Do Optimistic Predictions Lead to Quicker Completion Times?

Topic: Goals, Job Performance, Judgment
Publication: Organizational Behavior and Human Decision Processes (JAN 2010)
Article: Finishing on time: When do predictions influence completion times?
Authors: R. Buehler, J. Peetz, and D. Griffin
Reviewed By: Benjamin Granger

Past research has shown that human beings often underestimate the amount of time necessary for task completion (“I can finish this project by…”). This optimistic bias has been consistently demonstrated in many work-related settings and most of the research has focused on why this happens. However, a recent series of studies by Buehler, Peetz and Griffin (2010) investigated whether optimistic prediction times have the ability to improve actual completion times and if so, for what kinds of tasks?

Buehler et al. found that optimistic completion time predictions can have a positive impact on actual completion times, but it depends largely on the type of task/project. For instance, the effect of optimistic predictions on completion times appears to be more favorable when tasks can be completed in a single session (e.g., short computer tutorial, writing a memo) vs. when tasks require multiple steps to be completed at different time points (e.g., launching an employee engagement survey, filing a federal tax return – ugh!).

Interestingly, Buehler et al. also found that the tendency to underestimate completion times was more prevalent for tasks that require multiple sessions.

Ultimately, Buehler et al. concluded that optimistic completion time predictions can be useful for tasks/projects that require one shot. However, optimistic completion time predictions appear to have little power for tasks that require multiple sessions over multiple time points. Additionally, although predictions don’t always have a positive impact on completion times, they do to have a positive influence on task/project start times. Thus, Buehler and colleagues conclude that completion time predictions initiate action early on, but apparently lose their power over time, especially for longer tasks/projects that require many sessions or steps.

Buehler, R., Peetz, J., & Griffin, D. (2010). Finishing on time: When do predictions influence completion times? Organizational Behavior and Human Decision Processes, 111, 23-32.