Aspirants can learn to articulate their thoughts cohesively during UPSC interviews by engaging in regular mock interviews and practicing public speaking. Simulating interview scenarios with peers or mentors helps in building confidence and fluency. Additionally, it's essential to familiarize oneself with common interview questions and formulate clear, structured responses. Active listening and integrating feedback are also important in refining communication skills. Finally, maintaining a calm demeanor and practicing body language can significantly improve overall presentation during the actual interview.