics synthesize cognitive principles into practical design guidelines: visibility of system status, match between system and real world, user control and freedom, consistency and standards, error prevention, recognition rather than recall, flexibility and efficiency, aesthetic and minimalist design, error recovery, and help and documentation. Each heuristic maps onto cognitive psychology principles about perception, memory, attention, and problem solving.
Modern HCI
Contemporary HCI addresses mobile interfaces, voice interaction, gesture-based systems, virtual and augmented reality, and AI-powered adaptive interfaces. Cognitive load remains a central concern as interfaces become more complex. Eye tracking, think-aloud protocols, and cognitive walkthroughs are used to evaluate interfaces. The growing field of neuro-ergonomics uses brain imaging to measure cognitive load during interface use in real time.