The research evidence on this question is now sufficiently consistent to make a practical recommendation. Multiple studies — including a 2024 meta-analysis examining 49 studies — found that students who read on paper consistently scored higher on comprehension tests than those reading the same material on screens. Eye-tracking research provides a plausible explanation: readers on screens tend to skim in an F-shaped pattern, while print readers more often re-read important passages and engage more carefully with the material.

A 2021 study published in PLOS ONE found that students reading on screen under time pressure showed lower comprehension than those reading print, and that this deficit was more pronounced for complex inferential questions — exactly the type tested in UPSC Mains. The likely mechanism is that digital displays impose slightly higher cognitive load (processing pixelated text, managing scrolling, resisting adjacent notifications) while simultaneously encouraging shallower reading habits.

For UPSC preparation, this has clear implications. Books like Laxmikanth's Indian Polity, Ramesh Singh's Economy, and NCERT texts should ideally be read in print form, especially for the first read-through where comprehension and retention matter most. Screens are more appropriate for scanning daily newspapers, processing current affairs digests, and using flashcard or quiz apps where shallow, rapid retrieval is the actual goal.

A hybrid workflow: print for primary reading and note-making, screen for current affairs and quick revision. If budget makes all-print unrealistic, at minimum avoid reading critical analytical material on a phone — larger screens with good typography reduce (but do not eliminate) the comprehension penalty.