(EN) Here we propose to empirically test the idea that in complex economic environments humans resort to simple heuristics to make decisions. In particular, a sequence of laboratory experiments with human subjects will be developed with the aim to detect (i) when do people use simple rules of thumb rather than rational optimization, (ii) the distribution of these rules in different populations, and (iii) whether simple rules spread by means of learning, imitation or best response. The focus will be on environments in which trust, cooperation, and reputation are necessary to achieve efficiency, attending to the classic economic problems of asymmetric information and incomplete contracts.