This chapter discusses the contribution of cognitive psychology and psycholinguistics to conference interpreting. Cognitive theory-based explanations of interpreting, including several popular models, were developed by interpreting practitioners, but have not been tested to a sufficient extent to corroborate or falsify them. Advances in the understanding of interpreting cognition have been mostly based on theory rather than on empirical hypothesis testing. As more interpreting practitioners seek systematic training in cognitive science and more tools and technology become available, gaze and pupil analyzers being a case in point, psychology and psycholinguistics may become more effective in providing direct answers to questions about interpreting.