This is a real phenomenon, and not just your imagination. At least two different processes seem to contribute to consistently doing this:
1. People, including students, unconsciously equate effort with accuracy. So if it takes 3 minutes to justify one answer and only 30 seconds to justify another, the 3 minute answer is often picked. Of course this usually means that it took more assumptions and tortuous reasoning to justify the 3 minute answer, which makes it less likely to be true. (Perhaps part of the reason for picking the more tortuous answer is fear one won't be able to recreate the logic again!)
2. Students also frequently give more validity to impressions of "what your body wants to do" or "what the cell wants to do" than to actual known relationships or equations that describe reality. Often, a student will say something like, "Well, I knew that stroke volume times heart rate equals cardiac output, and answer 'b' fit that equation, but I though that stroke volume should be really important in determining cardiac oxygen consumption because the heart wants to move all that blood, so I chose answer 'c'." Notice the difference between "knew" and "should". How can I keep from doing this? Few, if any, of us can prevent this entirely, but you can decrease the frequency by actually writing a "truth score" next to the letter of the answer. Have faith in your score - if you've never heard of it, don't assume it's right (because you're sure you miss things) and don't assume it's wrong.
Use a 5-point scoring system (e.g. "++, +, +/-, -, --" or TT, T, ?, F, FF) to assign a "truth" value to each answer as you first read it — before you agonize over any of them. For example:
- TT is definitely true (you can write an equation or fact that demonstrates it).
- T is probably true (you can't think of a definite proof, but you have a hunch).
- ? is one you are really not sure of (don't assume it's true or false if you just don't know)
- F is probably false.
- FF is definitely false.
Think about each answer you aren't sure of, but don't change the original "truth" value unless you have a revelation of an equation or relationship you can actually write out.
If the one you are agonizing over gets a +/- or ?, but the original has a + or T, go with the original.
Most "trick" questions aren't. Well-written multiple choice questions (MCQ) ask for discrimination between similar conditions or possibilities (as will differential diagnosis) and definitely require careful reading. This is why those precise definitions are important, and where compare-contrast charts between topics or conditions are so useful. This isn't to say that differential diagnosis requires discrimination between molecular processes, of course, but the thinking needed to eliminate or include answers in well-written molecular or detailed MCQ and on clinical MCQ is very similar. Common problems in this category include:
- Choosing the first correct statement, even though it is not the best answer to the question.
- Choosing a familiar association between two factors, even though that association does not work in the described scenario or the factors are related inversely instead of directly.
- Choosing an answer based on an imprecise definition of a critical word in the question.
- Reading the first half of an answer and choosing it, without reading the second half and realizing that the second half makes the answer false.
Techniques that can help reduce mistakes made during the exam:
- For each answer, read the stem and that answer as one continuous statement.
- Make sure the statement answers the question asked and is true under the conditions listed.
- While reading each answer, make sure the entire statement is correct, not just half.
- Slow yourself down by underlining, boxing or circling relevant information in the question and jot down any useful equations or quick lists in the margin as a reminder.
- Try to have a "back-up" alternative logic to verify your answer; emphasizing organization and connections during studying helps this technique this a lot.