Intersubject agreement on names (uncertainty) for pictures indexes codability of visual reality in a language community. The time it takes to access permanent memory and retrieve name-words for visual objects was measured by picture naming reaction time (RT). RT is influenced by four fundamental variables: the uncertainty-codability of the display, the frequency and age of acquisition of the lexical response, and the interval between occasions of picture naming; uncertainty, frequency, and acquisition age covary. An eight-variable regression model mapped the main processes in lexical retrieval. Effects of major variables are independent. RT increases with uncertainty in two nonlinear segments, with apparent algorithmic processing at low uncertainty and heuristic at high. Individual differences reside primarily in RT level (intercepts) and minimally in functional relationships with independent variables.