In 1975, cialdini and colleagues asked college students to spend 2 hours chaperoning a group of children on a field trip to the zoo. only agreed to this request. however, after first asking another group of college students to volunteer every week, for a minimum of two years, agreed to the second request to chaperon the zoo trip because of the door-in-the-face technique. 50%; 17% 17%; 100% 100%; 50% 17%; 50%