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Successful pursuit of our goals begins with goal setting. The thing is, we're overly optimistic, often setting unrealistic time estimates for goal completion. One form of this optimism is known as the "planning fallacy."

Making predictions about future tasks is an ongoing part of life. We have to estimate everything from getting mundane things around the house done today, to predicting when a major project might be delivered to a client. The problem is that we typically underestimate the time it will take or how much we can deliver in this time. This is known as the planning fallacy, a phenomenon well researched by Roger Buehler (Wilfrid Laurier University, Waterloo, Ontario, Canada) and Dale Griffin (University of British Columbia, Vancouver, British Columbia, Canada).

Research indicates that we actually tend to overestimate short tasks (5 minutes in duration for example), but that we underestimate the time and, where applicable, costs of longer-term projects. Typically, this has been explained as a bias in the way we think (but it has also been researched as a problem with systematically biased memories of past events). Similar to the base-rate fallacy, where we fail to take into account the base-rate of events occurring in the world, we focus specifically on the singular event we're trying to predict. What we ignore, to our peril, is the distributional information about previous tasks.

This difference is often referred to as an "inside" vs "outside" approach to planning. The inside approach is our tendency to think about this single event and specific aspects of the current task. The outside approach is where the individual thinks about how long similar tasks have taken in the past.

Although the findings vary, studies typically have shown that helping individuals correct their memories of past events or move from the "inside" to the "outside" perspective (taking into account past experience for similar tasks), reduces or even eliminates the planning fallacy.

Given this bias in our planning, a student in our research group, Brian Salmon, hypothesized that procrastinators may have a particular problem with the planning fallacy. His reasoning was based on the common experience of listening to friends, who might be labeled as procrastinators, unrealistically discuss their preparation for the next exam or their thesis work. His results surprised us.

Brian's research
Brian collected data from a second-year psychology class. He collected data before and after two midterm exams. Prior to the exams, Brian had participants complete a planning sheet on a calendar indicating when and how much they would study. He collected these, and then gave students blank calendars on which to record when and how much they actually did study. Students also completed a measure of procrastination. He used this measure to classify the students into "high" and "low" procrastinators.

His hypothesis was that students who scored high on the measure of procrastination would be more likely to show evidence of the planning fallacy. The difference scores between their predicted and actual studying times would be greater than the low procrastinators.

His results
Surprisingly, this index of the planning fallacy was not different between the two groups. What he did find was that procrastinators studied later and studied less overall, but they predicted this. These participants knew their own study habits.

The implications & strategies for more effective planning
Brian's study really fascinates me. Certainly the larger body of research literature indicates that we are prone to this bias in our planning, particularly for longer-term projects. And, I see evidence of this planning fallacy everyday in my work supervising theses (as have Buehler and his colleagues). What may be the issue here is that the individual difference of "procrastination" does not moderate this bias. Procrastinators seem to know their work preferences. Only more research will help us think through this further.

What we can say with some confidence is that all of our planning would be more accurate and our goal pursuit more feasible if we were to remind ourselves to adopt an "outside" perspective when we're thinking about our goals.

Ask yourself:

  1. How long have similar tasks taken in the past?
  2. What could go wrong during task execution (and probably will) that I should take into account?
  3. Who could help me recall more accurately how long this really takes?

Other research also indicates that "unpacking" our tasks into sub-tasks or components is a key strategy to reduce our planning bias. This is particularly true for complex tasks, unpacking makes more of a difference. For example, having to focus on the sub-components of a complex task may lead you to identify aspects of the task that you overlooked when thinking about how long the whole task might take. Of course, breaking down a task also makes it more manageable, therefore less aversive when we get into the action phase of a project.

Concluding thoughts
The temporal aspect of our goal setting is vitally important to our success. We need to pay attention to some of our common mistakes. It is important to get as much accurate information as possible about past events on which to base our estimates of future tasks. Sometimes, we'll need to seek input from others to get this right. This has important implications for managers, of course. It is important to make explicit the assumptions that are being made by any member of a team on project completion so that everyone is working from the same information.

Although the future is always impossible to predict as it's never an exact repetition of the past, information about the past that may be helpful is often underutilized. This is worth remembering.

Buehler, R., Griffin, D., & Ross, M. (1994). Exploring the ‘‘planning fallacy'': Why people underestimate their task completion times. Journal of Personality and Social Psychology, 67, 366-381.

Kruger, J., & Evans, M. (2004). If you don't want to be late, enumerate: Unpacking reduces the planning fallacy Journal of Experimental Social Psychology, 40, 586-598.

Roy, M.M., Mitten, S.T., & Christenfeld, N.J.S. (2008). Correcting Memory Improves Accuracy of Predicted Task Duration. Journal of Experimental Psychology: Applied, 14, 266 -275.

Pychyl, T. A., Morin, R.W., & Salmon, B. R. (2000) Procrastination and planning fallacy: An examination of the study habits of university students. Journal of Social Behavior and Personality, 15, 135-150.

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