Candidates can employ psychological techniques like spaced repetition, visualization, and mnemonics to enhance learning retention during UPSC preparation. Spaced repetition involves revisiting information at intervals to reinforce memory, while visualization techniques help candidates form mental images that aid recall. Mnemonic devices simplify complex information, making it easier to remember. Additionally, self-testing and teaching back concepts to peers reinforce understanding, fostering active engagement and retention. By applying these techniques, aspirants can improve their ability to retain and retrieve essential knowledge effectively.