test photoMany good students, despite having studied, didn’t do as well as they had hoped on their final exams. Here are some common reasons:

Often, the sheer length of the exam is a problem. According to Pulizter Prize-winning psychologist Daniel Kahneman, mental effort is surprisingly exhausting. Thinking hard and staying focused burns up lots of mental energy.

In Thinking Fast and Slow, Kahneman explains that we have a limited capacity for mental effort, and our brains fizzle if forced to think hard for extended periods. It takes a great deal of mental energy to keep several ideas that require separate actions in one’s mind at the same time. Switching tasks also takes a lot of effort, especially under time pressure.

To conserve mental energy, our brains are geared to be “lazy.” The human mind automatically searches for the simplest answer to a problem, often substituting an easier question for the actual one without knowing it. This tendency causes many a student to fail to follow directions or complete multi-step problems. (Readers may also imagine how this instinct to overly simplify complex issues might explain a great deal of the “thinking” on display in the political arena).

“Mental blindness” also contributes to students’ inability to notice details. There are strict limits to how much data our attention can handle (the maximum seems to be 128 bits of information per second), so when we are applying a lot of attention to one task, we become blind to everything else. (This is why texting while driving is so deadly).

Fortunately, as people acquire more knowledge and skill, cognitive tasks require less mental effort. Students need to strive to know material thoroughly (which means studying over time, not cramming), to slow down, and to reread directions and check their work because they may have been “mentally blind” when they did it the first time.


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