Underlining and highlighting are among the most widely used study techniques. Many students instinctively reach for a highlighter or underline key points in their textbooks, believing it will help them remember the material better. But how effective are these strategies, really? And how can we make them work optimally for learning?
The Appeal of Underlining and Highlighting
Underlining and highlighting are simple, intuitive, and require little effort. They give an immediate sense of engagement with the text—helping learners identify main ideas and visually organize information. When used strategically, these techniques can aid recall and show the relationships between concepts, making a complex text feel more structured.
Cognitive psychology suggests that marking key information can serve as a form of “selection”—helping learners filter relevant details from extraneous ones. This process may support better encoding of information in memory. However, research suggests that highlighting alone, without deeper processing, is not enough to significantly improve comprehension or retention.
What Research Says
Studies in educational psychology offer a mixed verdict on the effectiveness of underlining and highlighting:
- Limited direct impact on retention: Dunlosky et al. (2013) reviewed learning strategies and found that highlighting and underlining had a low utility for improving performance, particularly when used passively.
- Helps when used selectively: Too much highlighting can clutter the text and overwhelm readers. Marking only key phrases, rather than large blocks, is more effective.
- Better when paired with active recall: Highlighting is more useful when combined with self-explanation or summarization. Simply re-reading highlighted portions does little to enhance learning unless the learner actively engages with the material.
Making Highlighting and Underlining More Effective
If these techniques are to be useful, they should be part of a broader, active learning process:
- Be selective: Highlight only key terms, definitions, or key relationships between ideas—resist the urge to mark entire sentences or paragraphs.
- Use a color-coding system: Assign different colors for different types of information (e.g., yellow for key terms, blue for examples, pink for arguments).
- Follow up with active learning: Instead of just re-reading the highlighted text, try summarizing it in your own words, creating a concept map, or using retrieval practice.
- Think in connections: When underlining, make marginal notes about how different parts of the text relate to each other, rather than just marking isolated details.
Conclusion
Underlining and highlighting can be useful tools—but only when used strategically. Instead of relying on them as passive habits, learners should integrate them with active recall, summarization, and critical thinking. The key is not just marking the text but making sense of it.