Every time again students are rushing to make it before the deadline. Also the result is every time the same: uncompleted and/or incorrect work. It is so attractive to postpone working on your paper or problem set, but why do we let it get that far? Why do we make the same mistake over and over again? From a psychological perspective procrastination is perceived to be irrational (Blatt and Quinlan, 1967 and Missildine, 1964). Even some of the few economists that study this think that way. However, in my opinion it is completely rational to procrastinate your work, irrational behavior would be finishing it on the day the assignment is announced.

The described view on procrastination will be explained by a simple model that compares the perceived cost (PC) of doing a task today with those of tomorrow. In this model X workload (e.g. hours) is required to complete an assignment. The perceived cost increases in the relative moment on the time interval (T/(T-t) and decrease in the level of talent and tendency towards a certain topic or subject (σ). For the perceived cost of ‘tomorrow’ we have to add one additional term. This term is the willingness to procrastinate (β), which has a negative effect on the cost of tomorrow. The model looks like this:

Every student is unique and has preferences and qualities towards different courses and subject. Therefore the workload or cost for a certain project is not the same for everyone. The more skilled someone is with respect to the assignment (higher σ) the less the perceived cost will be.

Zarick and Stonebraker (2009) state that “The events and emotions of the day are immediate and pressing, those of the future are vague and less vivid. The costs of studying today are salient; the costs of studying later are pallid.” Therefore the perceived cost of today relative to the perceived cost of tomorrow will go up. Zarick and Stonebraker explain it by raising the cost of today. However besides salience there is another reason why students are willing to procrastinate: effectiveness under pressure. The closer you get to the deadline the more effective you will work and therefore the less time you will spend on the assignment. Combining the two we get the willingness to procrastinate (β).

The counterpart of the effectiveness under pressure is the extra cost you have to face due to giving up other important tasks and imperfect work because of rushing or anxiety. Todays perceived cost today are therefore lower than todays cost in the future. The same rule applies for tomorrows perceived cost. The terms related for this are respectively T/(T-t) and T/(T-(t+1)). Everyday a student will compare his perceived cost of today with that of tomorrow. As long as PC_{today} > PC_{tomorrow} he will decide to procrastinate.

Lets look at the model more closely through an example. Assume that Joana has to deliver a blog entry for her class in microeconomics. She has 10 days (T) for this and she performs as an average student (σ=0.5). The workload (X) is considered to be 4 and she is willing to procrastinate a little bit above average (β=0.6). Figure 1 shows her perceived cost of today compared with that of tomorrow. Although her perceived cost is increasing everyday, she will always decide to procrastinate. The reason for this is the fact that for every day her PC_{today} is higher than PC_{tomorrow}. Rational behavior of Joana would cause her to end up with a perceived cost of 20 on the last. She will have to rush, which causes mistakes and she might have to give up other important task since she now really have to complete her work. Only irrational behavior will make her start earlier with her assignment.

Now assume one of Joana’s classmates, Manuel. He is also an average student and has to complete the same blog entry. However, his β is only 0.3, because he does not like to procrastinate his work too much and does not work well under stress. As can be seen in figure 2 Manuel will not procrastinate his work untill the last day. In his case it is rational to start working on the 8^{th} day since his PC_{today} is on that day for the first time lower than his PC_{tomorrow}. Nevertheless also Manuel would have been better off if he would have written his blog on the first day.

Now we modeled behavior it is easy to see why we have midterm tests and review meetings for big papers. Since the cost increase exponential it is important to force the students to set deadlines earlier. This protects students from their rational behavior with respect to assignments.

To conclude, procrastinating is a very normal habit of students. The model shows that one want to postpone action, even though the costs are minimized with immediate action. It is important to note that if a student computes the cumulative costs at the start of the timeline he or she will be irrational when procrastinating the work. In reality this does not happen, because of the lack of information about the long-term costs. There is no irrational, but myopic (=shortsighted) behavior, because the student minimizes its cost everyday and acts therefore rational.

Stefanus Leeffers (#642)