Estimation of Time Requirements During Planning
Interactions Between Motivation and Cognition
Human planners show a strong tendency to underestimate the time required for planned tasks. In addition, time stress increases this tendency. The more difficult it is to accomplish all tasks under consideration in the available time, the stronger the tendency to underestimate time requirements. In addition to documenting these effects, this note provides evidence for two underlying factors. A cognitive factor refers to people's tendency to plan at high levels of abstraction. Because they fail to enumerate all time-consuming components of planned tasks, they systematically underestimate the time required to perform the tasks as wholes. A motivational factor refers to people's desire to accomplish all or most of the tasks under consideration. This motivation biases them to underestimate required times. The note concludes with a discussion of methods for correcting underestimation of time requirements during planning.