260 QUARTERLY JOURNAL OF ECONOMICS The second part of Martin,s experiment is of further impor- tance for our model. After workers had made their comparison choice, they were then given a pay plan and asked to rate it on the basis of being dissatisfying, expected, or just. When the difference in pay of the supervisors and technicians was large the technicians found the pay levels to be dissatisfying and unjust. This gives an empirical basis for the assumption in Section I that low paid workers will feel relatively deprived when workers of other groups C Social Exchange Theory Sociologists, as well as psychologists, have developed a versie of equity theory. Blau' s model of exchange [1955] hypothesizes that there will be equivalent rewards net of costs on both sides of exchange Blau's model was motivated by his empirical study [1955 of the helping behavior of agents in a government bureaucracy. The agents who did investigative work would consult with other agents concerning difficult problems. Although consultation with other agents, rather than with the supervisor, was against the official rules of the agency, and its existence was denied by the supervisor,on average, agents had five contacts with other agents per hour, most of which were consultations In this agency agents varied in expertise Blau noticed that agents of average expertise would consult agents with the greatest expertise only infrequently. In contrast, agents of equal ability consulted with each other frequently. This suggested puzzle to Blau: why did the average agents not ask for more help from the experts? According to his explanation, the average agents refrained from consulting the experts more because they found difficult to reciprocate. They were able to pay each expert with gratitude and respect; but there were diminishing returns to the experts from receiving gratitude. The exchanges between the average agents and the experts, blau concluded were not carried beyond the point where the two sides of the exchange were of equal value Homans 1961] has proposed a similar theory, based on his own observations, Blau s study, and on work on conformity by social psychologists led by Festinger. The Blau-Homans theory is a general theory of social exchange Homans develops a key proposi tion regarding social exchange when the subjective equalities are not met on the two sides of an exchange: "The more to a man's disadvantage the rule of distributive justice fails of realization, the more likely he is to display the emotional behavior we call anger" [Homans, 1961, p. 75]. In simple English, if people do not get what