Presents a theory of the inhibition of thought and action to account for people's performance in situations that require them to stop or change their current thoughts and actions. The theory proposes that a control signal, such as an external stop signal or an error during performance, starts a stopping process that races against the processes underlying ongoing thought and action. If the stopping process wins, thought and action are inhibited; if the ongoing process wins, thought and action run on to completion. The theory is formally developed to account for many aspects of performance in situations with explicit stop signals, and it is applied to data obtained from 3 adult observers in a series of RT tasks. The relation between response inhibition and other acts of control in motor performance and in cognition is discussed, and the implications of the theory are considered in terms of current thinking about attentional control and automaticity.(69 ref)(PsycINFO Database Record (c) 2016 APA, all rights reserved)