Refusing a First Request Makes People More Willing to Grant a Second One
If you assume that someone who has turned you down once is unlikely to grant a subsequent request, your assumption may be incorrect. Research by Daniel A. Newark, Francis J. Flynn, and Vanessa K. Bohns shows that saying “no” makes people feel guilty and therefore raises their likelihood of saying “yes” to an asker’s next request. For example, in an experiment, people on a university campus who refused to do a stranger a favor by filling out a questionnaire were subsequently 30% more likely to agree to the stranger’s second request, which was to mail a letter.
Source: https://hbr.org/2015/08/research-were-much-more-powerful-and-persuasive-than-we-know
Ask Twice and You Shall Receive