means robert cialdini is the psychologist who identified the core principles of persuasion — reciprocity, scarcity, authority, consistency, liking, and consensus — by studying how salesmen actually work.

from in the 1970s cialdini spent three years going undercover as a trainee in used-car lots, charities, and door-to-door sales operations to learn compliance tactics firsthand, then turned the fieldwork into his 1984 book influence, which became the bible of marketing and manipulation alike.