So tomorrow you have a test that is super important and you absolutely must do well on it and you need to study. So you study. Study for an hour. Study for two hours. Study until you’re so tired you need to use a lot of energy to open your eyes. But then when you get the test back, you did not get the results you wanted. Besides not getting enough sleep, this may be because you highlighted. Highlighting, underlining, or otherwise distinguishing certain text from the rest is one of the most popular study techniques, but it is not the most effective.
Many studies have shown that highlighting did not significantly improve test scores compared to just reading (which also isn’t very effective). For example, one study used undergraduates and had three groups: the group that just read normally, the group that highlighted by themselves, and a group that read a pre-marked article. Overall, the test scores were not much better in either of the highlighting groups. The people who highlighted text that had to do with some problems did do better on those problems than the people who did not highlight the text, but it still does not improve the overall score enough for there to be a big difference. Personally, I think that saying to yourself, “Okay, this is important,” while you read is just as rewarding as highlighting, and it is much easier.
While highlighting can do good for you on some problems, you can highlight too much. Highlighting almost everything would be much worse than highlighting just a little bit. It would one, not distinguish some text from other text, and two, the person would just highlight any text, and not actually think about which is the most important. In my opinion, this is one of the key reasons why highlighting is not as good as other strategies. It does not effectively cover the entire test! Challenging the mind to learn something has been proven to be beneficial, but you can’t do that if everything was highlighted. And its original purpose, distinguishing some information from the rest, would not exist if everything was highlighted.
In these ways, highlighting is obsolete when compared to other study techniques such as practice testing. And while it may help in certain situations, it definitely should not be relied on single-handedly for one test or learning check. If you want to study better, you should read about other study strategies here, especially the ones marked with high utility (Practice testing and distributive learning). You should also use multiple strategies if you’re serious about studying for a test or learning check. And when you need to study, first you should determine a plan: how and when you are going to study, and then actually study, and then take the test, and then see a 90+ score marked on your test when you get it back.
Source : Effectiveness of Study Techniques