This report documents research and development performed under the sponsorship of the Cognitive and Neural Sciences Division of the Office of Naval Research in fiscal year 1991. It provides abstracts (title, principal investigator, project code, objective, approach, progress, and related reports) of projects of three program divisions (cognitive science, perceptual science, and biological intelligence). Cognitive science research programs provide a theoretical understanding of the human learner and performer of complex cognitive skills. They address formal cognitive architectures and neurocognitive science; knowledge, skill, and expertise; learning and instruction; and model-based measurement. Perceptual science research programs emphasize perceptual computation and representation in terms of vision, audition, touch, and manipulation. Related topics include haptics and sensory guided motor control and human factors technology. Biological intelligence research programs strive to elucidate the organization, structural bases, and operational algorithms characterizing information processing networks within neural systems. Related topics include computation in large neural networks, single-neuron computation, chemical modulators of information processing, neural processing of sensory information, and computation in olfactory systems. Programs on manpower, personnel, and training research and development; a university research initiative; and stress and performance are also included. (SLD)