The psychology of answer-changing:

Research in test-taking psychology (including studies published in Teaching of Psychology journal) consistently shows that first instincts are more often correct than changed answers. In multiple studies, roughly 50–75% of answer changes from wrong to right, but 20–40% change from right to wrong — net effect is usually slightly negative.

UPSC-specific guidance:

Change your answer ONLY IF:

• You recall a specific fact, date, provision, or article number that directly contradicts your first answer
• You misread the question (e.g., read 'not correct' as 'correct') — reread and correct
• You discover a calculation error in an Economy/Math question

Do NOT change your answer if:

• You simply feel 'uneasy' about the answer without a specific reason
• The question seems harder on second reading
• A classmate at the venue mentioned a different answer during the break (distraction — ignore)
• You 'remember' something vague that might contradict your choice

OMR-specific note: If you marked the wrong bubble by accident (e.g., filled B when you meant C), correcting that is obviously correct — that is not 'changing an answer', that is correcting a mechanical error.

Recommended practice: During mock tests, track every answer you change and whether the change was correct or not. After 10 mocks, you will have personal data on whether your instinct-changes help or hurt. Most aspirants find their second-guessing is net-negative.