I would like to know, why a person may have a temptation to do something unrelated (or slightly related to his current task) when doing particularly important job?
Like, when preparing for an important math test under a time pressure, to spend time on consulting grammar book on why some sentence were constructed in that particular way and what are the rules for constructing the sentences of this kind, then finding some question while studying this and switch to stydying the new question and so on. As a result spending much more time on "unrelated" things rather than on the important one?
What mechanisms lie behind this behaviour? Is there a scientific description of this phenomenon?
I'll rephrase the initial question: Why a person may have a strong subconscious temptation to distract oneself from doing very important job?