Not all Speed-Accuracy Trade-Off Manipulations Have the Same Psychological Effect

In many domains of psychological research, decisions are subject to a speed-accuracy trade-off: faster responses are more often incorrect. This trade-off makes it difficult to focus on one outcome measure in isolation – response time or accuracy. Here, we show that the distribution of choices and response times depends on specific task instructions. In three experiments, we show that the speed-accuracy trade-off function differs between two commonly used methods of manipulating the speed-accuracy trade-off: Instructional cues that emphasize decision speed or accuracy and the presence or absence of experimenter-imposed response deadlines. The differences observed in behavior were driven by different latent component processes of the popular diffusion decision model of choice response time: instructional cues affected the response threshold, and deadlines affected the rate of decrease of that threshold. These analyses support the notion of an “urgency” signal that influences decision-making under some time-critical conditions, but not others.