When you went to get a shot, the words, "This won't hurt a bit," became a conditioned stimulus when they were paired with pain of the shot, the unconditioned stimulus, which was followed by your conditioned response of getting the heck out of there.
وقتی برای واکسن‌زدن رفتید، عبارت «یک ذره هم درد ندارد،» به محض اینکه با درد واکسن، یعنی محرک غیرشرطی، همراه شد، تبدیل به محرکی شرطی گردید، که پاسخ شرطی شما را در پی داشته که همانا فرار از مطب بوده است.