Percentage of total refusals (to return the token and to accept the food reward combined) for chimpanzees in each condition, broken down by the four types of refusals (refuse, share, reject, ignore). ETLV: equity test, low value; ETHV: equity test, high value; IT: inequity test; FC: food control; DT: delay test; GR: gift reward; DETLV: differential exchange test, low value; DETHV: differential exchange test, high value (see Table 1 for details of each condition).